Warsaw University of Life Sciences

Annals Warsaw University of Life Sciences

Forestry and Wood Technology No 96 Warsaw 2016

Contents: KAMILA PŁOŃSKA, JAROSŁAW SZABAN, WOJCIECH KOWALKOWSKI, MARCIN JAKUBOWSKI “Dynamics of change in the cut-to-length timber market in Poland“ 7 MARZENA PÓŁKA, BOŻENA KUKFISZ “Analysis of explosive parameters of jatoba dust in wood and furniture industry” 12 KAZIMIERZ PRZYBYSZ, KAMILA PRZYBYSZ, BORUSZEWSKI PIOTR, “Application of cellulosic pulps from fast-growing plants in production of packaging papers” 17 KAMILA PRZYBYSZ, KAZIMIERZ PRZYBYSZ “Evaluation of dimensional properties of cellulosic fibers as a tool for swift, initial evaluation of papermaking potential of pulp” 25 RATAJCZAK IZABELA, KOWALEWSKI PAWEŁ, WOŹNIAK MAGDALENA, 1SZENTNER KINGA, NOWACZYK GRZEGORZ, MICHAŁ KRUEGER, COFTA GRZEGORZ “TiO2-SiO2 as a potential agent in wood preservation” 26

1 WOŹNIAK MAGDALENA, RATAJCZAK IZABELA, KINGA SZENTNER, IWONA RISSMANN, GRZEGORZ COFTA “Investigation of the use of impregnating formulation with propolis extract and organosilanes in wood protection – chemical analyses. Part I: FTIR and EA analyses” 32 RATAJCZAK IZABELA, WOŹNIAK MAGDALENA, MICHAŁ KRUEGER, SŁAWOMIR BORYSIAK “Investigation of the use of impregnating formulation with propolis extract and organosilanes in wood protection – chemical analyses. Part II: AAS, XRF and XRD analyses” 38 WOŹNIAK MAGDALENA, RATAJCZAK IZABELA, AGNIESZKA WAŚKIEWICZ, KINGA SZENTNER, GRZEGORZ COFTA, PATRYCJA KWAŚNIEWSKA-SIP “Investigation of the use of impregnating formulation with propolis extract and organosilanes in wood protection – biological analyses” 43 BARTŁOMIEJ RĘBKOWSKI, KRZYSZTOF J. KRAJEWSKI, AGNIESZKA MIELNIK “Comparison of susceptibility of European aspen (Populus tremula L.) and oak (Quercus sp.) against molds Aspergillus niger (Tiegh) and Chaetomium globosum ((Kunze)Fr.)” 48 ALENA ROHANOVÁ, PETER KRIŠŠÁK “Finger- joints in lamellas of beech wood (Fagus sylvatica L.)” 55 ALENA ROHANOVÁ, PETER KRIŠŠÁK “Poplar wood (Populus tremula L.) findings of finger - jointed timber” 60 VALERJAN ROMANOVSKI, PAWEŁ KOZAKIEWICZ, MARIUSZ MAMIŃSKI, ALBINA JEGOROWA “Клеевое соединение между основанием и древесиной как фактор стабилизирующий дубовые половые дощечки” 65 ANNA ROMANOWSKA, MARIUSZ MAMIŃSKI “The effect of long-time storage of PRF resin on its physical and chemical properties” 71 PAWEŁ ROSZKOWSKI, PAWEŁ SULIK “Fire resistance of timber floors – part 1: Design method” 77 PAWEŁ ROSZKOWSKI, PAWEŁ SULIK “Fire resistance of timber floors – part 2: Test method” 82 ANNA ROZANSKA, ANNA POLICINSKA-SERWA “Methods and possibilities for conservation of antique wooden floor in Poland – theory and practice” 87 DANIEL RUMAN, VLADIMÍR ZÁBORSKÝ, VLASTIMIL BORŮVKA, MILAN GAFF “Experimental testing of a spatial furniture joint” 96 BARTŁOMIEJ SĘDŁAK, DANIEL IZYDORCZYK, PAWEŁ SULIK “Aluminium glazed partitions with timber insulation inserts – fire resistance tests results depending on the type of used wood” 102 ANNA POLICINSKA-SERWA, ANNA ROZANSKA “Methods and possibilities for conservation of antique wooden floor in the light of current construction standards” 107

2 GABRIELA SLABEJOVÁ, MÁRIA ŠMIDRIAKOVÁ, JÁN PETRIĽÁK “Adhesion of foils to MDF board” 115 GABRIELA SLABEJOVÁ, MÁRIA ŠMIDRIAKOVÁ, ZUZANA GAJDOŠÍKOVÁ “Quality of finish on bonded layered material made from beech veneer and foamed PVC” 120 GABRIELA SLABEJOVÁ, ZUZANA VIDHOLDOVÁ, JAKUB KALOČ “The colour changes of pinewood after weathering” 125 YAROSLAW SOKOLOVSKYY, VOLODYMYR SHYMANSKYI, IGOR KROSHNYI, OLGA MOKRYTSKA, OLEKSANDR STOROZHUK “Modeling of non-isothermal moisture transfer and visco-elastic deformation of wood as a fractal structure” 130 TOMÁŠ SVOBODA, VOJTĚCH VOKATÝ, VLADIMÍR ZÁBORSKÝ “The effect of selected factors on elastic deformation” 138 MACIEJ SYDOR, MARCIN WOŁPIUK “Economic justification for printing threaded joints for wood-based materials” 145 MACIEJ SYDOR, MARCIN WOŁPIUK “The effect of pitch of thread on the force retaining screws in particleboard” 151 JAROSŁAW SZABAN, WOJCIECH KOWALKOWSKI, MARCIN JAKUBOWSKI, TOMASZ JELONEK, ARKADIUSZ TOMCZAK, KAMILA PŁOŃSKA “Modulus of elasticity at static bending in selected provenances of Norway spruce (Picea abies [L.] Karst)“ 157 DOMINIKA SZADKOWSKA, ANDRZEJ RADOMSKI, ANNA LEWANDOWSKA, JAN SZADKOWSKI “Investigations the possibility of cellulose determination in wood particles glued with phenol-formaldehyde resin” 162 MICHAŁ SZCZUKA, ANNA ROZANSKA, WOJCIECH KORYCINSKI “Selected aesthetic properties of traditional finish coatings used in furniture making” 168 KINGA SZENTNER, AGNIESZKA WAŚKIEWICZ, ELŻBIETA LEWANDOWSKA, PIOTR GOLIŃSKI “Enzymatic hydrolysis of different cellulose materials” 176 ARKADIUSZ TOMCZAK, TOMASZ JELONEK, MARCIN JAKUBOWSKI, WITOLD GRZYWIŃSKI, JAROSŁAW SZABAN “The effect of tree slenderness on wood properties in Scots pine. Part I: Basic density and compression strength parallel to grain” 181 ARKADIUSZ TOMCZAK, TOMASZ JELONEK, MARCIN JAKUBOWSKI, WITOLD PAZDROWSKI “The effect of tree slenderness on wood properties in Scots pine. Part II: modulus of rupture and modulus of elasticity” 188 ANDRZEJ TOMUSIAK, IZABELA BURAWSKA, ANDRZEJ CICHY “Comparative compressive strength tests of solid elements and elements glued of small-sized fir wood” 195 ANDRZEJ TOMUSIAK, MAREK GRZEŚKIEWICZ, ANDRZEJ MAZUREK “The impact of the pine annual ring width on the screw withdrawal resistance” 200

3 АЛЕКСЕЙ ЦАПКО “Аспекты влияния органо-минеральных покрытий на огнестойкость древесины” 206 НАТАЛИЯ ТУМБАРКОВА, НЕНЧО ДЕЛИЙСКИ, ЛАДИСЛАВ ДЗУРЕНДА, ИЗАБЕЛА РАДКОВА “Вычисление изменения температуры воздуха во фризере во время замораживания тополиных кряжей” 213 ANNA VILHANOVÁ, MARCELA CIESLAROVÁ “Изменения прочностных свойств гравировой кожи” 220 BOGUSŁAWA WALISZEWSKA, MICHAŁ DUDA, HANNA WALISZEWSKA, AGNIESZKA SPEK-DŹWIGAŁA, AGNIESZKA SIERADZKA “The gross calorific value and the net calorific value of selected exotic wood species” 226 MAŁGORZATA WALKOWIAK, MAGDALENA WITCZAK, WOJCIECH J. CICHY “Thermal modification of lignocellulosic particles to obtain a solid biofuels with improved properties” 230 KRZYSZTOF WARMBIER, LESZEK DANECKI, WŁODZIMIERZ MAJTKOWSKI “Mechanical properties of one-layer experimental particleboards from shoots of tall wheatgrass and industrial wood particles” 237 KRZYSZTOF WIADEREK, ŁUKASZ MATWIEJ, MARIKA DETTLAFF “Impact of structures of selected lounge furniture seats on the comfort of use” 241 MAGDALENA WIĘCKOWSKA, EMILIA GRZEGORZEWSKA “The production potential of the furniture market in Poland” 249 GRZEGORZ WIELOCH, ZDZISŁAW WARMUZ “Dynamic burnishing of wood” 256 WIERUSZEWSKI MAREK, MIRSKI RADOSŁAW “An assessment of the technological parameters of processing medium-size raw material for industrial use” 262 WIERUSZEWSKI MAREK, DERKOWSKI ADAM “The technological parameters of medium-size raw material for mechanical processing” 271 MAREK WIERUSZEWSKI, KATARZYNA MYDLARZ “The influence of the quantitative and dimensional structure of roof truss elements on the material sawing efficiency and production efficiency” 280 PIOTR WITOMSKI, ADAM KRAJEWSKI, “Thermography as a method of structural analysis of historic wooden buildings” 291 PIOTR WITOMSKI, BOGUSŁAW ANDRES, ADAM KRAJEWSKI, MICHAŁ ANISZEWSKI, EWA LISIECKA, ANNA OLEKSIEWICZ “An attempt to determine the amount of mycelium in wood decayed by white-rot fungi Trametes versicolor and brown-rot fungi Coniophora puteana based on ergosterol content” 297 PIOTR WITOMSKI, ADAM KRAJEWSKI, BOGUSŁAW ANDRES, MICHAŁ ANISZEWSKI, EWA LISIECKA, ANNA OLEKSIEWICZ “Changes of cellulose crystallinity determined microscopically in polarised light” 301 ADAM WÓJCIAK “Single item deacidification of paper with dispersion of magnesium hydroxide nanoparticles in alcohol: the problem of process efficiency” 305

4 MARCIN WOŁPIUK, MACIEJ SYDOR “Practical screw withdrawal strength in chosen wood-based composites” 310 MARCIN WOŁPIUK, MACIEJ SYDOR “A review of failure mechanisms in joints of wood-based boards” 315 VLADIMÍR ZÁBORSKÝ, DANIEL RUMAN, VLASTIMIL BORŮVKA, MILAN GAFF “Experimental testing of a selected furniture joint” 324 JANUSZ ZAWADZKI, FLORENTYNA AKUS-SZYLBERG, OLGA BYTNER, MICHAŁ DROŻDŻEK “Chemical properties, density and alkalinity of the black liquor obtained from kraft pulping of a selected fast growing poplar line and of reference species” 328 ALEŠ ZEIDLER, VLASTIMIL BORŮVKA “Effect of within-stem position and site on wood properties of Douglas-fir from the Czech Republic” 335

Board of reviewers: Scientific council :

Piotr Beer Kazimierz Orłowski (Poland) Piotr Boruszewski Ladislav Dzurenda (Slovakia) Piotr Borysiuk Miroslav Rousek (Czech Republic) Dorota Dziurka Nencho Deliiski (Bulgaria) Jarosław Górski Olena Pinchewska (Ukraine) Emila Grzegorzewska Włodzimierz Prądzyński (Poland) Waldemar Jaskółowski Ľubomír Javorek Grzegorz Kowaluk Paweł Kozakiewicz Adam Krajewski Krzysztof Krajewski Sławomir Krzosek Mariusz Mamiński Andrzej Radomski Janusz Zawadzki Tomasz Zielenkiewicz

Warsaw University of Life Sciences Press

e-mail: [email protected] SERIES EDITOR Ewa Dobrowolska ISSN 1898-5912 Marcin Zbieć PRINT: POZKAL

6 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 7-11 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Dynamics of change in the cut-to-length timber market in Poland

KAMILA PŁOŃSKA1, JAROSŁAW SZABAN1, WOJCIECH KOWALKOWSKI2, MARCIN JAKUBOWSKI1 Poznan University of Life Sciences. Departament of Forest Utilisation1, Departament of Silviculture2

Abstract Dynamics of Change in the Cut-To-Length Timber Market in Poland. Continuous demand in the Polish market for various types of wood, resulted in significant improvements in the Government State Forests organisation in Poland. It was required to focus on methods of improving processing and time scales to meet growing demands. One of the new ways to attract and satisfy the market was to introduce Cut-To-Length timber. The aim of this analysis is to demonstrate and explain changes in demand taking place in the Polish market in the past few years. It will also look at changes which brought Cut-To-Length timber offer to the current market. It will show the history and highlight technical improvements made in the past few years, which focus on the ways in which State Forests manufactured and processed recycled wood. This analysis will also aim in highlighting the growth in sales in the past few years. It will focus on the growth of the buyers demand for the multitude of different types of Cut-To-Length timber and engineering behind the cut to leant logging.

Keywords: Cut-To-Length timber, marketing, wood defects

INTRODUCTION The purpose of this analysis is to present changes in the multidimensional wood market in Poland. The analysis will focus on the beginnings of introducing the Cut-To-Length timber on the market. It will present the evolution of the Normative Directives issued by the General Directorate of the State Woods in Poland. The Improvements of procedures in quality control and standard sizes of Cut-To-Length timber (Bielawska 2010, Drabarczyk 2013). It is not easy to establish the exact date from when Cut-To-Length logging was used. Before the current Directives were fully accepted, it was the clients demand that determined the ways of preparation, measurements and logging (Jajor 2010, ). First Official Directive Number 35 issued by the General Director of State Woods in Poland dates to 15th of May 2004. It states the temporary procedures in collection and quality control of the Cut-To-Length coniferous timber. This document targeted mainly the National Market and allowed collection of both assortments of timber – Whole-Tree logging and Cut- To-Length. The flesh of the tree was to be measured based on the length and the top diameter without the bark and then rounded down to the nearest whole cm. In 2010 the General Director issued a directive which was not implemented in its original form. The innovative part of the project was introduction of the Total of quality BC, two classes of length (first from 4.0m and second from 4.1m to 6.0m), and three classes of thickness divided in subclasses. The minimal diameter in the vertex was to be no less than 12cm (Szczerbicki 2010). Real changes happened after the new Directive 53 was introduced 01st January 2013. This Directive tight with the previous one (from 29th June 2012) and formed new obligatory procedures for collection and rotation of pine cut to length. The Directive was also stating the strict guidelines of record-keeping. The new Directive gave guidelines to what can be defined as an acceptable length of timber. An official piece of timber acceptable for trade now measures from 3.0m to 6.0m, and the minimum top diameter without the bark of 14cm. The excess length was to be between 05cm to 10cm. The way of measuring wasn't subject to change, however the actual measurements were to be perfectly accurate (not exceeding 1mm). The Directive was very specific in highlighting 3 classes of thickness in timber: 1K – 14-22cm; 2K – 23-29cm;

7 3K ≥ 30cm. The Directive also provided tables of measurement designed to help to measure the centre flesh of timber. It also contained the mathematical formula which was used to accurately measure the wood. 'Technical Conditions for Cut-To-Length pine timber (WK)' allowed those measurements to be conducted electronically by the recipient. Measurements of the stacks were still compulsory way of calculation of the centre flesh, however the way of measuring the height of the stack was defined and strict procedures were introduced. Measurements of the height of stacks were divided depending on width of the stack (from 6,0m width and above). The Directive from 30th November 2012 lowered the minimal length of timber from 3.0m to 2.7m. Small modifications were made on 01st April 2013, in the new Directive Number 26 issued by the General Director LP. They stated changes to the rules, procedures of collection, rotation and logging of Cut-To-Length pine timber. They also made small changes to the procedures of quality control in State Forests (from 08th of March 2013). 'Technical Conditions for Cut-To-Length pine timber (WK)' no longer contained the formula to measure the thinning of the top of a tree and replaced it with a ready result of 0.7cm/m. The allowed one-sided arrow of rickets was also lowered in the acceptable quality. The good example of this is in class C where the maximum deviation of the axis when measuring the trunk (Kimbar 2011) was lowered from 3cm/m to 2cm/m. Another, currently used Directive number 74 from 27th September 2013 (which came to live on 01st January 2014) changed the total of the quality class BC. The minimal requirements for class BC became the same as for class C. The top level of quality for class B was also strictly establish. The Directive allows production and cutting of timber in lengths from 2.4m (with the mutual agreement between the seller and the buyer). The scope of the thickness was also strictly established 1K – 14-22cm; 2K – 23-32cm and 3K ≥ 33cm. The number of changeable factors in acceptable Cut-To-Length timber and Cut-To- Length logging was also specified and became depended on the length of the shaft. The previous Directive for example allowed for walkway insects on the surface in class C in all types of wood. However, from the 01st of January 2014 surface insects are only allowed in class D.

METHODS This analysis was based on Directives issued by the General Director of the Polish State Forests on processing, cutting and logging of Cut-To-Length pine timber. Also various publications issued by the Official Website of the State Forests in Poland were used. The Official Internet Portal is a valuable source of information on the levels of sales in various types of buyers starting from 2012. The Office for National Statistics in Poland publications (Główny Urząd Statystyczny 2015) also provided data. This analysis was only aiming to explain changes in the process of manufacturing and sales of the Cut-To-Length Pine and Spruce timber. The sales offer is not strictly limited to pine wood. Timber made of deciduous trees is also on offer (e.g. Oak, Birch). Buyers may also find Larch, Fir and Douglas Fir available on the market, but these sales are relatively marginal and therefore not included in this analysis.

RESULTS AND DISCUSSION The intention of this work was to point out the current tendencies when it comes to technologies and market requirements of the Cut-To-Length timber. For this purpose it was necessary to examine Directives issued by the General Directorate LP. The result of this study shows that between 2013 – 2015 the sales had increased by 60% (Fig.1).

Fig. 1 The sale of the Cut-To-Length pine timber between 2013-2015. Source: Information on sales of certain groups of wood issued by the General Directorate LP

In 2015 the sales of the Cut-To-Length pine timber was larger by 1.20mln m3 than two years earlier. The tendency has increased in the sales of the multitude of different types of Cut-To- Length timber boards compared with the sales of the logs (Fig. 2).

Fig. 2 The tendency and changes in sales of Cut-To-Length logs compared with the sales of the boards. Source: Information on sales of certain groups of wood issued by the General Directorate LP

In 2013 the sale of W0 reached 8.9 mln m3, however Wk only 2.0 mln m3 (18% of the general yielding of W0 and Wk). The difference in proportion is clearly visible considering the market situation during those two years. The total sale of W0 fallen down to 8.3 mln m3, and the sale of Wk risen to 3.2 mln m3 (28% of the general yielding of W0 and Wk).

9 In the examined materials it is noticeable that the most frequently sold timber was Pine and Spruce. It is noticeable in the current market that the levels of sales of those two types of wood is constantly increasing. (Fig.3)

Fig. 3 The sales of Pine and Spruce in years between 2013-2015. Source: Information on sales of certain groups of wood issued by the General Directorate LP

CONCLUSIONS The current observable trend on the Polish wood market shows that long-wood logging is being replaced by the multidimensional Cut-To-Length timber. Levels of sale clearly show a growing need for these types of material. State Forests in wanting to meet the needs of the Polish market constantly adjust the processes and the management to continually improve the quality of the sold materials. There’s a noticeable open dialogue between the market industry and State Forests which aims to stabilise the market and improve the forest management.

REFERENCES 1. BIELAWSKA K. 2010: Nowy system klasyfikacji drewna. Głos Lasu nr 2; 6-7. 2. DRABARCZYK J. 2013: Kłodowanie w całych Lasach. Głos Lasu nr 02; 8-11. 3. GŁÓWNY URZĄD STATYSTYCZNY Leśnictwo 2015, Warszawa 2015. 4. JAJOR R. 2010: Wyczekane kłodowanie. W 2012 r. czeka nas nowy system klasyfikacji drewna. Las Polski nr 21; 22-24. 5. KIMBAR R. 2011: Wady drewna. Wyd. R. Kimbar Osie 2011. 6. SZCZERBICKI E. 2010: Liczymy na rozmowę. Nowy system klasyfikacji drewna nie wszystkim się podoba. Las Polski nr 8; 18-19. 7. ZARZĄDZENIE nr 35/2004, 53/2012, 86/2012, 26/2013, 74/2013 Dyrektora Generalnego Lasów Państwowych.

Streszczenie: Dynamika zmian na rynku drewna kłodowanego w Polsce. Rozwój technologii przerobu drewna, stale rosnące zapotrzebowanie na rynku drzewnym, a co za tym idzie, starania o przyspieszenie i usprawnienie procesu przecierania drewna, zobligowały Lasy Państwowe do wprowadzenia w ofercie sprzedaży nowego sortymentu jakim jest drewno kłodowane. W pracy przedstawiono analizę zmian jakie zachodziły w ostatnich kilkunastu latach na rynku drzewnym w Polsce w odniesieniu do drewna kłodowanego. Streszczona została historia zmian zachodzących w warunkach technicznych oraz sposobie odbioru kłód pozyskiwanych przez Lasy Państwowe. Przedstawiono również dane dotyczące zmian w wielkości sprzedaży, tego sortymentu na przełomie ostatnich lat, a także jak zmieniały się proporcje w zakresie sprzedaży drewna wielkowymiarowego kłodowanego a drewna wielkowymiarowego wyrabianego w dłużycach.

Corresponding author:

Kamila Płońska Jaroslaw Szaban, , Marcin Jakubowski Poznań University of Life Science Departament of Forest Utilization Ul. Wojska Polskiego 71 A 60-625 Poznań Poland e-mail: [email protected] e-mail: jaroslaw.szaban2up.poznan.pl e-mail: [email protected]

Wojciech Kowalkowski Poznań University of Life Science Departament of Silviculture Ul. Wojska Polskiego 69 60-625 Poznań Poland e-mail: [email protected]

11 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 12-16 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Analysis of explosive parameters of jatoba dust in wood and furniture industry

MARZENA PÓŁKA, BOŻENA KUKFISZ

Department of Theory Combustion Process and Explosion– The Main School of Fire Service, Warsaw, Poland

Abstract: Analysis of explosive parameters of jatoba dust in wood and furniture industry. In the article are presented research results of the maximum explosion pressure, maximum rate of explosion pressure rise, low explosion limit for jatoba wood dust. Wood particle size was below 200µm. Analysis of explosive parameters of jatoba dust in wood and furniture industry. This research was carried out in 20 dm3 spherical vessel according to PN-EN 14034:2011 standard.

Keywords: dust explosion, industrial dust, industrial safety

INTRODUCTION This paper presents the susceptibility of dust to the initiation of explosion by setting out and analysing values of the maximum explosion pressure (pmax) and the maximal rate of explosion pressure rise (dp/dt)max and low explosion limit (LEL) of cloud dust of jatoba – as a wood exotic species dust in accordance with the standard PN-EN 14034:2011. The conducted experimental tests were used to preventing and/or minimising the consequences of explosions. The susceptibility of wood dust to explosion poses a serious hazard, as it may take place in numerous different technological processes. The exothermal nature of the oxidation reaction, and subsequently the combustion of wood dust, allows additionally easy progress as this dust has a developed proper surface of the material, which increases the contact of the flammable material (dust) with an oxidizer (air) [1-5]. Within the forestry industry, the wood based panel industry is of utmost significance. It is only thanks to the mechanical transformation of the grown wood into wood based panels with defined properties that the requirements of modern wooden and furniture constructions can be optimally complied with. However, the production processes, such as the processing of the wood into chips, fibers or veneer as well as the drying and pressing of the combustible materials to structural elements, hold various risks of fire. Sparks, glowing embers or particles, generated in different plant areas, can easily cause serious fire and explosions.

MATERIALS AND METHODS The study involved dust of exotic wood namely jatoba). The particle size of dust up to 200µm and moisture content 6,03%. The experimental chamber (spherical shaped) with a 20 dm3 capacity is the most crucial laboratory device that is used for testing explosive properties for the determination of an explosion threat connected with a given dust or a mixture of several dusts based on their parameters, i.e. • determination of maximum explosion pressure Pmax of dust clouds in accordance with EN 14034-1:2004+A1:2011 [7], • determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds in accordance with EN 14034-2:2006+A1:2011 [8], • determination of the lower explosion limit LEL of dust clouds in accordance with EN 14034-3:2006+A1:2011 [9],

12 The spherical experimental chamber is an effect of the implementation of a global research standard and has been allowed for both in European standards: EN 14034, and in American ones: ASTM E1226.

RESULTS OF MEASUREMENTS Maximum explosion pressure for jatoba came to 9,37 bar and was observed for 3 concentration 500 g/m . Maximum explosion pressure (pmax) is maximum pressure occurring in a closed vessel during the explosion of an explosive atmosphere determined under specified test conditions. The highest value obtained for a given concentration is seen in figure 1.

Figure 1. Dependence of the maximum explosion pressure for a jatoba dust explosion in a closed vessel a) 5g, b) 10g, c) 15g, d) 20g, e) 25g.

13 Maximum rate of explosion pressure rise (dp/dt)max is maximum value of the pressure rise per unit time during explosions of all explosive atmospheres in the explosion range of a combustible substance in a closed vessel under specified test conditions. Maximum rate of explosion pressure rise for jatoba came to 377,73 bar/s and was observed for concentration 500 g/m3. All measurements values is seen in table 1.

Table 1. Values of maximum rate of explosion pressure rise for jatoba dust for a given concentration Dust concentration 250 500 750 1000 1250 [g] Maximum rate of explosion pressure 50,87 102,53 85,80 99,47 90,29 rise (dp/dt)max [bar/s]

The highest concentration of jatoba dust at which no ignition occurs in three consecutive tests shall be taken as the lower explosion limit and are presented in figure 2. Lower explosion limit for jatoba dust is measured for concentration 30 g/m3. Lower explosion limit is the minimum fuel concentration which is capable of supporting flame propagation in a uniform dust cloud. In the case of dusts, only the lower explosion limit is measurable. An ignition of the dust explosion shall be considered to have taken place, when the measured overpressure (influence of two chemical igniters summary for 2kJ included) relative to the initial pressure is lower than 0,5 bar.

Figure 2. Pressure evolution with time during a dust explosion in a closed vessel for jatoba dust for: a) mass 0,6g –without ignition, b) mass 1,2g –ignition observed.

ANALYSIS OF RESULTS Maximum explosion pressure is determined in a spherical chamber with the volume 20 dm3 by recording the curve „pressure – time”. From the curve the values of maximum explosion pressure and maximum rate of pressure rise are calculated. Maximum explosion pressure for jatoba dust is the range 9,37 bar and for pine dust 7,49 bar. The maximum rate of pressure rise is the range 377,73 bar/s for jatoba dust (exotic wood) to 318,77 bar/s for pine

14 dust (native wood) [6]. The maximum rate of pressure rise in considered to be the best characteristic of explosion severity of dusts because of the so-called ‘cubic law”. The mathematical formulation of the cubic law is: 1/3 (dp/dt)max *V =Kst=cont. The Kst value is considered as a measure of dust explosibility and permits us to calculate the explosion effects in a given volume. This value is the basis of classification of dust explosibility to the classes St1, St2 and St3. According to the general rules, dusts with Kst <200 bar/s belong to the class St1of lowest hazard. The dusts with Kst in the range 201-300 bar/s belong to the class St2 and are more dangerous. The dusts with Kst >300 bar/s are the most dangerous (class St3). Dust specific characteristic value (Kst) for jatoba dust is 102,53 m*bar/s and for pine dust 106,7 m*bar/s. Wood dusts generally belong to the class St1.

The research was supported by the Polish National Centre for Research and Development (NCBiR) - Projects No DOBR-BIO4/050/13009/2013: "Development of system solutions to support the execution of post-fire investigations based on cutting-edge technologies, including technical and IT tools."

REFERENCES 1. Półka. M., Piechocka E., Kukfisz B,. Susceptibility of inflammable industrial dust to ignition from heated surface, Przemysł Chemiczny, 2012, nr 6, s. 1000-1003. 2. B. Kukfisz, M. Półka, Z. Salamonowicz, M. Woliński, The use of selected extinguishing powder for reducing industrial dust explosion impact, Przemysł Chemiczny, 92/10, (2013), 1000-1003. 3. M. Półka, Z. Salamonowicz, M. Woliński, B. Kukfisz, Experimental analysis of minimal ignition temperatures of a dust layer and cloud on a heated surface of selected flammable dust, Elsevier Procedia Engineering 45 (2012) 414-423. 4. M. Półka, Fire and explosion hazards of wooden dust – selected problems, „Ann. Warsaw Agricult. Univ.-SGGW, For and Wood Technol.” 2007, nr 62, p. 163−166. 5. M. Półka, Comparative analysis of minimal ignition temperatures clouds of wooden dusts,„Annals of Warsaw University of Life Sciences – SGGW, Forestry and Wood Technology” 2008, nr 63, p. 201−204. 6. Półka M., Kukfisz B., Woliński M., Salamonowicz Z., Experimental Investigation of Inertization Parameters, Annals of 8th World Conference on Experimental Heat Transfer Fluid Mechanics, and Thermodynamics, Lisbona 16-20.06.2013. 7. PN-EN 14034-1+A1:2011 – Determination of explosion characteristic of dust clouds- Part 1: Determination of the maximum explosion pressure pmax of the dust clouds. 2011. 8. PN-EN 14034-2+A1:2011 - Determination of explosion characteristic of dust clouds- Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of the dust clouds 2011. 9. PN-EN 14034-3+A1:2011 - Determination of explosion characteristic of dust clouds- Part 3: Determination of the lower explosion limit (LEL) of the dust clouds 2011.

Streszczenie: W artykule przedstawiono wyniki badań maksymalnego ciśnienia wybuchu, maksymalna szybkość narastania ciśnienia wybuchu, dolnej granicy wybuchowości pyłów drewna jatoba. Badano pył drewna egzotycznego o wielkości cząstek poniżej 200 urn. Ukazano analizę parametrów wybuchowości pyłu jatoba spotykanego w przemyśle drzewnym i meblarskim. Badana przeprowadzono w 20 dm3 kulistym zbiorniku zgodnie z normą PN -EN 14034 : 2011.

Słowa kluczowe : wybuch pyłu, pył przemysłowy, bezpieczeństwo przemysłowe

Corresponding author:

Author: Marzena Polka, Firm name: The Main School of Fire Service Department of Theory Combustion Process and Explosion, Faculty of Fire Safety Engineering Address: Slowackiego Street 52/54; 01-629 Warsaw; Poland Telephone: 022 56 17 712 E-mail: [email protected]

16 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 17-21 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Application of cellulosic pulps from fast-growing plants in production of packaging papers

KAZIMIERZ PRZYBYSZ1, KAMILA PRZYBYSZ1, BORUSZEWSKI PIOTR2, 1 Natural Fibers Advanced Technologies 2 Warsaw University of Life Sciences - SGGW, Faculty of Wood Technology

Abstract: Application of cellulosic pulps from fast-growing plants in production of packaging papers. Annually, pulp and paper industry in Poland consume approximately 5 million cubic meters of wood. One of the factors limiting increase in production of cellulosic pulp for paper production is insufficient raw material base. Therefore application of fast-growing plants is of utmost interest. Three fast-growing plants like poplar (hybrid 275), larch and miscantus were investigated for application in production of paper. Samples of lignocellulosic material were digested in laboratory-scale installation, consisting of digester and membrane screener. Produced pulps were described by technological parameters like kappa number, chemical composition, water retention value, beatability, dimentional properties of fiber and fines content. Moreover basic properties of paper like breaking length and tear resistance were evaluated.

Keywords: fast-growing plants, pulp, paper, properties of pulp and paper.

INTRODUCTION Constant increase in paper consumption require a great amount of lignocellulosic raw material for production of papermaking pulps. In order to fulfill requirements of paper production and environmental sustainability more than 30% of wood is obtained from certified plantation [1,2]. An alternative option is to use fast growing plants instead of wood or as an addition to wood [3,4]. This paper presents papermaking potential of three fast- growing plants investigated within BIOSTRATEG project.

MATERIALS The following lignocellulosic chips were used for this investigation: • poplar (hybrid 275) • larch (Larix decidua Mill.) • and shredded stems of miscantus (Miscanthus giganteus). The lignocellulosic material was air-dried so as to achieve constant dryness, which was 91,33÷94,19%. It was then digested in laboratory scale digester PD-114B in the following conditions: • active alkali: 26% (to b.d. lignocellulosic material) • sulfidity: 30% • hydromodulus: 4.0 • heating-up time: 2h • digestion temperature: 165°C • digestion time in maximal temperature: 2h • cooling time to ambient temperature: 15 min Optimal digestion parameters have been determined in project PBS1/A8/16/2013 [5]. Pulp obtained after digestion obtained were washed with approximately 50 dm3 of water in the digester then were washed by diffusion for at least 12h. Finally, pulps were washed once again with 30 dm3 of water, defibrated and screened using membrane screener PS-114B. Approximately, the amount of water used for screening was 500÷600 dm3 per sample.

17 The pulps were air-dried and packed in hermetic vials. The following parameters of pulp were evaluated: • pulp kappa number • pulp yield (after digestion and after screening) • fraction of undigested elements Laboratory test sheets were produced with Rapid-Koethen class forming device. Breaking length and tear resistance were determined for these test sheets.

RESULTS Pulp yield for investigated fast-growing lignocellulosic biomass was in most cases similar to pulp yield of birch, beech and poplar. Very significant difference is observed for larch, for which yield is approximately 10% lower than for aspen and birch. Results are presented in figure 1. 60

45 Pulp yield,Pulp % 40

30 Hybrid 275 Miscantus Larch Aspen Birch Beech Figure 1. Pulp yield of investigated fast growing biomass and wood used by paper industry

However, analyzing fraction of undigested elements in the pulp, which are rejected during screening, the highest values are observed for poplar hybrid 275 and for larch. This suggest that probably lignocellulosic material used for pulping could have contained unwanted elements like bark or knags. Therefore it is expected that proper preparation of material for processing may lead to significant increase in yield for hybrid 275 and larch even by 8÷9%. This means that it is possible to achieve yield for larch comparable with values for other pulps and yield for hybrid 275 may be even higher than 50%. Such properties may be very valuable because it means that from 1 metric ton of b.d. wood even more than 40÷50 kg of pulp can be produced in comparison with birch. Results are presented in the figure 2.

18 20

4 Fraction of undigested elements, elements, ofFraction undigested % 2

0 Hybrid 275 Miscantus Larch Aspen Birch Beech Figure 2. Fraction of undigested elements in pulp

Investigation of properties of test sheets of paper indicates that paper produced from pulp after screening, without undigested elements, shows very similar properties. It concerns both static and dynamic tensile properties. Among the investigated fast-growing species the best results were obtained for hybrid 275, which are practically identical like for birch. The lowers values both for breaking length and tear resistance have been observed for larch, however the difference do not seem to be so significant so as to state that this species is not applicable for paper industry. Results for breaking length are presented in figure 3 and for tear resistance in figure 4. 12000

11000

10000

9000

8000

7000 Breaking length,m Breaking

6000

5000

4000 Hybrid 275 Miscantus Larch Aspen Birch Beech Figure 3. Breaking length of paper

19 500

450

400

350

300

250 Tear resistance, resistance, mN Tear 200

150

100 Hybrid 275 Miscantus Larch Aspen Birch Beech Figure 4. Tear resistance of paper

CONCLUSIONS Based on initial results all of the investigated fast-growing plants may be used as substitute for birch in paper industry. In further research, it is necessarily to prepare pulps without such high fraction of undigested elements. It is probably caused by inappropriate preparation of lignocellulosic material for processing. Solving this challenge and increase in pulp yield should have a positive influence on the possibility of using these new lignocellulosic biomass for papermaking application.

REFERENCES

1. CEPI (2014) “CEPI Annual Report” 2. Aulia I.P., (2003) “The future of plantation forests and forest-based industry in Indonesia”, Proceedings of IUFRO 5.11-5.12 3. Kissinger M., et al (2007) “Wood and non-wood pulp production: Comparative ecological footprinting on the Canadian prairies” Ecological Economics, 62, 3–4, 552– 558 4. Kovacs I., (1992) “Hemp as a possible raw material for paper industry” Cellulose Chemistry and Technology, 26, 627-635 5. -, (2016) Project PBS1/A8/16/2013 Final report

The authors gratefully acknowledge that this work was financially supported by the project BIOSTRATEG/298537/7/NCBR/2016 founded by National Centre for Research and Development, Poland (NCBiR).

Streszczenie: Zastosowanie mas włóknistych z roślin szybkorosnących do produkcji papieru. Przemysł celulozowo-papierniczy zużywa około 5 mln metrów przestrzennych drewna rocznie. Jednym z czynników ograniczających wzrost produkcji mas włóknistych do celów papierniczych jest ograniczona baza surowcowa. W związku z tym zastosowanie do produkcji mas włóknistych roślin szybkorosnących stanowi bardzo interesującą możliwość. Trzy gatunki roślin szybko rosnących takich jak topola hybryda 275, modrzew i miskantus zostały przebadane pod względem możliwości zastosowania do produkcji papieru. Materiał ligninocelulozowy został roztworzony w laboratoryjnej instalacji składającej się z warnika i sortownika membranowego. Dla otrzymanych mas określono podstawowe parametry takie jak stopień roztworzenia, skład chemiczny, WRV, mielność, właściwości wymiarowe włókien i zawartość frakcji drobnej. Ponadto określono podstawowe właściwości papieru takie jak samozerwalność i opór przedarcia.

Corresponding author:

Kazimierz Przybysz Błękitna 42A 93-322 Łódź, Poland email: [email protected] phone: 603-187-429

21 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 22-25 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Evaluation of dimensional properties of cellulosic fibers as a tool for swift, initial evaluation of papermaking potential of pulp

KAMILA PRZYBYSZ, KAZIMIERZ PRZYBYSZ. Natural Fibers Advanced Technologies

Abstract: Evaluation of dimensional properties of cellulosic fibers as a tool for swift, initial evaluation of papermaking potential of pulp. Papermaking pulps are the main ingredient of paper. In order to achieve appropriate properties of paper it is necessary use fibers of given dimensional properties. Modern methods of evaluation of fibers dimensional properties allow to measure not only fiber length but also fiber width, kink, curl and many other parameters. Performing such test is a relatively fast procedure and results are very accurate. In this paper application of such measurement was validated for typical sulphate pulp, semichemical pulp and whitewater from paper machine.

Keywords: pulp, paper, fiber length, fiber width, curl, kink

INTRODUCTION Evaluation of properties of pulp and paper is a very complex task. There are numerous properties of paper, which should be evaluated in order to estimated papermaking potential of given pulp. According to scientific literature, number of basic properties of pulp and paper ranges a few to oven a dozen [1,2]. Moreover, most of these test are very time consuming and requires specialized equipment. It results in very high cost of determination of these properties. Not only cost-intensity of measurement is the biggest problem, but also time of measurement is extremely important. Therefore, methods which are not the most accurate but enable to provide results within minutes overpass methods which provide very accurate results but requires more time. This situation is observed for example in evaluation of refining progress. Freeness measured by Schopper-Reigler degrees is for sure less accurate than water retention value. However, time required to determine freeness is about 3 minutes, which is at least 30 times shorter than determination of water retention value. Due to this reason, in industrial condition only freeness is regularly measured. Recent development of image processing technology led to development of devices that can be successfully used for determination of dimensional properties of fibers. Evaluation of these properties is nowadays very fast, and accuracy of results is also very good.

METHOD Dimensional properties of fibers were evaluated using Morfi Compact Black Edition device (Figure 1). This device complies all requirements of ISO 16065-2 (2014) standard. In a single measurement the following properties of fibers are determined: • distribution of fiber length, divided in ten user defined classes • distribution of fiber width, divided in ten user defined classes • distribution of fiber kink, divided in ten user defined classes • distribution of fiber curl, divided in ten user defined classes • average fiber length calculated as arithmetical and length weighted value • average fiber width, kink and curl • fiber coarsness • number of fibers in 1 gram • fines content calculated as length, area and weighted length.

Figure 1. Morfi Compact Black Edition with computer

MATERIALS The following cellulosic pulps were used in this research: - commercial sulphate bleached pine pulp - sulphate unbleached pine pulp - semichemial (NSSC) birch pulp - whitewater from technological line of paper mill

RESULTS The main advantage of evaluation of dimensional parameters using Morfi Compact Black is automatic determination of concentration of suspension. Suggested concentration of sample 0,04g/dm3. The device operate properly even for samples of concentration between 0,004 to 0,1 g/dm3. The base for investigation is a series of photographs taken by the device. Example of such photo is presented in the figure 2.

Figure 2. Image used for analysis taken by the device

23 Results obtained by the device are recalculated and the final analysis is a series of charts and text file consisting all the results. These results may be further recalculated and processed. An example of these results for fiber length and fiber width is presented in the figure 3.

Fraction,% 6

0 200 622 1044 1467 1889 2311 2733 3156 3578 4000-> -622 -1044 -1467 -1889 -2311 -2733 -3156 -3578 -4000 Fiber length, µm

Figure 3. Fiber length distribution for sulphate pine pulp

15 Fraction,% 10

0 5-13 13-21 21-29 29-36 36-44 44-52 52-60 60-> Fiber width, µm

Figure 4. Fiber width distribution for sulphate pine pulp

Moreover, the following results are calculated within the measurement: • Average arithmetical fiber length: 1303 µm • Average fiber length-weighted length: 1938 µm • Mean fibre width: 28,8 µm • Mean fibre coarseness: 0,1571 mg/m • Average kink number 1,816 • Average kink angle: 132,025 • Kinked fibre content: 52,536 % • Mean fibre curl index: 12,761 %

24 • Macro Fibrillation index: 0,29 % • Broken fibre content: 33,635 %

CONCLUSIONS The proposed methodology enable to determine wide range of fiber dimensional properties both for sulphate pulp, semichemical pulps and even whitewater from the system. Preparation of sample is very easy, because the exact concentration is calculated by the device. This eliminate errors in parameters for which concentration is used for calculation i.e. coarseness, number of fibers in one gram and fines fraction content.

REFERENCES

1. CEPI (2014) “CEPI Annual Report” 2. Kissinger M., et al (2007) “Wood and non-wood pulp production: Comparative ecological footprinting on the Canadian prairies” Ecological Economics, 62, 3–4, 552– 558 3. Pulps — Determination of fibre length by automated optical analysis — Part 2: Unpolarized light method

The authors gratefully acknowledge that this work was financially supported by the project BIOSTRATEG/298537/7/NCBR/2016 founded by National Centre for Research and Development, Poland (NCBiR).

Streszczenie: Ocena parametrów wymiarowych włókien mas włóknistych jako narzędzie do wstępnej oceny zdolności papierotwórczej. Papiernicze masy włókniste są podstawowym składnikiem papieru. W celu uzyskania odpowiednich właściwości papieru, konieczne jest wykorzystanie mas włóknistych zawierających włókna o określonych właściwości wymiarowych. Współczesne metody oceny parametrów wymiarowych włókien pozwalają zmierzyć nie tylko długość włókien, ale także ich szerokość, zagięcia, stopień skędzierzawienia i wiele innych parametrów. Wykonanie takich pomiarów jest szybkie a uzyskane wyniki bardzo dokładnie. W artykule przedstawiono i zwalidowano możliwość wykonania takich pomiarów dla mas siarczanowych, mas półchemicznych a nawet wód podsitowych w papierni.

Corresponding author:

Kamila Przybysz Mochnackieg 9/13/22 93-160 Łódź, Poland email: [email protected] phone: 605-401-527

25 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 26-31 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

TiO2-SiO2 as a potential agent in wood preservation.

1RATAJCZAK IZABELA, 1KOWALEWSKI PAWEŁ, 1WOŹNIAK MAGDALENA, 1SZENTNER KINGA, 2NOWACZYK GRZEGORZ, 3MICHAŁ KRUEGER, 4COFTA GRZEGORZ

1Poznań University of Life Sciences, Department of Chemistry, Wojska Polskiego 75, PL-60625 Poznan, Poland 2Adam Mickiewicz University in Poznan, NanoBioMedical Centre, Umultowska 85, PL 61614 Poznań, Poland 3Adam Mickiewicz University in Poznan, Institute of Prehistory, Umultowska 89D, PL-61614 Poznan, Poland 4Poznań University of Life Sciences, Institute of Chemical Wood Technology, Wojska Polskiego 38/42, PL- 60637 Poznan, Poland

Abstract: TiO2-SiO2 as a potential agent in wood preservation. Hydrophobic titanium dioxide (TiO2) was successfully grown on a wood surface. Scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDX), X-ray fluorescence (XRF), atomic absorption spectrometry (AAS) and Fourier transform infrared spectroscopy (FTIR) were employed to determine the characteristics of grown TiO2-SiO2 and its hydrophobicity. SEM, XRF, AAS and FTIR confirmed that TiO2 was chemically bonded to the wood surface through the combination of hydrogen groups. Results from the combined analyses of SEM and EDX, AAS, FTIR and XRF demonstrated that the TiO2-SiO2 layer was chemically bonded to wood surface.

Keywords: tetraethoxysilane, titanium(IV) isopropoxide, SEM EDX, XRF, AAS, FTIR, Coniophora puteana

INTRODUCTION Numerous types of silicon compounds have been applied to improve properties of wood. They are used in numerous applications, including pulp and paper and ceramics industries, and as adhesion promoters between organic and inorganic materials [Kartal et al. 2009]. Silicon compounds exhibit high hydrophobicity due to the presence of organic groups. Many wood properties, such as fungal resistance, dimensional stability, fire and water resistance, are improved by the application of this group of chemical compounds [Donath et al. 2004, Sebe, Brook 2001, Panov, Terziev 2009, Sebe, De Jeso 2000, Tingaut et al. 2006]. Organosilanes are mixed with other substances, such as natural oils, potassium carbonate or titanium, in order to improve wood properties [Mahr et al. 2012, Mazela et al. 2015]. A mixture of TiO2 and SiO2 reduces copper leaching from treated wood [Mahr et al. 2013]. Increased interest has recently been observed in the development of inorganic coatings consisting of SiO2 and TiO2 on the polymer surface, driven by their excellent characteristics of mechanical and thermal performances, optical behaviour and bactericidal resistance [Pandey et al. 2005, Sun et al. 2010]. The formation of a TiO2 layer on wood surface can significantly improve properties of fire and antifungal resistance as well asaging durability [Miyafuji, Saka 1997, Schmalzl, Evans 2003, Mahltig et al. 2008]. The aim of this study was to evaluation fungistatic properties wood treated with organosilicon and titanium mixture against C. puteana and preliminary determination character of bonds between wood and constituents of examined formulation.

MATERIALS AND METHODS Chemicals The protecting formulation was prepared by dissolving basic reagents: tetraethoxysilane (TEOS) Si(OC2H5)4 in acidic ethanol and titanium(IV) isopropoxide (TIP) Ti[OCH(CH3)2]4 in acidic 2-propanol. Next all reagents were mixed at a 1:1 mass ratio and heated to 50-70 °C for 3 h.

Wood material and impregnation Wood samples of 40×15×5 mm (the last dimension along the grain) were prepared from Scots pine sapwood (Pinus sylvestris L.) for biological tests. All samples were free of any defects or fungal infections. The samples were impregnated in vacuum for 15 minutes and then 2 hours at atmospheric pressure. For complete hydrolysis samples were stored for 7 days under a moist atmosphere (under 75% relative humidity) and for 10 days under normal conditions. Final curing was provided by drying at 103oC for 24 hours. Half of the samples were subjected to the leaching procedure by keeping the samples immersed in distilled water of (20 ± 2) °C at a proportion of approx. 5 volumes of water to 1 volume of wood. Within 7 days the water was replaced 10 times.

Biological tests Treated wood samples were exposed against the fungus C. puteana (Schumacher ex Fries) Karsten (BAM Ebw. 15) according to the modified EN 113 standard. Weight loss and the moisture content of wood samples were determined after 8 weeks of exposure.

Atomic Absorption Spectrometry (AAS) Wood samples were milled to powder and representative samples of 0.5 g powder were collected from the prepared material. Samples were mineralised in a semi-closed Marsexpress microwave mineralization system (CEM Corporation, USA). The silicon and titanium contents were analysed using the Duo AA280FS/AA280Z spectrometer (Agilent Technologies, Australia). The final results were average values of three simultaneous measurements.

Fourier Transform Infrared Spectroscopy (FTIR) Wood powder samples were mixed with KBr at a 2/200 mg ratio. Spectra were registered using an Infinity spectrophotometer with Fourier transform (Mattson Technology, USA) at a range of 500-4000 cm-1 at a resolution of 2cm-1, registering 64 scans.

Scanning Electron Microscopy (SEM) Morphology was examined under a Scanning Electron Microscope (SEM) JEOL 7001F (SEI detector, maximum 30 kV accelerating voltage, Japan). Before experiments the samples were well dried and sputtered with a thin layer of gold. The composition of the samples was investigated using energy dispersive X-ray microanalysis (EDX) with an X-ray equipped SEM.

X-ray fluorescence (XRF) Silicon and titanium contents on the surface of treated wood samples were analysed using portable X-ray fluorescence spectrometer Bruker Tracer III-SD. Quantitative values of silicon on treated wood surfaces were determined using the MajMudRock calibration method.

RESULTS AND DISCUSSION Results of mycological tests of wood impregnated with the tested formulation are presented in Table 1. The average mass loss of control samples was about 50%, which indicates decay activity of the analysed fungus. Treated wood after leaching demonstrated good resistance against C. putena and may be classified as durability class 1 (“very durable”), according to the EN 350 standard. The presented results of biological activity of wood treated with TiO2-SiO2 formulation after leaching lead to better fungistatic properties.

27 Table 1. Mass loss and retention of treated wood Retention Sample WL [%] RSD DC [kg/m3] TS 140.65 5.9 0.3 Unleachedtreatedwood 1 CS - 50.9 3.7 TS 147.33 1.1 0.2 Leached treated wood 1 CS - 48.1 4.1 TS – tested sample, CS – control sample, RSD – relative standard deviation, WL – weight loss, DC – durability class acc. to the EN 350 standard

Concentrations of silicon and titanium in the entire volume and on the surface of treated wood are presented in Table 2. Silicon and titanium contents analysed using atomic absorption spectrometry are very similar for unleached and leached wood, which may suggest chemical interaction between wood and the protecting formulation. The presence of Si and Ti on the surface of treated wood was confirmed by X-ray fluorescence spectroscopy and scanning electron microscopy.

Table 2. Silicon and titanium contents on the surface and the entire volume of treated wood X-ray fluorescence spectroscopy (XRF) Sample Silicon contents [ppm] Titanium contents [ppm] Unleached wood 7.63 ± 0.19 5.39 ± 0.08 Leached wood 4.90 ± 0.15 3.50 ± 0.05 Scanning Electron Microscope (SEM) Sample Silicon content [%] Titanium content [%] Unleached wood 1.12 4.82 Atomic absorption spectrometry (AAS) Sample Silicon content [mg/kg] Titanium content [mg/kg] Unleached wood 237.8 ± 2.75 1926.7 ±33.70 Leached wood 219.7 ± 1.94 1780.9 ± 34.22 Concentration of silicon and titanium in control, untreated wood samples was under detection.

In order to confirm stability of preparation bonding with wood and to compare the results with data from analyses (XRF, SEM, AAS) of silicon and titanium presents (Fig. 1) spectra of untreated pine wood (A), impregnated wood (B) and treated wood after leaching (C).

Figure 1. Spectra of wood (A), treated wood (B), treated wood after leaching (C)

The appearance of a new band (Fig. 1) in the case of impregnated wood samples at 720 cm-1 (Si–C, Si–O) and a decrease in the intensity of the bandat 1740 cm-1 (C=O),as well as a lack of changes in spectra of wood after the leaching process may indicate permanent bonding of the preparation components with wood. The peaks at 2920 and 2850 cm-1 correspond to –CH3 asymmetric and –CH2 symmetric stretch vibrations, respectively [Sun et al. 2011]. The origin of –CH3and –CH2 is the incorporated into the TiO2 surface. These groups provide hydrophobicity of treated wood [Pandey 1999]. The peak of 580 cm-1 was characteristic of TiO2 grown on the wood surface and it is attributed to the Ti–O stretch vibration. The peak at 3500-3300 cm-1corresponding to the stretching vibrations of the hydroxyl groups in the treated wood shifted to lower wavenumbers, indicating an interaction between hydroxyl groups of wood surface and the grown TiO2 through the hydrogen bond. Similar studies [Saka, Ueno 1997, Mahltig et al. 2008, Tshabalala, Sung 2007] demonstrated that cellulosic fibres of wood could act as hydrophilic substrates to nucleation and growth of inorganic particles, such as SiO2 and TiO2 [Sun et al. 2011].

CONCLUSIONS The results of preliminary research indicate, that TiO2-SiO2 formulation can be new protecting agent demonstrate low toxicity but research should be extended to other factor caused wood degradation. These silicon and titanium contents and FTIR analyses can suggest stability of silane and titanium bonds with wood and hydrophobisation, when TiO2-SiO2 is used as a component of the protecting formulation applied on the pine wood. Hydrophobic SiO2-TiO2 chemically bonded to the wood surface through hydrogen groups.

REFERENCES 1. DONATH S., MILITZ H., MAI C. 2004: Wood modification with alkoxysilanes. Wood Sci. Technol. 38; 555-566

29 2. KARTAL S.N. YOSHIMURA T., IMAMURA Y. 2009: Modification of wood with Si compounds to limit born leaching from treated wood and to increase termite and decay resistance. Int. Biodeter. Biodegr. 63; 187-190 3. MAHLTIG B.,SWABODA C., ROESSLERA., BÖTTCHER H. 2008: Functionalising wood by nanosol application.J. Mater. Chem., 18, 3180-3192 4. MAHR M.S., HUBERT T., SCHARTEL B., BAHR H., SABEL M., MILITZ H. 2012: Fire retardancy effects in single and double layered sol-gel derived TiO2 and SiO2 – wood composites. J. Sol-Gel Sci. Technol. 64; 452-463 5. MAHR M.S., HUBERT T., STEPHAN I., BUCKER M., MILITZ H. 2013: Reducting copper leaching from treated wood by sol-gel derived TiO2 and SiO2 deposition. Holzforschung 67(4); 429-435 6. MAZELA B., BRODA M., PERDOCH W., GOBAKKEN L.G., RATAJCZAK I., COFTA G., GRZEŚKOWIAK W., KOMASA A., PRZYBYŁ A. 2015: Bio-friendly preservative systems for enhanced wood durability – the first periodic raport on DURAWOOD project. The International Research Group on Wood Protection. IRG/WP 15-30677 7. MIYAFUJI H., SAKA S. 1997: Fire-resisting properties in several TiO2 wood-inorganic composites and their topochemistry. Wood Science and Technology31, 449-455 8. PANDEY K.K. 1999: A study of chemical structure of soft and hardwood and wood polymers by FTIR. Journal of Applied Polymer Science 71; 1969-1975 9. PANDEY J.K., REDDY K R., KUMAR A.P., SINGH R.P. 2005: An overview on the degradability of polymer nanocomposites. Polymer Degradation and Stability 88 (2): 234- 250 10. PANOV D., TERZIEV N. 2009: Study on some alkoxysilanes used for hydrophobation and protection of wood against decay. Int. Biodeter. Biodegr. 63; 456-461 11. SAKA S., UENO T. 1997: Several SiO2 wood-inorganic composites and their fire- resisting properties. Wood Science and Technology 31; 457-466 12. SCHMALZL K.J., EVANS P.D. 2003: Wood surface protection with some titanium, zirconium and manganese compounds. Polymer Degradation and Stability, 83; 409-419 13. SEBE G. BROOK M.A. 2001: Hydrophobization of wood surfaces: covalent grafting of silicone polymers. Wood Sci. Technol. 35; 269-282 14. SEBE G. DE JESO B. 2000: The dimensional stabilisation of maritime pine sapwood (Pinus pinaster) by chemical reaction with organosilicon compounds. Holzforschung 54; 474-480 15. SUN Q., YU H., LIU Y., LI J., CUI Y., LU Y. 2010. Prolonging the combustion duration of wood by TiO2 coating synthesized using cosolvent-controlled hydrothermal method. Journal of Materials Science, 45, 6661-6667 16. TINGAUT P., WIEGENAND O., MAI C., MILLITZ H., SÈBE G. 2006: Chemical reaction of alkoxysilane molecules in wood modified with silanol groups. Holzforschung 60; 271-277 17. TSHABALALA M., SUNG L. 2007: Wood surface modification by in-situ sol-gel deposition of hybrid inorganic-organic thin films. J. Coat. Technol. Res., 4 (4) 483-490

30 Streszczenie: TiO2-SiO2 jako potencjalny środek ochronny do drewna. W pracy określono skuteczność preparatu zawierającego mieszaninę TiO2-SiO2 chroniącego drewno przed działaniem grzyba C. puteana. Ponadto analizowano oddziaływania chemiczne pomiędzy preparatem a drewnem sosny (Pinus sylvestris L.). Badaniom poddano próbki drewna sosny impregnowane w warunkach obniżonego ciśnienia 0.1 MPa. Proces wymywania próbek prowadzono wg normy EN 84, natomiast badania mikologiczne wg normy EN 113. Wykorzystano następujące techniki analityczne: absorpcyjną spektrometrię atomową (AAS), skaningową mikroskopię elektronową (SEM) i spektroskopię fluorescencji rentgenowskiej (XRF). Ponadto, analizę strukturalną drewna sosny po impregnacji preparatem SiO2-TiO2 oraz po wymyciu wodą wykonano metodą spektroskopii w podczerwieni. Przedstawione wyniki wskazują na oddziaływanie badanego preparatu z drewnem czego dowodem są widoczne pasma w widmie FTIR charakterystyczne dla drgań wiązania Si-C, Si-O w zakresie 720 cm-1 oraz Ti-O w zakresie 580 cm-1. Przeprowadzone analizy chemiczne (AAS, SEM EDX, XRF) wskazują, że opracowany preparat wykazuje chemiczne odziaływanie z drewnem, co potwierdzają zbliżone wyniki stężenia krzemu oraz tytanu w próbkach drewna sosny po impregnacji oraz po procesach starzeniowych.

Acknowledgement The part of the study was supported by financial resources of the research project no DEC- 2013/09/B/HS3/00630.

Corresponding author:

Izabela Ratajczak Poznań University of Life Sciences, Department of Chemistry Wojska Polskiego 75, PL-60625 Poznań, Poland e-mail: [email protected]

31 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 32-37 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Investigation of the use of impregnating formulation with propolis extract and organosilanes in wood protection – chemical analyses. Part I: FTIR and EA analyses.

1WOŹNIAK MAGDALENA, 1RATAJCZAK IZABELA, 1KINGA SZENTNER, 1IWONA RISSMANN, 2GRZEGORZ COFTA

1Poznań University of Life Sciences, Department of Chemistry, Wojska Polskiego 75, PL-60625 Poznan, Poland 2Poznań University of Life Sciences, Institute of Chemical Wood Technology, Wojska Polskiego 38/42, PL- 60637 Poznan, Poland

Abstract: Investigation of the use of impregnating formulation with propolis extract and organosilanes in wood protection – chemical analyses. Part I: FTIR and EA analyses.The paper presents the first part of chemical results: structural changes in treated wood exposed to C. puteana using Fourier Transform Infrared Spectroscopy (FTIR) and comparison the elemental composition of treated wood before and after exposure to the analysed fungus. Slight differences in nitrogen, carbon, hydrogen and oxygen contents recorded in wood samples following impregnation, leaching and exposure to fungal degradation, confirm the permanent character of bonding between the formulation and wood. The stable character of Si-C and Si-O bonds was shown in IR spectra and discussed in this paper.

Keywords: propolis, organosilanes, elemental analysis, FTIR

INTRODUCTION Propolis as a natural material, collected by bees from different trees, shrubs and plants, is characterized by a very complex chemical composition. All countries and regions have diversified vegetation and ecological conditions, which have an effect on differences in the composition of propolis collected from various geographical regions. Propolis is composed of 50% resin and vegetable balsam, wax, essential and aromatic oils, pollen and other substances, including organic and mechanical debris [Kędzia 2006, Uzel et al. 2005]. Extracts of propolis possess numerous biological properties, such as antibacterial, antifungal and anticancer, and for this reason the chemical composition has been extensively investigated [Castaldo and Capasso 2002, Kujumgiev et al. 1999]. Nowadays more than 300 chemical compounds have been identified in propolis samples from different geographical origins, such as polyphenols (flavonoids, phenolic acids and their esters, phenolic aldehydes, alcohols and ketones), steroids, terpenoids, amino acids, sugars, fatty acids and micro- and macroelements [Kędzia 2006, Kujumgiev et al. 1999, Mahammadzadeh et al. 2007, Uzel et al. 2005]. The most popular constituents detected in propolis from Europe include flavonoids, such as pinocembrin, naringenin, pinostrobin, chrysin, apigenin, galangin and kaempferol as well as phenolic acids and their esters including caffeic acid, coumaric acid, ferulic acid, cinnamylcaffeate and phenethylcaffeate [Ahn et al. 2007, Kędzia 2006, Kumazawa et al. 2004, Uzel et al. 2005]. Volatile constituents of propolis are identified mainly as eudesmol, eugenol, vanillin, cadinene, pinene and geraniol [Bankova et al. 2014, Melliou et al. 2007]. There are numerous other constituents found in propolis samples, such as fatty acids (lauric, myristic, oleic and stearic acids) and chemical elements including calcium, magnesium, potassium, iron and zinc [Gong et al. 2012, Uzel et al. 2005]. Wood samples treated with propolis extract showed resistance against wood destroying fungi, such as Coniophora puteana and Poria placenta [Jones et al. 2011]. Moreover, pine wood impregnated with the propolis and silane formulation exhibited resistance against C.

32 puteana [Woźniak et al. 2015]. Protection of wood against water is one of the most important functions of silicon compounds, but they are also used as multifunctional additives to protecting formulations. Many wood properties, such as fire resistance and durability, are improved by the application of silanes [Mai and Militz 2004, Tingaut et al. 2006]. The aim of this part of the study was to determine structural changes in treated wood exposed to C. puteana using Fourier Transform Infrared Spectroscopy (FTIR) and compare the elemental composition of treated wood before and after exposure to the investigated fungus.

MATERIALS AND METHODS Chemicals The formulation used in this study consisted of 15% ethanolic propolis extract, and two organosilanes: methyltrimethoxysilane (MTMOS) CH3Si(OCH3)3 (Siltec, Poland) and (3- (trimethoxysilyl)propyl methacrylate) (MPTMOS) H2C=C(CH3)CO2(CH2)3Si(OCH3)3 (Sigma Aldrich, Germany) at a 5% concentration. Wood material Wood samples used in this study were Scots pine sapwood treated with examined formulation and half of samples were leached according to standard EN 84. The treated wood was exposed to C. puteana, according to the modified standard EN 113. Fourier Transform Infrared Spectroscopy analysis (FTIR) Wood samples were homogenised using a ball mill (Ika, Germany) and the homogenous material in the form of powder with grains sized 0.2 mm was used for analyses. Wood powder was mixed with KBr (Sigma-Aldrich, Germany) at a 1/200 mg ratio. Spectra were registered using an Infinity spectrophotometer with Fourier transform at a range of 500-4000 cm-1 at a resolution of 2 cm-1, registering 64 scans (Mattson Technology, USA). Elemental analysis (EA) Powdered wood samples were dried to dry weight at a temperature of (105±2) °C and used for the determination of their elemental contents. Contents of carbon, nitrogen, hydrogen, oxygen and sulphur were analysed using the Thermo Scientific Flash 2000 CHNS/O Analyzer (Thermo Fisher Scientific, USA). Instruments were calibrated with the certified reference material (CRM) – Alfalfa (Elemental Microanalysis Ltd., UK)for CHNS analyses with the Benzoic acid standard (Thermo Fisher Scientific, USA) for oxygen determination. The correctness of the calibration method was verified using reference material Birch Leaf (Elemental Microanalysis Ltd., UK) for CHNS analyses and the Methionine standard (Thermo Fisher Scientific, USA) for oxygen determination.

RESULTS AND DISCUSSION Table 1 presents contents of nitrogen, carbon, hydrogen and oxygen in unleached and leached wood samples before and after exposure to C. puteana. Results for treated wood before and after mycological tests against the analysed fungus differed from those of untreated wood. This may indicate fungistatic properties of the propolis and silane formulation, whichprotect against the destroying action of C. puteana.

Table 1. Contents of nitrogen, carbon, hydrogen, oxygen and sulphur in treated wood* NITROGEN CARBON HYDROGEN Sample OXYGEN [%] [%] [%] [%] Untreated wood 0.074 ± 0.008 47.389 ± 0.157 6.309 ± 0.097 41.387 ± 0.279 EN 84 0.063 ± 0.013 47.359± 0.162 6.092 ± 0.099 43.394± 0.379 Treated wood 0.075 ± 0.005 48.992± 0.270 6.248 ± 0.014 39.983± 0.069 EN 84 0.061 ± 0.003 49.710± 0.001 6.341 ± 0.026 39.394± 0.371

33 The results of wood after exposure to C. puteana Untreated wood 0.358 ± 0.009 49.603 ± 0.040 5.916 ± 0.149 41.758± 0.029 EN 84 0.377 ± 0.012 49.478 ± 0.048 5.875 ± 0.192 41.360± 0.595 Treated wood 0.114 ± 0.003 49.880± 0.057 6.302 ± 0.058 37.961± 0.056 EN 84 0.113 ± 0.011 50.329± 0.165 6.347 ± 0.011 37.348± 0.263 EN 84 – wood after leaching procedure, according to EN 84 standard *sulphur content was under detection limits

In order to confirm stability of the preparation bonding with wood and to compare the results with data from elemental analyses, Fig. 1 presents spectra of untreated pine wood (A), impregnated wood (B) and treated wood after leaching (C).The appearance of new spectra (Fig. 1) in the case of impregnated wood samples at 2940 and 2930 cm-1 (CH stretch in methyl and methylene groups), 1720 and 1705 cm-1 (C=O stretch in carbonyls and in ester groups), 830 and 765 cm-1 (Si–C, Si–O asymmetric stretch), as well as a lack of changes in spectra of wood after the leaching process may indicate permanent bonding of the preparation components with wood.

Figure 1. Spectra of wood (A), treated wood (B), treated wood after leaching (C)

The infrared spectroscopy measurement was also used in order to determine the degree of the effect of the cellar fungus C. puteana on wood. Interpretation of IR spectra was based on studies [Pandey, Pitman 2003,Irbe et al. 2006, 2011]. Figure 2 presents a comparison of treated wood spectra (A) with the spectrum of treated wood exposed to C. puteana (B). Figure 3 presents a comparison of IR spectra of treated wood after leaching (A) and treated wood after leaching exposed to the fungus (B).

Figure 2. Spectra of treated wood (A), treated wood after fungal exposure (B)

In the spectra of treated wood we may observe clear changes in the intensities of carbohydrate bands (fig. 2b). These bands are connected mainly with vibrations in the fingerprint region, namely 1375 cm-1 (deformation of C-H- cellulose and hemicellulose) and 1160 cm-1 (C-O-C vibration in cellulose and hemicellulose). In the spectrum of treated wood exposed to the fungus (B) the intensity of these bands decreases as compared with the spectra of treated wood (A). In Figure 3 the effect is the opposite. In the spectrum of treated wood after leaching exposed to the fungus (B) the intensity of these bands increases as compared with the spectra of treated wood after leaching (A). Moreover, spectra A and B overlap, which is particularly evident in the range of 1800-800 cm-1, presented in Fig. 3b.

Figure 3. Spectra of treated wood after leaching (A), treated wood after leaching and fungal exposure (B)

Spectra of impregnated wood after leaching exposed to C. puteana (B) showed no changes in values of absorbance. A lack of changes within carbohydrate groups may indicate a positive effect of the wood protection system. It is visible only for the samples after leaching, indicating a positive effect of hydrolysis, as a consequence followed by the fixation of the formulation in the wood samples.

CONCLUSIONS The stable character of Si-C and Si-O bonds was shown in IR spectra and discussed in this paper. The characteristic vibrations of bonds between silicon and carbon and oxygen were observed in spectra of wood both before and after leaching at 830 and 765 cm-1. In those spectra the bands coming from carbonyl groups from (3-(trimethoxysilyl)propyl methacrylate) and propolis were found at 1720 and 1705 cm-1. Moreover, the reduction in the intensity of IR spectra was compared with literature data for treated wood after leaching exposed to the fungus degradation in comparison with treated wood at 1375 and 1160 cm-1. Slight differences in nitrogen, carbon, hydrogen and oxygen contents recorded in wood samples following impregnation, leaching and exposure to fungal degradation confirm the permanent character of bonding between the formulation and wood.

REFERENCES 1. AHN M.R., KUMAZAWA S., USUI Y., NAKAMURA J., MATSUKA M., ZHU F., NAKAYAMA T. 2007: Antioxidant activity and constituents of propolis collected in various areas of China. Food Chem. 101; 1383-1392 2. BANKOVA V., POPOVA M., TRUSHEVA B. 2014: Propolis volatile compounds: chemical diversity and biological activity: a review. Chem. Cent. J. 8(28); 1-8

35 3. CASTALDO S., CAPASSO F. 2002: Propolis, an old remedy used in modern medicine. Fitoterapia 73(1); S1-S6 4. GONG S., LUO L., GONG W., GAO Y., XIE M. 2012: Multivariate analyses of element concentrations revealed the groupings of propolis from different regions in China. Food Chem. 134; 583-588 5. IRBE I., ANDERSONE I., ANDERSONS B., NOLDT G., DIZHBITE T., KOURNOSOVA N., NUOPPONEN M., STEWART D. 2011: Characterisation of the initial degradation stage of scots pine (Pinus sylvestris L.) sapwood after attack by brown- rot fungus Coniophora puteana. Biodegradation 22; 719-728 6. IRBE I., ANDERSONS B., CHIRKOVA J., KALLAVUS U., ANDERSONE I., FAIX O. 2006: On the changes of pinewood (Pinus sylvestris L.) Chemical composition and ultrastructure during the attack by brown-rot fungi Postia placenta and Coniophora puteana. Int. Biodeterior. Biodegrad. 57(2); 99-106 7. JONES D., HOWARD N., SUTTIE E. 2011: The potential of propolis and other naturally occurring products for preventing biological decay. The International Research Group on Wood Protection, IRG/WP 11-30575 8. KĘDZIA B. 2006: Skład chemiczny i aktywność biologiczna propolisu pochodzącego z różnych rejonów świata. Post. Fitoter. 1; 23-35 9. KUJUMGIEV A., TSVETKOVA I., SERKEDJIEVA YU. BANKOVA V., CHRISTOV R., POPOV S. 1999: Antibacterial, antifungal and antiviral activity of propolis of different geographic origin. J. Ethnopharmacol. 64; 235-240 10. KUMAZAWA S., HAMASAKA T., NAKAYAMA T. 2004: Antioxidant activity of propolis of various geographic origins. Food Chem. 84; 329-339 11. MAHAMMADZADEH S., SHARIATPANAHI M., HAMEDI M., AHMADKHANIHA R., SAMADI N., OSTAD S.N. 2007: Chemical composition, oral toxicity and antimicrobial activity of Iranian propolis. Food Chem. 103; 1097-1103 12. MAI C., MILITZ H. 2004: Modification of wood with silicon compounds. Treatment systems based on organic silicon compounds – a review. Wood Sci. Technol. 37; 453-461 13. MELLIOU E., STRATIS E., CHINOU I. 2007: Volatile constituents of propolis from various regions of Greece - Antimicrobial activity. Food Chem. 103; 375-380 14. PANDEY K.K., PITMAN A.J. 2003: FTIR studies of the changes in wood chemistry following decay by brown-rot and white-rot fungi. Int Biodeterior Biodegrad 52; 151-160 15. TINGAUT P., WIEGENAND O., MAI C., MILLITZ H., SÈBE G. 2006: Chemical reaction of alkoxysilane molecules in wood modified with silanol groups. Holzforschung 60; 271-277 16. UZEL A., SORKUN K., ONCAG O., COGULU D., GENCAY O., SALIH B. 2005: Chemical composition and antimicrobial activities of four different Anatolian propolis samples. Microbiol. Res. 160; 189-195 17. WOŹNIAK M., RATAJCZAK I., SZENTNER K., KWAŚNIEWSKA P. MAZELA B. 2015: Propolis and oragnosilanes in wood protection. Part I: FTIR analysis and biological tests. Ann. WULS-SGGW, For and Wood Technol. 91; 218-224

Streszczenie: Badania nad wykorzystaniem propolisowo-silanowych preparatów impregnacyjnych w ochronie drewna – analizy chemiczne.Część I: analizy FTIR i EA. W pracy przedstawiono pierwszą część wyników badań chemicznych (FTIR i EA) drewna zabezpieczonego preparatem składającym się z ekstraktu propolisu i organosilanów (metylotrimetoksysilan i (3-(metakryloksy)propylo) trimetoksysilan). Porównywano wyniki badań chemicznych impregnowanego drewna, drewna po wymyciu a następnie po działaniu grzyba Coniophora puteana. Niewielkie różnice w wynikach azotu, węgla, wodoru i tlenu oznaczone w drewnie po impregnacji, po wymyciu oraz po działaniu C. puteana, potwierdzają trwały charakter wiązania preparatu z drewnem. Stabilny charakter wiązań Si-C i Si-O został wykazany w widmach IR. Wspomniane pasma charakterystyczne dla drgań wiązania krzemu z węglem i tlenem oznaczono zarówno w widmach drewna przed i po wymyciu w zakresie 830 i 765 cm-1. Ponadto w widmach tych próbek oznaczono pasma w zakresie 1720 i 1705 cm-1 charakterystyczne dla grup karbonylowych pochodzących z propolisu i MPTMOS. Ponadto, w artykule omówiono wyniki analizy strukturalnej drewna poddanego działaniu grzyba C. puteana. Ocena zmian w obrębie pasm 1375 i 1160 cm-1 może być zasadna przy określeniu odporności drewna na działanie grzybów.

Acknowledgement The study was supported by financial resources of the research project no 507.472.50.

Corresponding author:

Izabela Ratajczak Poznań University of Life Sciences, Department of Chemistry Wojska Polskiego 75, PL-60625 Poznań, Poland e-mail: [email protected]

37 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 38-42 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Investigation of the use of impregnating formulation with propolis extract and organosilanes in wood protection – chemical analyses. Part II: AAS, XRF and XRD analyses.

1RATAJCZAK IZABELA, 1WOŹNIAK MAGDALENA, 2MICHAŁ KRUEGER, 3SŁAWOMIR BORYSIAK

1Poznań University of Life Sciences, Department of Chemistry, Wojska Polskiego 75, PL-60625 Poznan, Poland 2Adam Mickiewicz University in Poznan, Institute of Prehistory, Umultowska 89D, PL-61614 Poznan, Poland 3Poznan University of Technology, Faculty of Chemical Technology, Berdychowo 4, PL-60965Poznan, Poland

Abstract: Investigation of the use of impregnating formulation with propolis extract and organosilanes in wood protection – chemical analyses. Part II: AAS, XRF and XRD analyses. The aim of this part of the study was to evaluate reactivity of wood and constituents of a formulation containing propolis extract and two organosilanes: methyltrimethoxysilane and (3-(trimethoxysilyl)propyl methacrylate). The paper presents silicon content on the surface and the entire volume of treated wood. Slight differences in silicon contents of unleached and leached treated wood suggest the stability of the silane bonds with wood and the hydrophobisation capacity of organosilanes, used as components of a protecting formulation applied on pine wood. Moreover, results of the degree of crystallinity confirmed hydrophobic properties of organosilanes and protective components of propolis before extraction.

Keywords: propolis, organosilanes, AAS, XRF, XRD

INTRODUCTION Traditional wood protection methods use chemicals that are often toxic and could have a negative influence both on human health and the environment. In recent years there has been an increasing interest in studies aimed at developing new wood preservatives based on natural substances and chemical compounds, harmless to people and the environment. Such substances as natural oils, proteins, silicon compounds, alkaloids or propolis can be used in wood protection [Jones et al. 2011, Kartal et al. 2009, Mazela et al. 2015, Ratajczak et al. 2004]. Silicon compounds are generally harmless to the environment and are highly promising substances for wood protection. Organosilanes increase resistance to biological attack and enhance hydrophobicity of modified wood. Numerous wood properties, such as weather resistance, strength, fire resistance and dimensional stability, are improved thanks to the application of organosilanes [Tingaut et al. 2006,Sebe, Brook 2001, Sebe, De Jeso 2000]. Propolis is a natural material, which has numerous applications, e.g. in food processing, cosmetics, pharmaceutical and optoelectronic industries as well as medicine [Castaldo, Capasso 2002, Drapak et al. 2006, Gong et al. 2012, Kartal et al. 2003]. Extracts of propolis were also used as components in wood protecting formulations [Budija et al. 2008, Jones et al. 2011]. Propolis extracts possess antibacterial, antifungal, anticancer, anti-inflammatory, hepatoprotective and antiviral properties [Kartal et al. 2003, Mavri et al. 2012, Uzel et al. 2005]. This bee product has a highly complex composition. It usually contains phenols (including flavonoids, phenolic acids and their esters), vitamins, sugars, fatty acids and chemical elements [Castaldo, Capasso 2002, Gong et al. 2012, Mahammadzadeh et al. 2007, Uzel et al. 2005]. The aim of this paper was to evaluate reactivity of organosilanes and wood treated with a formulation consisting of propolis extract and two organoislanes: methyltrimethoxysilane (MTMOS) and (3-(trimethoxysilyl)propyl methacrylate) (MPTMOS).

38 MATERIALS AND METHODS Chemicals The formulation used in this study consisted of 15% ethanolic propolis extract, and two organosilanes: methyltrimethoxysilane (MTMOS) CH3Si(OCH3)3 (Siltec, Poland) and (3- (trimethoxysilyl)propyl methacrylate) (MPTMOS) H2C=C(CH3)CO2(CH2)3Si(OCH3)3 (Sigma Aldrich, Germany) at a 5% concentration. Wood material Wood samples used in this study were Scots pine sapwood treated with examined formulation and leached according to standard EN 84. X-ray fluorescence (XRF) Wood samples of 40×15×5 mm (the last dimension along the grain) were used in this study. Surfaces of impregnated wood were analysed using portable X-ray fluorescence spectrometer Bruker Tracer III-SD (Bruker, USA). Each sample was scanned in five points using a collimator with a 5x5 mm screen. The time of one measurement was 30 s. Quantitative values of silicon on treated wood surfaces were determined using the MajMudRock calibration method, as calibration for a wooden matrix is not available. Atomic absorption spectrometry (AAS) Wood samples were homogenised with a ball mill (Ika, Germany) and the powdered homogenous material was used for analyses. Representative 0.5000 g wood samples were mineralised with nitric acid (Sigma-Aldrich, Germany) in the microwave mineralization system (CEM Corporation, USA) and after cooling down the digested solutions were filtered and diluted to 50.0 ml with deionized water using the Milli-Q system (Merck Millipore, USA). The procedure were performed with tree replications for all samples. The content of Si in wood samples was determined by flame atomic absorption spectrometry (FAAS) using a Duo AA280FS/AA280Z spectrometer (Agilent Technologies, Australia). The calibration curve was prepared on the basis of a series of the freshly prepared standard obtained from the standard solution of analysed elements with 5 replicates. The average of the three replicates was calculated. X-ray powder diffraction (XRD) The supermolecular structure of wood was analyzed by means of wide angle X-ray scattering. The diffraction pattern was recorded between 5 and 30 o (2θ-angle range) in the step of 0.04o/3 sec. The wavelength of the Cu Kα radiation source was 1.5418 Å, and the spectra were obtained at 30 mA with an accelerating voltage of 40 kV. Deconvolution of peaks was performed by the method proposed by Hindeleh and Johnson [1971], improved and programmed by Rabiej [1991]. After separation of X-ray diffraction lines, the degree of crystallinity (Xc) by comparison of areas under crystalline peaks and amorphous curve was determined. The changes in the supermolecular structure of wood were analyzed in a function of chemical modification process.

RESULTS AND DISCUSSION Table 1 presents silicon concentrations on the surface of Scots pine wood impregnated with a formulation containing propolis extract and organosilanes: methyltrimethoxysilane and (3-(trimethoxysilyl)propyl methacrylate),analysed using X-ray fluorescence spectroscopy. The silicon content of leached wood was slightly lower than in the case of unleached wood.

39 Table 1. Silicon contents on the surface and the entire volume of treated wood. X-ray fluorescence spectroscopy (XRF) Sample Silicon content [ppm] Unleached wood 9.35 ± 0.23 Leached wood 8.39 ± 0.22 Atomic absorption spectrometry (AAS) Sample Silicon content [mg/kg] Unleached wood 520.25 ± 4.88 Leached wood 479.00 ± 5.23

The concentration of Si in the entire volume of treated wood was analysed using atomic absorption spectrometry and it was very similar for unleached and leached wood samples. The results of atomic absorption spectrometry analysis are shown in Table 1. The Si content slightly decreased in wood samples after leaching and it was 479.00 ± 5.23 mg/kg in comparison to that of unleached wood, which was 520.25 ± 4.88 mg/kg. These results can suggest stability of silane bonds with wood and the hydrophobisation capacity of organosilanes, used as components of the protecting formulation applied on the pine wood.

Table 2. The degree of crystallinity in untreated and treated wood Sample The degree of crystallinity [%] 50 Untreated wood EN 84 55

53 Treated wood EN 84 53 EN 84 – wood after leaching procedure, according to EN 84 standard The results of X-ray powder diffraction analyses for the degree of crystallinity of untreated and treated wood are presented in Table 2. The degree of crystallinity of untreated wood before and after extraction was 50 and 55%, respectively, while the degree of treated unleached and leached wood was 53%. Differences in the degree of crystallinity in untreated wood (before and after extraction) is caused the extraction of amorphous low molecular compounds from wood. However, the same degree of crystallinity of treated wood before and after leaching was observed. A slight decrease in the degree of crystallinity compared to the untreated wood (after leaching), can be explained by the course of chemical treatment. Probably, hydrophobization of wood surface is responsible for the decrease in crystallinity content due to the steric barriers.

CONCLUSIONS All the parts of the study present the results of biological and chemical analyses of wood treated with a protecting formulation containing propolis extract and organosilanes: (methyltrimethoxysilane and (trimethoxysilyl)propyl methacrylate). Treated wood also after the leaching procedure (EN 84) exhibited resistance to C. puteana and was classified as durability class 1 (“very durable”) according to the EN 350 standard. Ergosterol contents, presented in terms of ERG reduction, in treated wood samples after exposure to the analysed fungus confirmed fungistatic properties of the tested formulation. Results of chemical analyses confirmed durability of chemical bonds between wood and formulation constituents. Slight differences in silicon contents between unleached and leached treated wood analysed using atomic absorption spectrometry (AAS) and X-ray fluorescence spectroscopy (XRF) suggest hydrophobisation capacity of organosilanes, used as components of the protecting formulation applied on wood. Moreover, the results showing the degree of crystallinity confirmed hydrophobic properties of organosilanes and protect the components of propolis

40 before extraction. The propolis and silane formulation proved to be an effective constituent of biocide-free and bio-friendly preservatives for wood protection.

REFERENCES 1. BUDIJA F., HUMAR M., PETRIC M. 2008: Propolis for wood finishing. The International Research Group on Wood Protection IRG/WP 08-30464 2. CASTALDO S., CAPASSO F. 2002: Propolis, an old remedy used in modern medicine. Fitoterapia 73(1); S1-S6 3. DRAPAK S.I., BAKHTINOV A.P., GAVRYLYUK S.V., DRAPAK I.T., KOVALYUK Z.D. 2006: Structural and optical characterization of the propolis films. Appl. Surf. Sci. 253; 279-282 4. GONG S., LUO L., GONG W., GAO Y., XIE M. 2012: Multivariate analyses of element concentrations revealed the groupings of propolis from different regions in China. Food Chem. 134; 583-588 5. HINDELEH A.M., JOHNSON D.J. 1971: The resolution of multipeak data in fibre science. J Phys. Appl Phys. 4; 259-63 6. JONES D., HOWARD N., SUTTIE E. 2011: The potential of propolis and other naturally occurring products for preventing biological decay. The International Research Group on Wood Protection, IRG/WP 11-30575 7. KARTAL M., YILDIZ S., KAYA S., KURUCU S., TOPCU G. 2003: Antimicrobial activity of propolis samples from two different regions of Anatolia. J. Ethnopharmacol 86; 69-73 8. KARTAL S.N. YOSHIMURA T., IMAMURA Y. 2009: Modification of wood with Si compounds to limit born leaching from treated wood and to increase termite and decay resistance. Int. Biodeter. Biodegr. 63; 187-190 9. MAHAMMADZADEH S., SHARIATPANAHI M., HAMEDI M., AHMADKHANIHA R., SAMADI N., OSTAD S.N. 2007: Chemical composition, oral toxicity and antimicrobial activity of Iranian propolis. Food Chem. 103; 1097-1103 10. MAVRI A., ABRAMOVIC H., POLAK T., BERTONCELJ J., JAMNIK P., MOZINA S.S., JESEK B. 2012: Chemical properties and antioxidant and antimicrobial activities of Slovenian propolis. Chem. Biodivers. 9; 1545-1556 11. MAZELA B., BRODA M., PERDOCH W., GOBAKKEN L.G., RATAJCZAK I., COFTA G., GRZEŚKOWIAK W., KOMASA A., PRZYBYŁ A. 2015: Bio-friendly preservative systems for enhanced wood durability – the first periodic raport on DURAWOOD project. The International Research Group on Wood Protection. IRG/WP 15-30677 12. RABIEJ S. 1991: A comparison of two X-ray diffraction procedures for crystallinity determination. Eur Polym J. 27; 947-54 13. RATAJCZAK. I., HOFFMANN S.K. GOSLAR J. MAZELA B. 2004: Fixation of copper(II)-protein formulation in wood: Part I. Influence of tannic acid on fixation of copper in wood. Holzforschung 62(3); 294-299 14. SEBE G. BROOK M.A. 2001: Hydrophobization of wood surfaces: covalent grafting of silicone polymers. Wood Sci. Technol. 35; 269-282

41 15. SEBE G. DE JESO B. 2000: The dimensional stabilisation of maritime pine sapwood (Pinus pinaster) by chemical reaction with organosilicon compounds. Holzforschung 54; 474-480 16. TINGAUT P., WIEGENAND O., MAI C., MILLITZ H., SÈBE G. 2006: Chemical reaction of alkoxysilane molecules in wood modified with silanol groups. Holzforschung 60; 271-277 17. UZEL A., SORKUN K., ONCAG O., COGULU D., GENCAY O., SALIH B. 2005: Chemical composition and antimicrobial activities of four different Anatolian propolis samples. Microbiol. Res. 160; 189-195

Streszczenie: Badania nad wykorzystaniem propolisowo-silanowych preparatów impregnacyjnych w ochronie drewna – analizy chemiczne. Część II: analizy AAS, XRF i XRD. W pracy zbadano możliwość oddziaływania drewna sosny zwyczajnej z preparatem, w skład którego wchodzą: ekstrakt propolisu i dwa związki krzemoorganiczne: metylotrimetoksysilan i (3-(metakryloksy)propylo)trimetoksysilan. W próbkach zabezpieczonego drewna, poddanego również przyspieszonemu starzeniu według normy EN 84 (procedura wymywania) oznaczono stężenie krzemu – na powierzchni zabezpieczonego drewna wykorzystują spektroskopię fluorescencji rentgenowskiej (XRF) oraz w całej objętości próbki za pomocą atomowej spektroskopii absorpcyjnej (AAS). Niewielkie różnice w zawartości krzemu w próbkach niewymywanych oraz wymywanych mogą wskazywać na hydrofobowe właściwości wykorzystanych organosilanów. Ponadto, dla próbek zabezpieczonego drewna przed i po wymywaniu otrzymano te same wartości stopnia krystaliczności, co dodatkowo potwierdza charakter hydrofobowy silanów oraz wskazuje na zabezpieczenie składników propolisu przed wymyciem. Acknowledgement The study was supported by financial resources of the research project no 507.472.50 and DEC-2013/09/B/HS3/00630.

Corresponding author:

Izabela Ratajczak Poznań University of Life Sciences, Department of Chemistry Wojska Polskiego 75, PL-60625 Poznań, Poland e-mail: [email protected]

42 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 43-47 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Investigation of the use of impregnating formulation with propolis extract and organosilanes in wood protection – biological analyses.

1WOŹNIAK MAGDALENA, 1RATAJCZAK IZABELA, 1AGNIESZKA WAŚKIEWICZ, 1KINGA SZENTNER, 2GRZEGORZ COFTA, 2PATRYCJA KWAŚNIEWSKA-SIP

Abstract: Investigation of the use of impregnating formulation with propolis extract and organosilanes in wood protection – biological analyses. The paper presents results of mycological tests of wood treated with a protecting formulation based on propolis extract and silanes (methyltrimethoxysilane and (trimethoxysilyl)propyl methacrylate). Treated wood exposed to C. puteana exhibited resistance to the examined fungus and was classified as durability class 1 (“very durable”), according to the EN 350 standard. Fungistatic properties were also observed when treated wood was leached, according to the EN 84 standard and after exposure to the fungus. Results of the ergosterol assay, in the form of ERG reduction, in treated wood samples after exposure to C. puteana also confirmed fungistatic properties of the tested formulation. The formulation containing propolis extract and silane proved to be an effective constituent of biocide-free wood preservatives.

Keywords: propolis, organosilanes, Coniophora puteana, ergosterol, HPLC

INTRODUCTION Propolis, or bee glue, is a brownish, resinous material collected by honeybees from leaves of numerous tree species and exudates from wounds in plants. The term propolis derives from two Greek words: pro (“in front of”, “at the entrance”) and polis (“city”, “community”) and means a substance used in defence of the hive [Castaldo and Capasso 2002]. Bees apply propolis as a building material and also to ensure low concentrations of fungi and bacteria inside the hives. Extracts of propolis possess various biological activities, such as antifungal, antibacterial, antiviral, anticancer and antioxidant [Ahn et al. 2007, Banskota et al. 2001, Popova et al. 2005]. The antibacterial and antifungal properties are the most investigated and the most popular biological activities of this bee product. Numerous literature data show that extracts of propolis coming from different regions inhibit growth of various species of fungi including Candida albicans, C. parapsilosis, Aspergillus niger, A. flavus and Colletotrichum gloeosporioides [Aguero et al. 2011, Kacaniova et al. 2012, Koc et al. 2007, Meneses et al. 2009]. Moreover, the preliminary research indicates that Scots pine wood samples treated with propolis extract showed resistance against wood destroying fungi, such as Coniophora puteana and Trametes versicolor [Budija et al. 2008, Jones et al. 2011]. Silicon compounds exhibit hydrophobic properties provided by the presence of organic groups. This group of chemical compounds is used in different branches of industry, such as pulp and paper, building, textile industries as well as wood protection. Organosilanes are used in order to increase hydrophobicity, fire resistance, dimensional stability or antifungal properties of treated wood [Mai and Militz 2004, Sebe and Brook, 2001, Tingaut et al. 2006]. The aim of the following study was to determine potential antifungal properties of wood treated with a formulation consisting of propolis extract and organosilanes.

43 MATERIALS AND METHODS

Chemicals The formulation used in this study consisted of 15% ethanolic propolis extract, and two organosilanes: methyltrimethoxysilane (MTMOS) CH3Si(OCH3)3 (Siltec, Poland) and (3- (trimethoxysilyl)propyl methacrylate) (MPTMOS) H2C=C(CH3)CO2(CH2)3Si(OCH3)3 (Sigma Aldrich, Germany) at a 5% concentration. The ethanolic propolis extract was supplied by PROP-MAD (Poland).

Wood material and impregnation Scots pine (Pinus sylvestris L.) sapwood samples of 40×15×5 mm (the last dimension along the grain) were used in this study. The average density of wood samples was 540 kg/m3. The samples were treated with impregnating formulations using the vacuum method – 15 minutes under vacuum conditions – 1MPa and 2 hours under atmospheric pressure. Half of the treated samples were subjected to an accelerated leaching procedure according to the EN 84 standard.

Biological tests Prepared wood samples were exposed to the brown rot fungus Coniophora puteana (Schumacher ex Fries) Karsten (BAM Ebw. 15), according to the modified EN 113 standard. Weight loss and moisture content of wood samples were determined after 8 weeks of exposure. Wood resistance to fungi was assessed according to the standard concerning classification of natural durability of wood (according to the EN 350 standard), by calculating the ratio (x = Ut/Uk) of average corrected mass loss of treated wood samples (Ut) to average mass loss of control samples (Uk). Treated wood was classified as: “very durable”, “durable”, “moderately durable”, “slightly durable” and “not durable” (EN 350).

Ergosterol (ERG) analysis Samples of 0.1 g ground wood were extracted with 2 ml methanol and 0.5 ml 2M aqueous sodium hydroxide. Samples were irradiated thrice in a microwave oven and after cooling were neutralized with 1 ml of 1M aqueous hydrochloric acid. Thereafter, the samples were subjected to pentane extraction of ergosterol. After evaporation of the solvent the samples were stored at -30°C until chromatographic analysis. Ergosterol was separated on a 3.9 x 150 mm Nova Pak C-18, 4 µm column with the methanol: acetonitrile mixture (90:10, v/v) as a mobile phase. EGR was detected with the Waters 2996 Photodiode Array Detector (Waters Division of Millipore, USA) set at 282 nm. The presence of ergosterol was confirmed by a comparison of retention time with the external standard and by co-injection of every tenth sample with an ERG standard.

RESULTS AND DISCUSSION The results of the biological degradation test caused by C. puteana of Scots pine wood samples treated with the formulation based on the propolis extract and silanes (MPTMOS and MTMOS) are presented in Table 1. Average mass loss of control samples was greater than 30%, which suggests that the decay activity of C. puteana toward non-impregnated Scots pine sapwood was in line with the guidelines of the standard (EN 113). The mass loss of unleached wood was 3.8% and according to the EN 350 standard treated wood can be classified as durability class 1 (“very durable”). Fungistatic properties were also observed when treated wood samples were leached and exposed to the investigated fungus. Leached wood showed a 3.0% mass loss and it was classified as durability class 1.

44 Table 1. The mass loss, wood moisture content and retention of treated wood Retention WMC Sample RSD RSD WL [%] RSD DC [kg/m3] [%] TS 162.56 2.89 44.0 4.5 3.8 0.1 Unleached treated wood 1 CS - - 80.1 7.7 32.3 3.6 TS 166.19 4.90 35.4 3.2 3.0 0.3 Leached treated wood 1 CS - - 79.6 7.2 34.7 5.1 TS – tested sample, CS – control sample, RSD – relative standard deviation, WMC – wood moisture content, WL – weight loss, DC – durability class acc. to the EN 350 standard

The Scots pine wood impregnated with the examined formulation after leaching was more effectively protected than unleached wood. Probably the reason for this phenomenon may be connected with hydrolysis of silanes in the presence of water during the leaching procedure and the increase in hydrophobic properties of treated wood.

Table 2. Ergosterol content in treated wood samples after exposure to C. puteana Ergosterol content Ergosterol Sample RSD [µg/g] reduction [%] TS 9.26 0.32 Unleached treated wood 24.65 CS 12.29 0.53 TS 7.58 0.75 Leached treated wood 37.86 CS 12.15 0.20 TS – tested sample, CS – control sample,RSD – relative standard deviation

Ergosterol analysis is another technique that may be used to detect decay fungi in wood [Eikenes et al. 2005, Pilgard et al. 2009]. Results of the ergosterol assay are presented in Table 2. The examined sterol content in unleached treated wood samples was 9.26 µg/g and in wood after leaching – 7.58 µg/g. Ergosterol reduction confirmed the effectiveness of the propolis and silane formulation on the inhibition of decay fungi in Scots pine wood samples. Higher ERG reduction levels in leached treated wood indicate better fungistatic properties of wood after water leaching than those of wood before the ageing procedure.

CONCLUSIONS The results of the mycological test showed that the wood protective formulation consisting of the propolis extract and organosilanes (MPTMOS and MTMOS) exhibited fungistatic properties. Pine wood treated with the above-mentioned formulation exposed to C. puteana exhibited resistance to the tested fungus. Wood samples impregnated with the propolis and silane formulation had index 1 (“very durable”) in comparison to natural Scots pine sapwood, which is classified as class 5 (“not durable”) as regards its resistance to Basidiomycotina fungi, according to the EN 350 standard. The results of the ergosterol assay, presented in terms of ERG reduction, also confirm fungistatic properties of the tested formulation. The propolis and silane formulation proved to be an effective constituent of biocide-free and bio-friendly preservatives for wood preservation.

REFERENCES 1. AGUERO M.B. SVETAZ L., SANCHEZ M., LUNA L., LIMA B., LOPEZ M.L., ZACCHINO S., PALERMO J., WUNDERLIN D., FERESIN G.E., TAPIA A. 2011: Argentinean Andean propolis associated with the medicinal plant Larreanitida Cav. (Zygophyllaceae). HPLC-MS and GC-MS characterization and antifungal activity. Food Chem. Toxicol. 49; 1970-1978

45 2. AHN M.R., KUMAZAWA S., USUI Y., NAKAMURA J., MATSUKA M., ZHU F., NAKAYAMA T. 2007: Antioxidant activity and constituents of propolis collected in various areas of China. Food Chem. 101; 1383-1392 3. BANSKOTA A.H., TEZUKA Y., KADOTA S. 2001: Recent progress in pharmacological research of propolis. Phytother. Res. 15; 561-571 4. BUDIJA F., HUMAR M., KRICEJ B., PETRIC M. 2008: Propolis for wood finishing. The International Research Group on Wood Protection, IRG/WP 08-30464 5. CASTALDO S., CAPASSO F. 2002: Propolis, an old remedy used in modern medicine. Fitoterapia 73(1); S1-S6 6. EIKENES M., HIETALA A.M., ALFREDSEN G., FOSSDAL C.G, SOLHEIM H. 2005: Comparision of quantitative real-time PCR, chitin and ergosterol assays for monitoring colonization of Trametes versicolor in birch wood. Holzforschung 59; 568-573 7. JONES D., HOWARD N., SUTTIE E. 2011: The potential of propolis and other naturally occurring products for preventing biological decay. The International Research Group on Wood Protection, IRG/WP 11-30575 8. KACANIOVA M., VUKOVIC N., CHLEBO R., HASCIK P., ROVNA K., CUBON J., DZUGAN M., PASTERNAKIEWICZ A. 2012: The antimicrobial activity of honey, bee pollen loads and beeswax. Arch. Biol. Sci. 64(3); 927-934 9. KOC A.N., SILICI S., MUTLU-SARIGUZEL F., SAGDIC O. 2007: Antifungal activity of propolis in four different fruit juices. Food Technol. Biotechnol. 45(1); 57-61 10. MAI C., MILITZ H. 2004: Modification of wood with silicon compounds. Treatment systems based on organic silicon compounds – a review. Wood Sci. Technol. 37; 453-461 11. MENESES E.A., DURANGO D.I., GARCIA C.M. 2009: Antifungal activity against postharvest fungi by extracts from Colombian propolis. Quim Nova 32(8); 2011-2017 12. PILGARD A., ALFREDSEN G., BORJA I., BJORDAL C. 2009: Durability and fungal colonisation patterns in wood samples after six years in soil contact evaluated with qPCR, microscopy, TGA, chitin- and ergosterol assays. The International Research Group on Wood Protection, IRG/WP 09-20402 13. POPOVA M., SILICI S., KAFTANOGLU O., BANKOVA V. 2005: Antibacterial activity of Turkish propolis and its qualitative and quantitative chemical composition. Phytomedicine 12; 221-228 14. SÈBE G., BROOK M.A., 2001: Hydrophobization of wood surfaces: covalent grafting of silicone polymers, Wood Sci. Tech. 35; 269-282 15. TINGAUT P., WIEGENAND O., MAI C., MILLITZ H., SÈBE G. 2006: Chemical reaction of alkoxysilane molecules in wood modified with silanol groups. Holzforschung 60; 271- 277

Streszczenie: Badania nad wykorzystaniem propolisowo-silanowych preparatów impregnacyjnych w ochronie drewna – test biologiczny. W pracy przedstawiono wyniki badań mykologicznych drewna zabezpieczonego preparatem składającym się z ekstraktu propolisu i organosilanów (metylotrimetoksysilan i (3-(metakryloksy)propylo) trimetoksysilan). Zabezpieczone drewno wykazywało odporność względem grzyba C. puteana i charakteryzowało się 1 klasą odporności ("bardzo trwały"), według normy EN 350. Właściwości fungistatyczne były również obserwowane w przypadku zabezpieczonego drewna po przyspieszonych testach starzeniowych (według normy EN 84) i ekspozycji na działanie grzyba testowego. Wyniki zawartości ergosterolu w próbkach drewna po działaniu grzyba testowego, przedstawione w formie redukcji ergosterolu, potwierdziły przeciwgrzybiczne właściwości opracowanego preparatu. Otrzymane wyniki badań, wskazują na możliwość zastosowania badanego preparatu jako efektywnego składnika bezbiocydowych środków ochronnych do drewna.

Acknowledgement The study was supported by financial resources of the research project no 507.472.50. We would like to thank Danuta Madajczyk (PROP-MAD from Poznań, Poland), who supplied us the ethanolic propolis extract.

Corresponding author:

Izabela Ratajczak Poznań University of Life Sciences, Department of Chemistry Wojska Polskiego 75, PL-60625 Poznań, Poland e-mail: [email protected]

47 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 48-54 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Comparison of susceptibility of European aspen (Populus tremula L.) and oak (Quercus sp.) against molds Aspergillus niger (Tiegh) and Chaetomium globosum ((Kunze)Fr.).

BARTŁOMIEJ RĘBKOWSKI, KRZYSZTOF J. KRAJEWSKI, AGNIESZKA MIELNIK Department of Wood Science and Wood Preservation, Faculty of Wood Technology, Warsaw University of Life Sciences - SGGW, 166 Nowoursynowska St., 02-787 Warsaw

Abstract: Comparison of susceptibility of European aspen (Populus tremula L.) and oak (Quercus sp.) against molds Aspergillus niger (Tiegh) and Chaetomium globosum ((Kunze)Fr.).

In the conditions of high moisture wood is exposed to molds, which not only influences on wood appearance, but also are dangerous to human life. European aspen wood (Populus tremula L.) is traditionally used for roofing and fence building. It also finds more and more uses both indoor and outdoor, where it can be exposed to molds. Comparison of susceptibility towards growth mold Aspergillus niger (Tiegh) and Chaetomium globosum ((Kunze)Fr.) between aspen wood and oak sapwood (Quercus sp.) have been made. The result of this research showed, that aspen wood is less susceptible toward growth of Aspergillus than oak sapwood. The susceptibility of aspen wood towards development of Chaetomium is comparable to oak, although slightly lower rate of mycelium growth has been observed. This result may be explained by the fact, that trembling aspen wood contains less nonstructural components than oak, therefore the environment for mold growth on aspen is less fertile.

Keywords: European aspen, aspen,, oak, mold, Aspergillus niger, Chaetomium globosum

INTRODUCTION Molds commonly exists in buildings. They grow on all kinds of materials, such as wood, wood-based materials, plasters, walls, paints or plastics. For their growth they need high humidity in the air and material. They also need some quantity of organic matter. It may be a drop of juice or fats and proteins form our touch. Other source of nutrients are the material itself, for example wood and its non-structural components (Zyska 1999, Ważny, Karyś 2001, Papciak, Zamorska 2007, Żukiewicz-Sobczak et al. 2012). Presence of mold is not only a threat of slight material bio deterioration, but, most of all, a great threat for human health and even life. Bio corrosive effect of mold growth towards organic materials is caused by its enzymes. The non-organic materials are damaged by secreted by mold organic acids (Zyska 1999). Mold can cause air-transmitted diseases, allergies, tineas or mycotoxicosis. Considered as the most dangerous kind of all molds are: Candida, Cladosporium, Mucor, Penicillium, Rhizopus, Altrnaria, Aspergillus, Stemphyllium, Botrytis, Chaetomium (Papaciak, Zamorska 2007, Wołejko, Matejczyk 2011). Gutarowska (2010) showed, that in laboratory conditions, materials containing proteins and cellulose, kept in the high humidity conditions promotes not only growth of mold mycelium, but also secretion of allergens and mitotoxins. Aspergillus genus contains about 150 species of molds, growing on highly moisten materials, such as wood, walls or paints (Ważny, Karyś 2001). It is one of the most common mold in the buildings. Reinprecht (2012) mentions it as one of the most frequent species to be found on wood and wood-based materials. It also has been showed that the 35 % of all found species in the air at sewer treatment plant were form Aspergillus genus (Cyprowski et al. 2008). Chaetomium globosum develops on highly moisten wood, wood-based materials and other kinds of building material. This mold can cause bio-deterioration of wood on depth of 1

48 – 2 mm. It may also cause grey rot when wood moisture is high (Ważny, Karyś 2001). It is considered as one of the most important mold that destroys interiors (Papciak, Zamorska 2007). Because molds are great threat for human health and life, it is most important to test building and decorative materials for their resistance to it. Both Aspergillus niger (Tiegh.) and Chaetomium globosum ((Kunze)Fr.) are one of the most important species used for indication of wood bio resistance towards molds (Instruction ITB no. 355/98). Aspen wood (Populus tremula L.) has increasing importance in forestry and wood industry because of its fast growing and its ability to grow on poor soils or industry polluted grounds. It is considered as pioneer species. Traditionally aspen is used for roofing and fence building. It is widely used in match making and cellulose making (Seneta 2000). It is also one of the main woods used for production of transport palettes. At present new uses for this wood are being searched such as floorings production (base in multi-layer floorings) or construction wood production. According to norm PN-EN 350-2: Natural durability of solid wood, aspen wood is considered as non-durable (durability class 5), oak wood is considered as durable to mediocre durable (durability class 2-3). Natural durability is dependent on wood species, age, density and kind of wood (heartwood / sapwood). Aspen is considered as non-heartwood species (Kokociński 2005). Some authors, among others Borrega et al. (2009) and Johansson, Kieftew (2010), refers in their works to aspen heartwood.

MATERIALS AND METHODS The research have been performed on aspen – European aspen (Populus tremula L.) and oak (Quercus sp.) wood samples. Aspen wood is considered as non-durable (class 5 of wood durability against fungi according PN-EN 350-2), oak wood is considered as durable to mediocre durable (class 2 – 3 of wood durability against fungi according to PN-EN 350-2) Aspen wood samples have been cut from near the bark area. Oak wood samples have been cut from sapwood. Diameters of both kinds of samples were the same: 40 x 25 x 4 mm (longitudinally, radially, tangentially). All equipment (glass, petri dish, tweezers etc.), wood samples and growth medium have been sterilized in high temperature and steam. Procedure have been performed twice, both times in temperature of 80 oC for period of 24 hours. For the research agar only growth medium have been chosen. It has been assumed that growth medium should only give moisture and support samples during research period, and should be as least fertile as possible. Growth medium was 0,75 % agar solution in water. This was the lowest concentration of agar that supported sample on the surface of growth medium after its solidification. Two species of mold have been used in the research: Aspergillus niger (Tiegh) and Chaetomium globosum ((Kunze)Fr.). Both molds have been inoculated on 6 samples of each species of wood. Wood samples have been placed in petri glass (No. 9), directly on growth medium, two pieces in each. (Fig. 1). For the research 24 samples of wood have been used total. All prepared petri glass with wood samples have been placed in incubator for two weeks, temperature set was 27,8 oC. Additionally two petri glass with growth medium only, inoculated with molds, have been placed as reference samples in incubator.

49 Table 1. Quantities of samples in each test series. Mold Species European aspen samples Oak samples (pcs) (pcs) Aspergillus niger 6 6 Chaetomium globosum 6 6

Figure 1. Prepared petri glass with oak samples (authors)

The susceptibility of European aspen wood and oak sapwood have been assessed on the basis of growth rate of mold on samples. Four parameters have been used for the assessment: rate of mycelium growth separately for wood sample surface and for free growth medium surface, rate of conidia growth separately for wood sample surface and for free growth medium surface. Test results have been gathered on 1, 2, 3, 5, 6, 11 and 14th day of growth. The results gathered after each period of time are the coverage of surface by mycelium or conidia. The ratio of covered surface have been compared to whole surface of wood sample or growth medium.

RESULTS Aspen wood showed lower susceptibility towards growth of Aspergillus niger than oak sapwood in all four aspects of assessment. Growth of Aspergillus mycelium on samples surface on both kind of wood reached 100 % within full duration of test (oak – day 5, aspen day 6), although mold development on aspen samples begin later. It also reached maximum coverage a day later and showed lower dynamics of growth. The development of conidia on aspen samples surface were lower than on oak sapwood. Growth rate of both, mycelium and conidia, on free surface of growth medium were lower for aspen samples and the results were accordingly 71,8 % and 47,3 %, while result for oak sapwood were 100 % in both aspects. Detailed test results have been shown on Figure 2..

50 A1. A2.

A3. A4.

Figure 2. Comparison of growth rate of Aspergillus niger on oak and aspen. Coverage ratio development during 14 days of test: A1- mycelium on sample surface, A2 – mycelium on growth medium free surface, A3 – conidia on sample surface, A4 – conidia on growth medium free surface.

1. 2.

Figure 3. Results of growth of Aspergillus niger on aspen (1.) and oak (2.)

Susceptibility of aspen towards Chaetomium was comparable to oak sapwood. The growth rate of mycelium on samples surfaces were higher for oak. Like in Aspergillus growth test, the mycelium begin development later on aspen and the dynamics of growth was lower. Coverage on both kinds of wood during the test reached 100 % (oak – day 11, aspen – day 14). The growth dynamics of mycelium on growth medium free surface were higher for aspen samples until day 7. After that day mycelium development on aspen slowed and coverage reached 69,3 %, while coverage on oak reached 92,4 %. Coverage of conidia on aspen samples surface were higher and reached 47,9 %, while on oak samples it was 15,6 %. The growth of conidia on growth medium free surface were comparable for both molds and the coverage reached about 20 %.

51 B1. B2.

B3. B4.

Figure 4. Comparison of growth rate of Chaetomium globosum on oak and aspen. Coverage ratio development during 14 days of test: B1- mycelium on sample surface, B2 – mycelium on growth medium free surface, B3 – conidia on sample surface, B4 – conidia on growth medium free surface.

1. 2.

Figure 5. Results of growth of Chaetomium globosum on aspen (1.) and oak (2.)

There were no growth of Aspergillus and Chaetomium observed on reference samples.

CONCLUSIONS The aspen wood showed grater susceptibility towards Aspergillus niger development than oak sapwood in all four assessed aspects: mycelium and conidia growth on sample surface and growth medium free surface. It also showed greater susceptibility toward development of Chaetomium globosum mycelium, although it showed greater coverage of conidia on samples surface. This conclusions stands in contrary to common opinion, that aspen wood is more susceptible towards bio deterioration than oak. Interesting aspect of this research is that growth rate of both molds mycelium on growth medium free surface was much lower for samples of aspen wood. Because for the research was used special growth medium poor in nutrients it may indicate that either or both transition of nutrients into growth medium form aspen wood was lower than from oak

52 sapwood (aspen contains fewer non-structural components such as sugars, fats or protein) or the aspen wood contains inhibitors of growth for molds (although the oak wood is the one that contains tannins). This aspect will be subjected to further study.

REFERENCES 1. BORREGA M., NEVALAINEN S.,, HERAJARVI H., 2009: Resistance of European and hybrid aspen wood against two brown rot fungi. European Journal of Wood Products, 67: 177 – 182. 2. CYPROWSKI M., SOWIAK M., SOROKA P. M., BUCZYŃSKA A., KOZAJDA A., SZADKOWSKA-STAŃCZYK I., 2008: Ocena zawodowej ekspozycji na aerozole grzybowe w oczyszczalni ścieków. Medycyna pracy 59: 365 – 371. 3. FLAETE P.O., HOIBO O. A., FJAERTOFT F., NILSEN T. –N., 2000: Crack formation in unfinished siding of aspen (Populus tremula) and Norway spruce (Picea abies) during accelerated weathering. Holz als Roh- und Werkstoff, 58: 135 – 139. 4. GUTAROWSKA B., 2010: Grzyby strzępkowe zasiedlające materiały budowlane. Wzrost oraz produkcja mitotoksyn i alergenów. Zeszyty Naukowe Politechniki Łódzkiej, Nr 1074. 5. JASIŃSKA B., 2002: Metody oceny skażenia obiektów budowlanych grzybami pleśniowymi. Foundations of civil and environmental engineering, No 3: 48 – 64. 6. KOKOCIŃSKI W., 2005: Anatomia drewna. Poznań. 7. PAPCIAK D., ZAMORSKA J., 2007: Korozja mikrobiologiczna w budynkach powodowana przez grzyby. Zeszyty Naukowe Politechniki Rzeszowksiej, Nr 246, Budownictwo i Inżynieria Środowiska, z. 46: 87 – 98. 8. REINPRECHT L., 2012: Ochrana dreva. Technicka univerzita vo Zvolene. 9. SENETA W., DOLATOWSKI J., 2000: Dendrologia. PWN. Warszawa. 10. WAŻNY J., KARYŚ J., pod red., 2001: Ochrona budynków przed korozją biologiczną. Arkady. Warszawa. 11. WOŁEJKO E., MATEJCZYK M., 2011: Problem korozji biologicznej w budownictwie. Budownictwo i inżynieria środowiska, 2: 191 – 195. 12. ZYSKA B., 1999: Zagrożenia biologiczne w budynku. Arkady. Warszawa. 13. PN-EN 350-2: Naturalna trwałość drewna litego. 14. INSTRUKCJA ITB: 355/98: Ochrona drewna budowlanego przed korozją biologiczną, środkami chemicznymi, wymagania i badania.

Streszczenie: Porównanie podatności drewna Topoli osiki (Populus tremula L.) oraz dębu (Quercus sp). na działanie grzybów pleśniowych Aspergillus niger (Tiegh) i Chaetomium globosum ((Kunze)Fr.).

W warunkach wysokiej wilgotności drewno narażone jest na infekcje spowodawne przez grzyby pleśniowe, które nie tylko wpływają na wygląd drewna, ale są też niezdrowe dla człowieka. Drewno topoli osiki (Populus tremula L.) jest tradycyjnie stosowane na pokrycia dachowe oraz gorodzenia, znajduje również coraz więcej innych zastosowań zarówno we wnętrzach jak i na zewnątrz, gdzie jest narażone na działanie pleśni. Porównano podatność topoli osiki na rozwój często występujących grzybów pleśniowych Aspergillus niger (Tiegh) i Chaetomium globosum ((Kunze)Fr.) do odporności na te grzyby bielu drewna dębowego (Quercus sp.). W wyniku badań wykazano, że drewno topoli osiki ma mniejszą podatność na rozwój pleśni Aspergillu niż drewno dębu. Podatność na działanie pleśni Chaetomium drewna osiki jest porównywalne z podatnością drewna dębowego choć zaobserwowano mniejszy wzrost grzybni na drewnie osiki. Może to wynikać z mniejszej zawartości składników

53 niestrukturalnych w jej drewnie, a co za tym idzie bardziej ubogiego środowiska dla rozowju grzybów pleśniowych.

Corresponding authors:

Bartłomiej Rębkowski Department of Wood Science and Wood Preservation, Faculty of Wood Technology, Warsaw University of Life Sciences - SGGW, 166 Nowoursynowska St., 02-787 Warsaw Email: [email protected] Phone: +48 602 440 502

Krzysztof J. Krajewski Department of Wood Science and Wood Preservation, Faculty of Wood Technology, Warsaw University of Life Sciences - SGGW, 166 Nowoursynowska St., 02-787 Warsaw Email: [email protected]

Agnieszka Mielnik Department of Wood Science and Wood Preservation, Faculty of Wood Technology, Warsaw University of Life Sciences - SGGW, 166 Nowoursynowska St., 02-787 Warsaw Email: [email protected]

54 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 55-59 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Finger- joints in lamellas of beech wood (Fagus sylvatica L.)

ALENA ROHANOVÁ, PETER KRIŠŠÁK

Abstract: Finger- joints in lamellas of beech wood (Fagus sylvatica L.) Due to the lack of quality spruce construction timber, a new alternatives are being searched and considered, beech (Fagus sylvatica L.) timber mostly. It´s used for many glued elements with finger joints. The usage is conditioned by determining properties according to the legislation. Samples were tested for bending strength (MOR) ,modulus of elasticity (MOE) and density. Finger length lj = 22 mm and gluing with XILOBOND T FJ 10 (w = 12%) were according to EN 14 080:2013. Orientation of finger joints was either horizontal or vertical. Properties were compared to reference samples. Bending strength of finger-jointed samples decreased comparing to reference samples. Better results were received with horizontal orientation of finger joints. Modulus of elasticity was higher in compare with reference samples. In horizontal direction MOE was higher in average 10%. At the same time a new technology of gluing joints was tested. Bonding of beech timber by finger joints can be used in truss production.

Keywords: beech wood, finger joint, modulus of rupture, modulus of elasticity, horizontal and vertical direction

INTRODUCTION

In European union countries there is general lack of quality coniferous raw material. Therefore new alternative woods are searching, of which the most interesting is beech wood. Usage of beech timber in building construction is much more difficult and complicated than usage of spruce timber. Beech proccessing disadvantages (crookedness, inner stresses, rot and others) are eliminating his usage mostly in load-bearing constructions. The usage is conditioned by determining properties accroding to legislation. EN 14 080:2013 lists a glued product assortment that use various finger length (lp ∼ 15 to 30 mm). Perspective utilization is in lineal and curved hybrid crossection elements (ROHNER 2013), which are connected by large finger joints (lp › 45 mm). Finger joints in joists are given in the Figure 1.

Figure 1. I-joists with finger joints

MATERIAL AND METHODS

Beech timber (Fagus sylvatica L.) was used for the experimental testing. Dimensions of test samples are given in the table 1.

Table 1. Dimensions of test samples

b h l Number Type of sample Direction [mm] [mm] [mm] of samples 26 38 480 finger-jointed vertical 24 38 26 350 finger-jointed horizontal 20 26 38 480 reference vertical 3 38 26 350 reference horizontal 6

Test samples were conditioned for 12 ± 2% moisture content (relative humidity 65 ± 5 % and 20°C), which is reference moisture content according to EN 384.

Samples were divided in two groups after the conditioning:

• reference samples: load direction:

horizontal b › h vertical h › b

• finger - jointed samples: finger direction:

horizontal vertical

Finger joints were glued with polyurethane glue XLOBOND T FJ 10 with wood moisture content w = 12 ±2 % (figure 2.). Test samples were tested in four-point bending test according to EN 408.

Figure 2. Finger joints

RESEARCH RESULTS

Results of experimental tests were evaluated with mathematic-statictical methods. Basic statistic characteristics, 3-factor ANOVA (variables: bendind strength fm, modulus of elasticity E, factors: finger direction: horizontal (hj), vertical (vj), type of the sample: finger- jointed, reference sample (ref.)) were described.

Table 1 Basic statistical characteristics of beech samples

Beech timber Vertical Horizontal Finger-jointed Reference Finger-jointed Reference Quality Statistical sample sample sample sample

parameters parameters

n [pc] 24 3 20 6

_ Modulus x 25 91 27 98 of rupture min 16 88 19 95 [MPa] max 33 95 37 108 V [%] 18 4 21 5 n [pc] 24 3 20 6

_ Modulus x 14 362 11 374 15 925 11 034 of elasticity min 12 516 11 081 11 792 10 438 [MPa] max 16 442 11 598 21 776 11 886 V [%] 7 2 14 4 n [pc] 5 3 5 3

_ x 733 712 733 712 Density wood 671 688 671 688 [kg.m-3] min max 795 756 795 756 V [%] 6 4 6 4

Bending strength of finger-jointed samples is in average just 26% of the bending strength of reference samples. Horizontal finger joints had higher strength than vertical. Modulus of elasticity increased significantly. Samples with horizontal orientation of finger joint had higher modulus of elasticity in average 44%. We can assume that in different average values of modulus of elasticity depends on the orientation of finger joints. Beech timber proves higher dependance in horizontal direction (r = 0,62) than in vertical (r = 0,47). With lower modulus of elasticity (up to 15 000 MPa) is bending strength higher in horizontal direction, after 15 000 MPa it´s higher in vertical direction (figure 3.).

34 fj,beech,V = -1,305 + ,00182 * Ej,beech,V

r = 0,42 Figure 3. Dependance of 32 (MPa) bending strength to modulus of fj,beech,H = 2,7224 + ,00155 * Ej,beech,H 30 elasticity for beech samples r = 0,62 j,beech,H,V 28 (direction – vertical, horizontal) 26

24 Modulusf ofrupture 22

18 10000 12000 14000 16000 18000 20000 22000 24000

Modulus of elasticity Ej,beech,H,V (MPa)

CONCLUSIONS Experimental testing of finger-jointed beech samples has shown remarkable lower values of bending strength in both directions (horizontal, vertical) comparing to the reference samples. It is assumed that a reason of the decrease can be new experimental confirmed technology of finger joint production and gluing (milling factors, glue type, pressing process and other). The values of modulus of elasticity were higher in both directions in compare to reference samples (36 to 53%). Horizontal orientation of finger joints is more suitable for timber elements with small crossection.

AKNOWLEDGMETS

This study was supported by project under the contract VEGA No. 1/0395/16.

REFERENCES

1. ROHNER, T. (2013): Hybridní stavby. 17. Odborný seminář dřevostaveb ve Volyni. Vyšší odborná škola a Střední prumyslová škola. Volyně 2013. str. 265 – 276. ISBN 978-80- 86837-51-2. 2. EN 408: 2013, Timber structures. Structural timber and glued laminated timber. Determination of some physical and mechanical properties. 3. EN 14080: 2013, Timber structures. Glued laminated timber and glued solid timber. Requirements. 4. EN 338: 2010, Structural timber. Strength classes.

58 Streszczenie: Połączenia wczepowe lamelek w drewnie buka (Fagus sylvatica L.) W związku z brakiem wysokojakościowej tarcicy świerkowej, rozważane są alternatywy, m.in buk (Fagus sylvatica L.) Badania przeprowadzone zgodnie z normą EN 14 080:2013 wykazały że nowoopracowana techologia połączń wczepowych może być zastosowana I belki bukowe wytworzone tą metodą mogą być stosowane do produkcji więźby.

Author´s address doc. Ing. Alena Rohanová, PhD. Ing. Peter Kriššák Katedra drevených stavieb Drevárska fakulta Technickej univerzity T.G. Masaryka 24, 960 53 Zvolen [email protected], [email protected]

59 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 60-64 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Poplar wood (Populus tremula L.) findings of finger - jointed timber

ALENA ROHANOVÁ, PETER KRIŠŠÁK

Abstract: Poplar wood (Populus tremula L.) findings of finger-jointed timber. Poplar wood can be classified into strength classes C14- C40 from the construction timber quality point of view. Due to the lack of a spruce construction timber, poplar wood can be used instead. Length extension of lamells with finger-joints is required for the construction timber. Poplar timber with finger joints was tested. Finger length lj = 22 mm and gluing with XILOBOND T FJ 10 (w = 12%) were according to EN 14 080:2013. Testing samples with crossection 26x38 mm were tested according to EN 408 for bending strength (MOR) and modulus of elasticity (MOE) in horizontal and vertical orientation of finger joints. Results were compared with reference samples. Bending strength of finger-jointed samples decreased comparing to reference samples. Modulus of elasticity was higher in compare with reference samples in both directions (horizontal, vertical) from 36 to 53%. Similar profiles can be used in truss production with elements connected by GANG-NAIL. Theoretical and experimental analyses are required according to EN 14 080:2013.

Keywords: poplar wood, finger joint, modulus of rupture, modulus of elasticity, horizontal and vertical direction

INTRODUCTION Spruce and fir timber is used for building construction, classified as one category according to EN 338 nowadays. This category includes also poplar wood. The supplies of quality spruce raw material in the Slovak Republic and other countries are decreasing because of a climate change, frequent windstorms, exported timber abroad. Due to these reasons other wood species should be also utilized (ROHANOVÁ 2013).

Finger joints in glued products represent sophisticated joints, which allows high quality construction elements with shape and dimension diversity. Joint is made by fingers and glue and is recommended for use after testing. Strength and elasticity characteristics of elements are influenced by shape and length of finger joints (small, medium, large), type of material (wood species) and glue. Requirements for glued products and minimal production requirements of finger joints (medium, large) are stated in EN 14080:2013. It defines the profile, shape and dimensions of finger joints (Figure 1). Examples of different applications are shown in Figure 2.

Figure 1. Profile and geometry of finger joint (EN 14080: 2013) (lj - finger length, p – tip spacing, bt – tip width, v –reduction factor v = bt /p )

Figure 2. Various sizes of finger joints

MATERIAL AND METHODS

Aspen poplar timber (Populus tremula L.) was used for the experimental testing. Dimensions of test samples are given in the table 1.

Table 1. Dimensions of test samples

b h l Number Type of sample Direction [mm] [mm] [mm] of samples 26 38 480 finger-jointed vertical 15 38 26 350 finger-jointed horizontal 11 26 38 480 reference vertical 3 38 26 350 reference horizontal 4

Test samples were conditioned for 12 ± 2% moisture content (relative humidity 65 ± 5 % and 20°C), which is reference moisture content according to STN EN 384.

Samples were divided in two groups after the conditioning:

• reference samples: load direction:

horizontal b › h vertical h › b

• finger - jointed samples: finger direction:

horizontal vertical

Finger joints were glued with polyurethane glue XLOBOND T FJ 10 with wood moisture content w = 12 ± 2 %. Test samples were tested in four-point bending test according to EN 408.

RESEARCH RESULTS

Table 1. Basic statistical characteristics of poplar samples

Poplar timber Vertical Horizontal Finger-jointed Reference Finger-jointed Reference Quality Statistical sample sample sample sample

parameters parameters

n [pc] 15 3 11 4

_ Modulus of rupture x 26 69 26 75 min 20 65 19 59 [MPa] max 34 75 35 83 V [%] 15 7 17 12 n [pc] 15 3 11 4 Modulus of _ 12 774 9 149 14 384 9 590 elasticity x min 10 859 8 241 10 169 8 116 [MPa] max 16 503 9 763 17 009 10 961 V [%] 12 7 14 13 n [pc] 5 3 5 3

_ Density wood x 560 562 560 562 min 529 547 529 547 [kg.m-3] max 595 573 595 573 V [%] 5 2 5 2

Higher dependance was determined in vertical direction (r = 0,54) than in horizontal direction (r = 0,47), figure 3. Bending strength is higher in vertical direction and with growing modulus of elasticity the difference is getting higher.

62 36

(MPa) (MPa) Figure 3. Dependance of bending

fj,top-V = 7,9861 + ,00143 * Ej,top V strength to modulus of elasticity for 28 j,top- H, V j,top- r = 0,54 poplar samples

26 (direction – vertical, horizontal) fj,top H = 11,547 + ,00103 * Ej,top H 24 r = 0,47 Pevnosť v ohybe f

18 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 Modul pružnosti v ohybe Ej,top- H, V (MPa) CONCLUSIONS

Experimental testing of finger-jointed poplar samples has shown remarkable lower values of bending strength in both directions comparing to the reference samples (horizontal – 35%, vertical - 38%). It is assumed that a reason can be new experimental confirmed technology of finger joint production and gluing (milling factors, glue type, pressing process and other). The values of modulus of elasticity were higher in both directions in compare to reference samples (40 to 50%). Vertical orientation of finger joints is more suitable for timber elements with small crossection.

AKNOWLEDGMETS This study was supported by project under the contract VEGA No. 1/0395/16.

REFERENCES

1. BUSTOS, C. - BEAUREGARD, R. - MOHAMMAD, M. 2001. Effect of joint geometry on the performance of structural finger-jointed black spruce wood.s.503. Joints in Timber Structures, 2001. 653s. ISBN: 2-912143-28-4. 2. ROHANOVÁ, A. 2013. Predikcia parametrov kvality smrekového konštrukčného dreva. Technická Univerzita vo Zvolene, 2013. 79s. ISBN: 978-80-228-2631-0. 3. EN 408: 2013, Timber structures. Structural timber and glued laminated timber. Determination of some physical and mechanical properties. 4. EN 14080: 2013, Timber structures. Glued laminated timber and glued solid timber. Requirements. 5. EN 338: 2010, Structural timber. Strength classes.

63 Streszczenie: Badania nad połączeniami wczepowymi w drewnie topoli (Populus tremula L.). Topola z punktu widzenia drewna konstrukcyjnego może być kwalifikowana do klas C14- C40. W związku z ograniczoną dostępnością drewna świerkowego, można stosować drewno topoli jako zamiennik. Testowano połączenia wczepowe w drewnie topoli i porównywano z próbkami referencyjnymi. Wykazano niższą wytrzymałość próbek klejonych, przy zwiększonym module sprężystości. Badany materiał może być wykorzystany w produkji więźby, wymaga jednak analiz teoretycznych I eksperymentalnych zgodnie z normą EN 14 080:2013.

Corresponding author:

doc. Ing. Alena Rohanová, PhD. Ing. Peter Kriššák Katedra drevených stavieb Drevárska fakulta Technickej univerzity T.G. Masaryka 24, 960 53 Zvolen [email protected], [email protected]

64 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 9X, 2016: 65-70 (Ann. WULS - SGGW, For. and Wood Technol. 9X, 2016)

Клеевое соединение между основанием и древесиной как фактор стабилизирующий дубовые половые дощечки

VALERJAN ROMANOVSKI, PAWEŁ KOZAKIEWICZ, MARIUSZ MAMIŃSKI, ALBINA JEGOROWA Факультет Технологии Древесины, Варшавский Университет Естественных Наук – SGGW

Резюме: Клеевое соединение между основанием и древесиной как фактор стабилизирующий дубовые половые дощечки. Долговечность пола из древесины в высокой степени зависит от качества соединения дощечки из массива с основанием. Клеевое соединение подвержено воздействию сдвигающих и отрывающих сил, которые генерируются дощечкой, в следствии изменения размеров в процессе эксплуатации.В статье проанализировано в какой степени, клеевое соединение в состоянии уменьшить разбухание дощечки из массива, приклеенной к основанию. Для исследований использовалось клеевое соединение характеризующееся высокой степенью жесткости. Определен предел прочности соединения древесины с основанием, а также проанализировано, какое влияние на долговечность полового покрытия имеет степень смачивания дощечки клеем. Исследования проводились с использованием древесины дуба.

Ключевые слова: Деревянные полы, клеевое соединение, стабильность размеров, половая дощечка, древесина дуба

ВВЕДЕНИЕ Материалы для изготовления полов, исходя из экономических условий все чаще имеют слоистое строение. Верхний слой (рабочий) изготавливается из ценных пород с высокими визуальными и механическими качествами, гарантирующими устойчивость к вмятинам и стиранию [Kozakiewicz 2015, Kozakiewicz, Pióro, Noskowiak 2012]. Нижние слои обычно изготовлены из более дешевой древесины и служат для стабилизации элементов полового покрытия. Направление волокон в стабилизирующем слое (похоже как у фанеры) чаще всего перпендикулярно к направлению волокон верхнего слоя и благодаря этому усушка элемента становится более равномерной [Wagenfuhr 2007, Jankowska, Kozakiewicz, Szczęsna 2012]. Техника укладки деревянных полов во многих случаях связана с постоянством соединения их с основанием, что имеет особое значение для елементов из массива. Такое решение способствует стабилизации половой древесины, которая подвержена размерным изменениям вытекающим из натуральных, ежегодных микроклиматических перепадов в помещениях с центральным отоплением [Romanovski 2012, Kozakiewicz, Matejak 2013]. Производители клеев для полов предлагают продукты с различными механическими параметрами, т.е. прочности полученные на базе их соединений [Romanovski 2014]. Клей с различной прочностью на сдвиг, растяжение и упругостью по разному стабилизирует массивную древесину. Этот фактор зничительно влияет на поведение древесины пола, т.е. на величину щелей и деформаций появляющихся в результате изменений микроклимата в помещениях. Целью исследования было определение в какой степени клеевое соединение в состоянии стабилизировать дощечку из массива, а так же при каком максимальном разбухании древесины она будет оторвана. Определено так же влияние степени покрытия дощечки клеем на повреждение клеевого соединения.

65 МЕТОДИКА ИССЛЕДОВАНИЯ Для исследований были использованы элементы из твердой древесины дуба (Quercus robur L.) размерами: длина 250 мм, ширина 150 мм и толщина 20 мм в количестве 35 штук. Образцы имели прежде всего систему слоев с доминирующими тангенциальными разрезами на пластях. Таким образом подготовленные образцы были приклеены на фанеру из березы толщиной 50 мм (Рис.1).

Рис.1. Дубовые дощечки закрепленные на основании при помощи клея

Клей был положен в перпендикулярном направлении по отношению к направлению волокон дощечки при помощи шпателя B11. Инструмент с зубцами рекомендуется для приклеивания как паркетов так и дощечек [Wolski 2007]. Использованный способ наложения гарантирует расход клея около 1 кг/м2. На части исследуемых образцов, 26 штук, клей был наложен на 70 % поверхности, на оставшихся 9 штуках на 90 %. После получения абсолютной прочности шва (72 часа) соединенные наборы были помещены в климатическую камеру, ранее определив начальную влажность древесины и размер (ширина). В камере была установлена температура 250 С и относительная влажность воздуха 75% на период две недели. После завершения первого этапа кондиционирования выполнено повторное измерение влажности и размеров элементов а так же проверена прочность сединения. Во втором этапе, в камере задана температура 220 С и несколько более высокая относительная влажность воздуха – 80%. По истечении двух недель зафиксированы окончательные результаты. Проанализировано в каких образцах клеевой соединение разрушено, при помощи подцепления их долотом.

Рис.2. Форма и размеры образца: a и b – скленные элементы, с – клеевой шов толщиной 0,6 мм

Для исследования использовано двухкомпонентный клей эпоксидно- полиуретановый фирмы RECOLL 25-2K NEW. Прочностыне параметры соединения на сдвиг определены в с использованием испытательной машины Instron 3369. Форма образцов для определения прочности соединения соответсвовала норме PN – 79/D – 04105. Образец подрезался так, чтобы в области поверхности сдвига находилось исследуемое клеевое соединение (рис.2). Влажность древесины определена электрометрическим способом с использованием влагомера GANN HYDROMETTE BL COMPACT B. Изменения размеров дубовых дощечек определено выражением коэффициента разбухания [Kozakiewicz 2012]:

a − a α = x y [-] ao ⋅ ()Wx − Wy

где: a0 – размер древесины в абсолютно сухом состоянии, Wx, Wy – любые влажности древесины из интервала гигроскопичности, при условии что Wx > Wy, ax, ay – размеры соотвественно при влажности древесины Wx и Wy

РЕЗУЛЬТАТЫ ИССЛЕДОВАНИЙ И ДИССКУСИЯ Средняя влажность дубовых дощечек перед началом эксперимента составляла 8,5 %, стандартное отклонение - 1,99 %. Исследуемый материал был подвержен кондиционированию в два этапа. После окончания процесса увлажнения получена средняя влажность 15,5 %, стандартное отклонение только 0, 39 %. Исследуемый материал был приклеен к фанере не влагостойкой (размещение листов шпона пенпердикулярно) толщиной 50 мм. Выбор толщины фанеры обусловлен обеспечением стабильности основания. В исследованиях использовались контрольные образцы, которые не приклеивались к основанию. После окончания кондиционирования определена величина разбухания контрольного образца и проведено сравнение с результатами полученными на образцах прикленных к основанию. В элементах приклеенных после увлажнения в два этапа отмечено уменьшение разбухания на 46% по сравнению с контрольными образцами. Сравнивания величину разбухания с литературными данными [Kozakiewicz, Pióro, Noskowiak 2012] отмечено снижение разбухания на 45 % (рис.3).

Рис.3. Коэффициент разбухания – процентное изменение ширины исследуемых образцов при изменении влажности древесины дуба на 1%

Анализируя влияние величины увлажнения клеем дощечки отмечена тесная зависимость между прочностью соединения дощечки с основанием и процентным увлажнением дощечки. После первого этапа кондиционирования (увлажнения) не отмечено нарушения клеевого соединения. После увлажнения во втором этапе в дощечках покрытых клеем на 90% не отмечено разрушения соединения под влиянием разбухания древесины дуба в результате увеличения влажности с 8,5 до 15,5 %. В дощечках покрытых клеем на 70 % соединение было разрушено на 18 образцах из 26 исследуемых (рис.4).

Рис.4. Пример разрушенного клеевого соединения в результате разбухания дощечки

Чтобы оценить прочность клеевого соединения (ее стабилизуруюшее воздействие) изготовлены образцы с размерами и формой предстваленными на рис. 2 и осуществлена попытка сдвига. Толщина клеевого соединения составила 0,6 мм, а полученная прочность на сдвиг 6, 86 MПa. Это типичная прочность соединений на базе монтажных клеев используемых в столярных изделиях [Kurowska, Kozakiewicz 2010]. Полученные результаты имеют большое практическое значение, показывая существенное улучшение стабильности деревянных полов изготовленных из дубовых дощечек при их солидном соединении с основанием при помощи клеевого шва.

68 Нанесение клея на тыльную сторону дощечки должно обеспечивать 90 % ее покрытия. В полах используемых в микроклиматических условиях помещениий с центральным отоплением эта операция (жесткое соединение с основанием) отразится на появлении меньших щелей и деформаций в период отопительного сезона.

ВЫВОДЫ Результаты проведенных исследований позволяют сформулировать следующие выводы: 1. При использовании “жесткого” клеевого соединения при симуляции типичных изменений влажности воздуха в помещениях с центральным отоплением в течении года, коэффициент разбухания дубовых половых дощечек уменьшается примерно на 50% по отношению к дощечкам свободным ( не соединенным с основанием). 2. Степень увлажнения (покрытия) тыльной стороны половой дощечки клеем существенно влияет на прочность полов из массивной древесины (сопротивление соединения на отрыв). В примененных условиях 70% -ное покрытие не является достаточным (выступает разрушение соединения). При 90%-ном покрытии, соединения не разрушаются ( прочность клеевого соединения порядка 7 MПа обеспечивает долговечность).

ЛИТЕРАТУРА 1. JANKOWSKA A., KOZAKIEWICZ P., SZCZĘSNA M., 2012: Drewno Egzotyczne Rozpoznawanie Właściwości Zastosowanie Wydawnictwo SGGW. Warszawa. 2. KOZAKIEWICZ O., 2012: Fizyka drewna w teorii i zadaniach. Wydanie IV zmienione. Wydawnictwo SGGW. Warszawa. 3. KOZAKIEWICZ P., 2005: Drewno w budownictwie – podłogi. Przemysł Drzewny nr 6 2005, str.6 -11. Wydawnictwo Świat. 4. KOZAKIEWICZ P., MATEJAK M., 2013: Klimat a drewno zabytkowe – dawna i współczesna wiedza o drewnie. Wydanie IV zmienione. Wydawnictwo SGGW Warszawa. 5. KOZAKIEWICZ P., PIÓRO P., NOSKOWIAK A., 2012: Atlas drewna podłogowego. Wydawnictwo Profi-Press Sp. z o.o. Warszawa. 6. KUROWSKA A., KOZAKIEWICZ P., 2010: Density and shear strength as solid wood and glued laminated timber suitability criterion for window woodwork manufacturing. Annals of Warsaw University of Life Sciences – SGGW Forestry and Wood Technology No 71, 2010: 429-434. 7. PN-79/D-04105 Drewno. Oznaczenie wytrzymałości na ścinanie wzdłuż włókien. 8. ROMANOVSKI V., 2012: Wpływ warunków klimatycznych w pomieszczeniu na zmiany wilgotności równoważnej i wymiaru wybranych gatunków drewna. Praca inżynierska na kierunku technologii drewna. SGGW Warszawa. 9. ROMANOVSKI V., 2014: Systemy wzmacniania podkładów mineralnych pod podłogi z drewna litego. Praca magisterska na kierunki technologia drewna, wykonana pod kierunkiem dr hab. inż. Mariusza Mamińskiego w Katedrze Technologii i Przedsiębiorczości w Przemyśle Drzewnym, WTD, SGGW w Warszawie. 10. WAGENFÜHR R., 2007: Holzatlas.6., neu bearbeitete und erweitere Auflage. Mit zahlreichen Abbildungen. Fachbuchverlag Leipzig im Carl Hanser Verlag, München. 11. WOLSKI Z., 2007: Parkieciarz – podstawy wiedzy i praktyki zawodowej. Stowarzyszenie Parkieciarze Polscy. Warszawa.

Streszczenie: Spoina klejowa między podkładem a drewnem jako czynnik stabilizujący dębowe deszczułki posadzkowe. W badaniu określono w jakim stopniu połączenie litych deszczułek posadzkowych wpłynie na stabilizację ich wymiarów. Ponadto przeanalizowano jakie znaczenie na trwałość połączenia deszczułki z podkładem ma powierzchnia zwilżenia (pokrycia) jej spodniej powierzchni klejem. Przy zastosowaniu ,,sztywnej” spoiny klejowej przy symulacji typowych rocznych zmian wilgotności powietrza w pomieszczeniach z centralnym ogrzewaniem, współczynnik spęcznienia dębowych deszczułek posadzkowych zmniejsza się o ok. 50% w stosunku do deszczułek swobodnych (nie zespolonych z podłożem). Stopień zwilżenia (pokrycia) spodu deszczułki posadzkowej klejem istotnie wpływa na trwałość posadzki z drewna litego (odporność spoiny na zerwanie). Przy zastosowanych warunkach 70% pokrycie nie jest wystarczające (następuje zrywanie spoin). Przy 90% pokryciu, spoiny pozostają całe (wytrzymałość spoiny klejowej rzędu 7 MPa zapewnia trwałość połączenia).

Corresponding authors:

Valerjan Romanovski Katedra Nauki o Drewnie i Ochrony Drewna Wydział Technologii Drewna Szkoła Główna Gospodarstwa Wiejskiego w Warszawie ul. Nowoursynowska 159 02-776 Warszawa, Polska e-mail: [email protected] tel: +48 22 59 38 658

Paweł Kozakiewicz Katedra Nauki o Drewnie i Ochrony Drewna Wydział Technologii Drewna Szkoła Główna Gospodarstwa Wiejskiego w Warszawie ul. Nowoursynowska 159 02-776 Warszawa, Polska email: [email protected] http://pawel_kozakiewicz.users.sggw.pl tel: +48 22 59 38 647

Mariusz Mamiński Katedra Technologii i Przedsiębiorczości w Przemyśle Drzewnym Wydział Technologii Drewna Szkoła Główna Gospodarstwa Wiejskiego w Warszawie ul. Nowoursynowska 159 02-776 Warszawa, Polska email: [email protected] tel: +48 22 59 38 527

Albina Jegorowa Katedra Mechanicznej Obróbki Drewna Wydział Technologii Drewna Szkoła Główna Gospodarstwa Wiejskiego w Warszawie ul. Nowoursynowska 159 02-776 Warszawa, Polska email: [email protected] tel: +48 22 59 38 577

70 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 71-76 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The effect of long-time storage of PRF resin on its physical and chemical properties

ANNA ROMANOWSKA, MARIUSZ MAMIŃSKI Department of Technology and Entrepreneurship in Wood Industry, Faculty of Wood Technology, Warsaw University of Life Sciences – SGGW

Abstract: The effect of long-time storage of PRF resin on its physical and chemical properties. Phenol- resorcinol-formaldehyde resin was subjected to 21-month storage and its physical and chemical properties, as well as bondline shear strength made on solid beech wood were observed. It was found that – throughout the experiment – viscosity increased from 3300 to 112000 mPas and gel time at 20°C shortened from 75 to 14 minutes. Microscopic analysis revealed no forming of inhomogeneous solid particles in the resin. The mechanical properties of the bondlines made of the aged resin remained unchanged during 21-month storage.

Keywords: phenol-resorcinol-formaldehyde, storage, bondline properties

INTRODUCTION Phenol-resorcinol-formaldehyde resins (PRFs) are widely used cold-setting adhesives in manufacturing of engineered timber products for the structural applications in building constructions. PRFs are known to exhibit excellent durability under outdoor conditions and high resistance to water as well as stability in a wide range of temperatures. That is why PRFs are used as the binders in production of glue laminated timber (GLT) or cross-laminated timber (CLT) (Brandner et al. 2016) as well as for bonding of green timber (Mantanis et al. 2011). Usually the phenol-resorcinol-formaldehyde resins are synthesized by grafting resorcinol on the PF resin. Subsequently, PRF typically contains 16-18% of resorcinol at the end of the molecule (Pizzi and Mittal 2003) which provides rapid curing under certain conditions. High reactivity of the resin, even without a hardener, can be a drawback during long- term storage when resin molecules undergo slow polycondensation which is mainly manifested by gradually increasing viscosity and a decrease in reactivity that results from the depletion of free resorcinol molecules at the ends of macromolecule chains as well a reduction of abundance of methylol groups (–CH2OH). In the industrial practice a resin stability and changes in its characteristics during storage are essential. As Proszyk (1986) indicates stability is a feature of a product that is associated with the retaining of its technical and application properties during storage. Therefore, the present work is aimed at the 21-month observations and analysis of the characteristics (gel time, viscosity, solids content, bondline shear strength) of a commercial PRF resin.

MATERIALS AND METHODS A commercial phenol-resorcinol-formaldehyde adhesive system was used in the experiments: PRF resin and a solution of paraformaldehyde in glycol (hardener). Viscosity of the resin was measured at ambient temperature on a Brookfield DV-II+ Pro viscometer equipped with a spindle no. 64. For solids content measurement, the resin was dried at 103°C until constant weight. Then the following equation was used:

71 S =100 − [(m −m10 )⋅100%] m0 where: S – solids content, m0 – sample weight prior to drying, m1 – sample weight after drying. Adhesive formulation and bonding were done according to the manufacturer indications i.e. PRF and hardener were mixed in 100/20 weight ratio. The adhesive spread was 400 g/m2. The samples were bonded at ambient temperature under pressure of 1.0 N/mm2 for 24 hrs. The bonded samples were kept at 20 ±2ºC and 65 ±5% relative humidity for 7 days until testing. Then were subjected to water soaking for 72 hrs or 3-hr boiling in water. Gel times were determined at 20°C on the aluminum trays of 50-mm diameter. Shear strength tests were performed on beech (Fagus sylvatica) wood specimens according to EN 301-2 standard (density 700±30 kg/m3, 5.5% moisture content). Twenty samples were tested in each series. Light microscopy analyses were performed using an Olympus BX41 (Olympus Deutschland GmbH, Germany) microscope.

RESULTS It is well recognized that both phenolic and amino resins ageing renders gradual increase in their viscosity (Christjanson et al. 2002) that results from a slow growth of the molecules. Thus, the changes in viscosity of the PRF were examined throughout the whole 21-month investigation period. The results are shown in Fig. 1. As far as application properties of a resin are concerned, slow polycondensation during resin storage results in an increased degree of condensation and in the reduction in abundance of methylol groups (Monni et al. 2007) which, subsequently, affects its reactivity and gel time. The observed gel time shortened throughout the storage (Fig. 1a). The phenomenon can be explained by the substantial increase in the resin viscosity (Fig. 1b): since the PRF viscosity on 9th, 15th and 21st month was higher than initial on month 0, the gel point was achieved after the shorter time. Hence, the effect of a decreased reactivity was apparently overwhelmed by the effect of viscosity.

Figure 1. Changes in gel time (a) and resin viscosity (b)

The observation remains with the general knowledge on the nature of chemoreactive adhesives. The obtained results clearly indicate that after 10-12 months the viscosity exceeded the threshold value of 10 000 mPas and became hardly useful in terms of application in construction. Such high viscosity limits penetration of the adhesive into the substrate which yields a bondline of insufficient thickness. The relation is described by the Poiseulle law:

dx r 2P x dt = 8η where: x – penetration depth, η – viscosity of a liquid, P – capillary pressure, t – time, r – pore diameter. Another parameter that was observed was solids content. The results are presented in Fig. 2. The data suggests that the concentration of the resin was not significantly affected. It was possible mainly because of the use of original tightly-closed boxes for storage. Though solids content remained constant, the chemical structure of the resin was altered which manifested by increased viscosity.

100

40 solids content (%) content solids

10 0 5 10 15 20 25 storage time (months)

Figure 2. PRF resin solids content during long-term storage.

The analysis of the resin morphology by the means of optical microscopy showed that, unlike the amino resins (Jóźwiak 2011, Pałka and Mamiński 2016), PRFs do not form aggregates large enough for optical microscope and remain transparent until the 20th month of the experiments (Fig. 3). That finding clearly confirmed that the examined PRFs are more stable during storage than melamine-urea-formaldehyde resins.

Figure 3. Microscopic picture of the PRF resin after 20-month storage

The shear strengths and wood failure rate of the bondlines made of the aged PRF are shown in Fig. 4a and 4b, respectively. One can see that the storage time did not significantly affect the tensile shear strength. The standard deviations indicate that the respective values obtained for dry, soaked and boiled series remain comparable and exhibit no statistically significant differences. Minding that regardless of the storage time, the wood failure rates were high and exceeded 90% (Fig. 4b). The only outlier result was observed for the 12-month old dry bondline (75%) which could have been caused by an uncontrolled substrate surface contaminations or inhomogeneous adhesive spreading on a portion of the specimens. The variable shear strengths were associated with the variations in the mechanical strength of the wood applied as the substrate. Similar results – i.e. 100% wood failure for shear strength about 8 MPa – were reported by Mamiński et al. (2011).

Figure 4. Shear strength and wood failure rate in bondline

74 Though PRFs are known to be fully resistant to exterior conditions (EN 302-1), they may exhibit lower performance under severe laboratory tests. As Šernek et al. (2008) report the bondlines of phenol-resorcinol adhesives failed at 2.9-3.8 MPa and exhibited wood failure rate as low as 13–82%, while Adamopoulos and co-workers (2012) found 60% wood failure rate for the water soaked and 90% for dry beech wood specimens.

CONCLUSIONS The presented results confirmed that long-term storage of a PRF resin did markedly increase its viscosity beyond the technical and application range. No forming of large solid particles was evidenced. Gel times were found to shorten with time. However, the mechanical properties of the bondlines made after 3, 6, 12 and 21 months of resin ageing remained unchanged during ageing.

REFERENCES

1. ADAMOPOULOS S., BASTANI A., GASCÓN-GARRIDO P., MILITZ H., MAI C., 2012: Adhesive bonding of beech wood modified with a phenol -formaldehyde compound, Eur. J. Wood Prod., 70; 897–901 2. BRANDNER R., FLATSCHER G., RINGHOFER A., SCHICKENHOFER G., THIEL A., 2016: Cross laminated timber (CLT): overview and development, Eur. Wood Prod. J., 74; 331–351 3. CHRISTJANSON P., SIIMER K., PEHK T., LASN I., 2002: Structural changes in urea-formaldehyde resins during storage, Holz Roh.Werkst., 60; 379–384 4. EN 302-1, 2006: Adhesives for load-bearing timber structures ― Test methods. Part 1: Determination of longitudinal tensile shear strength. 5. JÓŹWIAK M., 2011: Badania fizykochemicznych procesów zachodzących w czasie starzenia się klejowych żywic MUF, rozprawy naukowe nr 423, Uniwersytet Przyrodniczy w Poznaniu 6. MAMIŃSKI M., CZARZASTA M., PARZUCHOWSKI P., 2011: Wood adhesives derived from hyperbranched polyglycerol cross-linked with hexamethoxymethylmelamines, J. Adhes. Adhes., 31; 704-707. 7. MANTANIS G., KARASTERGIOU S., BARBOUTIS I., 2011: Finger jointing of green Black pine wood (Pinus nigra L.), Eur. J. Wood Prod., 69; 155–157 8. MONNI J., ALVILA L., PAKKANEN T.T.,, 2007: Structural and physical changes in phenol−formaldehyde resol resin, as a function of the degree of condensation of the resol solution, Ind. Eng. Chem. Res., 46; 6916–6924 9. PAŁKA I., MAMIŃSKI M., 2016: The effect of long-time storage of PRF resin on its physical and chemical properties, Ann. WULS – SGGW. For. And Wood Technol. (in press) 10. PIZZI A., MITTAL K.L., 2003: Handbook of adhesive technology. Second edition, revised and expanded. Marcel Dekker Inc., New York 11. PROSZYK S., 1986: Stabilność żywic mocznikowo-formaldehydowych podczas magazynowania, Przem. Drzewny, 38; 24–28 12. ŠERNEK M., BOONSTRA M., PIZZI A., DESPRES A., GERARDIN P., 2008: Bonding performance of heat treated wood with structural adhesives, Holz Roh Werkst., 66; 173-180

75 Streszczenie: Wpływ długookresowgo magazynowania na fizyczne i chemiczne właściwości żywicy PRF. Żywica PRF została poddana 21-miesięcznemu magazynowaniu, w trakcie którego obserwowano jej właściwości fizyczne, chemiczne oraz wytrzymałość na ściananie spoin wykonywanych na drewnie bukowym. Stwierdzono wzrost lepkości z 3300 do 112000 mPas i skrócenie czasu żelowania w temperaturze 20°C z 75 do 14 minut. Analiza mikroskopowa nie wykazała tworzenia agregatów. Okres składowania żywicy nie wpłynął znacząco na właściwości mechaniczne otrzymywanych spoin.

Corresponding author:

Mariusz Mamiński Faculty of Wood Technology Warsaw University of Life Science – SGGW 159 Nowoursynowska St. 02-776 Warsaw, Poland e-mail: [email protected] phone +48 22 593 85 27

76 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 77-81 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Fire resistance of timber floors – part 1: Design method

PAWEŁ ROSZKOWSKI*, PAWEŁ SULIK* * Fire Research Department, Building Research Institute

Abstract: The paper presents a design method of fire resistance verification of timber floors. Arrangements of EN 1995-1-2 was used for design method. The test method is presented in part 2.

Keyword: fire resistance, fire resistance tests, timber floors, loadbearing structure

INTRODUCTION The fire resistance of floors is related with the following criteria: R (loadbearing capacity), E (integrity) and I (insulation). This basic terms connected with fire resistance are defined in the standard EN 13501-2 [4] and described in the articles [8, 9, 10, 11] part 2. Requirements for fire resistance of floors depending on the fire resistance class of the building, defined in the regulation [1], are presented in Table 1.

Table 1. Requirements for fire resistance of building’s elements based on the Regulation [1] Fire resistance class of wall elements Building's fire class Main loadbearing construction Floor 1) “A” R 240 REI 120 “B” R 120 REI 60 “C” R 60 REI 60 “D” R 30 REI 30 “E” (–) (–) 1) if the floor is the part of the main loadbearing construction, it should also meet the criteria for fire loadbearing capacity (R)

In accordance to the currently applicable regulation [1] the highest fire resistance class required for floors is class REI 120. However, if a floor is part of a main loadbearing construction, it should meet fire resistance class R 240. If the fire resistance class of floor is necessary to define, we can choose a one method from two available. The first is a design method according to EN 1995-1-2 [3]. The second one is a test method – according to EN 1365-2 [6] corresponding with EN 1363-1 [5] (general requirement). The test method is described in part 2. The general European standards that describes the design procedures for timber structures in normal temperature is standard EN 1995-1-1 [2], while in fire – standard EN 1995-1-2 [3]. The design guide [7] is an useful work to calculate of fire resistance structures for fire conditions according to Eurocode 5.

TYPE OF FLOORS The calculation models given in EN 1995-1-2 [3] are valid for the following type of floors: a) solid floor: made of vertical or horizontal timber or wood-base boards. The boards can works as main loadbearing member or can occur on the timber beams,

77 b) multi-layer floor with timber joists. The following type of cladding are acceptable: wooden panels, wood-base panels, gypsum plasterboards. The following type of cavity insulation are acceptable: glass or rock fibre, or void cavities. Types of timber floor valid for calculate method in EN 1995-1-2 [3] are shown in figure 1.

a) solid floor with vertical timber members b) solid floor with horizontal timber members (timber members fire unprotected); where: 1 – boards (or panels), 2 – timber joists

c) multi-layer floor with timber joists and void d) multi-layer floor with timber joists and void filled cavity; where: 1 – top boards (or panels), 2 – with insulation; where: 1 – top boards (or panels), void cavity, 3 – timber joists, 4 – bottom boards 2 – inslulation e.g. mineral wool, 3 – timber joists, (or panels) 4 – bottom boards (or panels)

Fig. 1 Test frame with test specimen

STAGES OF DESIGN METHOD Load-bearing function of loadbearing members If the designer want to calculate the load-bearing function of timber floor, he should do the following steps: • make assumptions for normal temperature design: specify the properties of timber, partial factor (γm), modification factor (kmod) according to EN 1995-1-1 [2], • check the ultimate limit states of joists or floor boards according to EN 1995-1-1 [2],

• make assumptions for fire situation: specify the coefficient kfi, ηfi, fire exposure time, chose type of calculation method (reduced cross-section method or reduced properties method), • if the load-bearing timber members are unprotected, calculate charring depth; if the load-bearing timber members are initially protected from fire exposure, calculate start of charring and then failure time of protection and calculate charring depth, • calculate the cross-section after charring and check the ultimate limit states - the design effect of actions for the fire situation should be less equal than corresponding design resistance. Separation function – fire integrity and fire insulation EN 1995-1-2 [3] gives the simplified assumption for the analysis of the separation function. Requirements for integrity are assumed to be satisfied when the requirements for insulation are met and panels remain fixed to the timber members on the unexposed side.

78 If the designer want to calculate the separation function of timber floor, he should verify the following formula:

tins ≥ treq (2.1)

where: tins – time of temperature increase on the unexposed side of the construction in minutes treq – required time of fire resistance for the separating function of the assembly in minutes

The value tins should be calculated as the sum of the contributions of the individual layers used in the construction, according to:

tins = ∑t i,0,ins k pos k j (2.2) i where: tins,0,i – the basic insulation value of layer “i” in minutes, kpos – a position coefficient; kj – a joint coefficient.

The members of formula 2.2 are defined in EN 1995-1-2 and the guide [7]. The formula 2.2 is applicable for timber floors with several layers of cladding. Where a separating construction consists of only one layer, e.g. solid floor, tins should be taken as the basic insulation value of the sheathing and, if relevant, multiplied by kj.

For determine the separation function heat transfer paths through a separating construction, shown in figure 2, should be used.

Key: 1 timber frame member 2 panel 3 void cavity 4 cavity insulation 5 panel joint not backed with a batten or joist 6 position of services a – d heat transfer paths

Fig. 2 Heat transfer paths through a separating construction [3]

CONSTRAINTS IN DESIGN METHOD The design method has some limitations for timber floors. The list of them is presented below: • Classification period of fire resistance of floor with cavities completely filled with insulation: for a standard fire exposure of not more than 60 minutes. • Core material: EN 1995-1-2 [3] does not provide answer to the situation when the spaces between loadbearing members are filled with combustible thermal insulation in the form of increasingly popular expanded polystyrene boards or polyurethane foam

79 (PUR or PIR). For calculation of period of separation function you can use the following types of core: rock fibre, glass fibre or void cavities. • Number of cladding layers for calculation of separation function: The number of cladding limited to two. • Types of claddings: claddings of wood or wood-based materials, gypsum plasterboard type of A, H or F.

When encountering one of the above-mentioned problems, the following solutions can be applied: • using advanced calculation methods, which are described in very vague terms; the proof the correctness of the calculating assumptions made can be very burdensome or even impossible; • estimating the results based on simplified methods available, bearing in mind that responsibility for such actions is to be taken by the designer; so as with advanced calculation methods, the validity of the assumptions made is difficult to confirm. • performing fire resistance tests - test method is describe in part 2.

REFERENCE

[1] Rozporządzenie Ministra Infrastruktury z dnia 12 kwietnia 2002 r. w sprawie warunków technicznych jakim powinny odpowiadać budynki i ich usytuowanie (Dz. Ust. Nr 75 poz. 690) z późniejszymi zmianami (Dz. U. 2015 poz. 1422 t.j.). [2] EN 1995-1-1:2004+AC:2006+A1:2008. Eurocode 5 – Design of timber structures Part 1-1: General – Common rules and rules for building. [3] EN 1995-1-2:2004+AC:2006. Eurocode 5 – Design of timber structures Part 1-2: General – Structural fire design [4] EN 13501-2:2016. Fire classification of construction products and building elements – Part 2: Classification using data from fire resistance tests, excluding ventilation services excluding ventilation services [5] EN 1363-1:2012 Fire resistance tests – Part 1: General Requirements [6] EN 1365-2:2014 Fire resistance tests for loadbearing elements Part: 2 – Roof and floors [7] Woźniak G., Roszkowski P., Projektowanie konstrukcji drewnianych z uwagi na warunki pożarowe według eurokodu 5, Warszawa 2014 r. [8] Roszkowski P. , Sędłak B., Metodyka badań dachów przeszklonych, „Świat szkła” 2011. R. 16, nr 6 s. 50-52. [9] Kram D., Projektowanie obiektów drewnianych z uwzględnieniem wymagań w zakresie odporności ogniowej, „Czasopismo Techniczne” 2007/Kraków, z. 4-A, s. 295-300. [10] Sulik P., Odporność ogniowa konstrukcji drewnianych, „Ochrona Przeciwpożarowa” 2007, nr 4/07, s. 12-13. [11] Sulik P., Odporność ogniowa konstrukcji drewnianych, „Ochrona Przeciwpożarowa” 2008, nr 1/08, s. 2-5.

Streszczenie: Odporność ogniowa drewnianych stropów – Część 1: metoda obliczeniowa. Opracowanie opisuje obliczeniową metodę weryfikacji odporności ogniowej stropów drewnianych. Do metody obliczeniowej wykorzystano ustalenia określone w normie EN 1995-1-2. Badawczy sposób weryfikacji odporności ogniowej opisano w części 2.

Paweł Roszkowski Building Research Institute, Fire Research Department ul. Ksawerów 21; 02-656 Warsaw; POLAND [email protected] phone: 022 56 64 415

81 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 82-86 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Fire resistance of timber floors – part 2: Test method

PAWEŁ ROSZKOWSKI*, PAWEŁ SULIK* * Fire Research Department, Building Research Institute,

Abstract: The paper presents test method fire resistance verification of timber floors. For describe the test method was used arrangements of EN 1365-2 and EN 1363-1. Design method is presented in part 1.

Keyword: fire resistance, fire resistance tests, timber floors, loadbearing structure

EQUIPMENT AND TESTS CONDITIONS OF FIRE RESISTANCE TESTS Equipment and conditions for test method of floors are given in the standard EN 1363-1 [3] and EN 1363-2 [4] whereas the standard EN 1365-2 [5] defines requirements. Floors are tested for the fire applied from below and heating conditions according to the standard temperature–time curve. As defined in the EN 13501-2 [2]: Fire from below floors is generally more critical than fire from above. However, in addition to the classification requirements from below, requirements can also be related to the thickness and quality of the flooring/floor and its subsequent design to safe guard against fire from above. This can also be applicable to other elements which are part of a floor, such as shutters. Furthermore, preparation of the fire test with heating from above is difficult or even impossible for some laboratories to prepare. For example following aspects are difficult to perform: heating of top layer of a test specimen, measurement of deflection, apply the observations from below. In most case the fire resistance tests are carried out in heating conditions according to the standard temperature-time curve. The temperature–time curve is shown in figure 1. Pressure in the test furnace is 20 Pa at 10 cm from the bottom floor surface. The test conditions shall correspond to the requirements specified in standard EN 1363-1 [3]. Thermocouples for average and maximum temperature are distributed over the floor surface in order to verify the fire insulation capacity (parameter I). Standard temperature-time curve 1400 1200 1000

[°C] 800 600 400 Norm 200 min max 0 0 30 60 90 120 150 180 210 240 270 300 330 360 Test time [min]

Figure 1. Diagram of heating curve

82 Loads are taken into consideration in the structure design process. The following types of loads are mainly considered in the fire resistance tests of floor structures: • variable action loads, • loads from structures suspended under the floor, e.g. ventilation systems. When considering the suspended load, its characteristic value is taken into account. The assumed value and distribution of the load shall ensure that the maximum bending moment and shearing forces produced in the test specimen are representative or higher than the actually expected. The test load shall be distributed evenly by a system of spot loads. It is the responsibility of the test ordering entity to decide whether the structure is to be tested as loaded.

TEST SPECIMEN, SUPPORT AND RESTRAINT CONDITIONS FOR FIRE RESISTANCE TESTS The main issue to be addressed when performing verification of fire resistance using test methods is the preparation of a test specimen. When the actual size cannot be accommodated in the furnace, the test specimen should measure at least 3 × 4 m (dimensions of test specimen exposed to fire). One way spanning floor, without ceilings, may have an exposed width between 2 m and 3 m, provided the relevant requirements given in point 6.4 of EN 1365-2 [5] are accommodated. The number of tests to be performed depends on the support and fixing of the specimen, and the specified conditions of heating and loading. Floors are tested with the assumption of simple support (simply supported member), extending in one direction that enables free longitudinal movement and deflection. The surface of the concrete or steel bearings shall be smooth and flat. The width of the bearings shall be the minimum representative of that used in practice and in any case not more than 200 mm [5]. If the support and restraint conditions are differ from the standard conditions previously (above) specified these the validity of the test results should be consequently restricted. The examples test specimens are shown in figure 2, 3, 4 and 5.

Figure 2. Example of test specimen (tested floor viewed from the bottom); where: 1 – free edge (protected with rock mineral wool), 2 – the edge on which the tested member is fixed/supported, 3 – suspended load, 4 –cladding or floor boards (floor top and bottom), 5 – wooden loadbearing beams (along the member to be tested), 6 – floor core, e.g. PIR, EPS.

The moisture content of timber elements has an influence when the tested floor is exposed to fire conditions. High moisture contents can lead to the development of stream pockets which

83 may cause delamination of timber. For this reason loadbearing timber elements used for fire resistance tests should have moisture from 9% to 12 %.

A B

Fig. 3 Floor before the fire resistance test – Fig. 4 Floor after fire test (after removal of the load) – example 1; where: A – a steel weight example 2; where: B – crack

Fig. 5 Floor after fire test – example 3, where: 1 – wooden loadbearing beams

PERFORMANCE CRITERIA The most impotent performance criterion for floor construction is loadbearing capacity (R). For test method failure of loadbearing capacity of floors shall be deemed to have occurred when both of the following criteria have been exceeded: • Deflection: D = L2/(400·d) [mm], • Rate of deflection: dD/dt = L2/(9000 · d) [mm/min], where L is the clear span of the test specimen in mm and a is the distance from the extreme fibre of the cold design zone to the extreme fibre of the cold design tension zone of the structural section, in mm. Fire tests of timber floors show that the failure of floors happens before above criteria are exceed. The reason is that above formulae for deflection and rate of deflection are meant to be universal for different type of construction (timber, concrete, steel etc.). The second criterion is integrity (E) also known as separation function. Integrity is the ability of the element of construction that has a separating function, to withstand fire exposure on one side only, without the transmission of fire to the unexposed side as a result of the passage of flames or hot gases. They may cause ignition either of the unexposed surface or of any material adjacent to that surface.

84 The assessment of integrity for floors shall generally be made on the basis of the following three aspects: • cracks or openings in excess of given dimensions; • ignition of a cotton pad; • sustained flaming on the unexposed side. The regulation [1] from timber floors as a criterion also requires the thermal insulation. The performance level used to define thermal insulation shall be the mean temperature rise on the unexposed face limited to 140°C above the initial mean temperature, with the maximum temperature rise at any point limited to 180 °C above the initial mean temperature.

TEST RESULTS The results of fire resistance tests of loadbearing timber floors as well as timber roofs described in [6] and timber stud walls described in [7] depends on various factors. The most important for timber floors are: • utilization level of load-carrying capacity – the most important element with this type of structures are timber beams, • beams stiffness which is related to their cross-section, the size and spacing of used stiffeners, • type of connections, • spam of the loadbearing beams, • the type of cladding, the number of layers, their thickness and method of attachment, • type of core material.

SUMMARY Design method according to standard EN 1995-1-2 [8] of the timber floors described in part 1 of this paper is very practical. Simplified methods for determining fire resistance are highly useful for the design of typical floor structures. For non-standard solutions or floors with cores the other than rock or glass fibre, or claddings other than wood or wood-based panels or gypsum plasterboards type A, H or F, with top other than wood or wood-based panels or boards, the fire resistance tests seems to be necessary. Please note that great care needs to be taken with the design of an element for fire resistance tests; however, verification with fire tests can bring immense benefits in the form of better fire resistance classifications of test specimens or yield more information about behaviour in fire conditions.

REFERENCE [1] Rozporządzenie Ministra Infrastruktury z dnia 12 kwietnia 2002 r. w sprawie warunków technicznych jakim powinny odpowiadać budynki i ich usytuowanie (Dz. Ust. Nr 75 poz. 690) z późniejszymi zmianami (Dz. U. 2015 poz. 1422 t.j.). [2] EN 13501-2:2016. Fire classification of construction products and building elements – Part 2: Classification using data from fire resistance tests, excluding ventilation services excluding ventilation services [3] EN 1363-1:2012 Fire resistance tests – Part 1: General Requirements [4] EN 1363-2:2001 Fire resistance tests – Part 2: Alternative and additional procedure [5] EN 1365-2:2014 Fire resistance tests for loadbearing elements Part: 2 – Roof and floors [6] Roszkowski P., Sulik P. Fire resistance of roofs with loadbearing wooden beams and fire protective claddings made of magnesium oxide boards, Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology, 2014, nr 87, s. 188-190.

85 [7] Roszkowski P., Sulik P., Sędłak B. Fire resistance of timber stud walls, Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology, 2015, nr 92, s. 368-372. [8] EN 1995-1-2:2004+AC:2006. Eurocode 5 – Design of timber structures Part 1-2: General – Structural fire design

Streszczenie: Odporność ogniowa drewnianych stropów – część 2: Metoda badawcza. Opracowanie opisuje metodę badawczą weryfikacji odporności ogniowej stropów drewnianych. Do określenia odporności ogniowej w sposób badawczy wykorzystano ustalenia określone w normach EN 1365-2 oraz EN 1363-1. Weryfikację odporności ogniowej stropów w sposób obliczeniowy opisano w części 1. Corresponding author:

Paweł Roszkowski Building Research Institute, Fire Research Department ul. Ksawerów 21; 02-656 Warsaw; POLAND [email protected] phone: 022 56 64 415

86 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 87-95 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Methods and possibilities for conservation of antique wooden floor in Poland – theory and practice

ANNA ROZANSKA1, ANNA POLICINSKA-SERWA2 1 Faculty of Wood Technology, Warsaw University of Life Sciences WULS-SGGW 2 Building Research Institute

Abstract: Antique wooden floors with decorative panel parquets have different preservation condition as well as historic and artistic values. Therefore, renovation and conservation works must be adjusted to a various level of wear and tear of floor or parquet. The conservation may involve only minor repairs with the use of materials and techniques similar to the original ones. In some extreme cases it may also involve restructuring of floor or parquet. The purpose of the research is to analyse the conservation methods of antique wooden floors in Poland on historic and modern examples to recommend the applications of specific materials and repair techniques. The article presents legal grounds for antique floor conservation as well as the analysis of case studies of the best known executions while taking into consideration their effectiveness. It also presents the issue related to the prevention of damage to antique wooden floors on Polish and European markets.

Keywords: antique decorative wooden floor, floor conservation, floor reconstruction

INTRODUCTION Antique wooden floors with decorative panel parquets have different preservation condition as well as historic and artistic values. Therefore, renovation and conservation works must be adjusted to a various level of wear and tear of floor or parquet. The conservation may involve only minor repairs with the use of materials and techniques similar to the original ones. In some extreme cases it may also involve restructuring of floor or parquet. In the first case it is only dictated by the need to make the top layer ready for use (1) or the top layer together with the necessity to repair the structure through replenishing any structure loss without the need to dismantle/relocate it (2). In the second case the necessity to relocate the flooring even with supplementing the damaged parts as well as replacing them with their copies (3). The highest level of interference results from the need and reconstruction of flooring – that takes into account types of structure, pattern and the wood species that are used (4). The concept of floor reconstruction should be coordinated with the plan for restoration of individual rooms, interior colouring as well as the requirements of the conservation officer and expectations of the investor.

SCOPE AND METHODOLOGY The purpose of the research is to analyse the conservation methods of antique timber floors in Poland on historic and modern examples to recommend the applications of specific materials and repair techniques. The article presents legal grounds for antique floor conservation as well as the analysis of case studies of the best known executions while taking into consideration their effectiveness. It also presents the issue related to the prevention of damage to antique timber floors on Polish and European markets.

87 FLOOR RECONSTRUCTION IN THE LIGHT OF REGULATIONS ON MONUMENTS PROTECTION Timber floors are protected according to the Act on protection of listed monuments of 2003 and the only acceptable restriction on this protection is preserving utility values by these floor. Also the theses of the National Programme for the Protection and Care of Historical Monuments which, apart from “conservator officers – office employees, professional conservators – restorers of works of art, conservators – architects, town planners, building restorers, archeologists and researchers” apply also to “the owners and users including clerical regular conservators of historic temples”. The principle “primum non nocere”, the maximum respect for the original substance of the listed monument and its values (material and non- material)”, “the principle of the minimum required interference (refraining from any unnecessary actions)”, “the principle stating that only the parts which have a destructive effect on the original work should be removed” promote a different approach to antique floors replacement, mainly on the part of their owner. The nature of conservation activities must be unblurred and clear and it must be accompanied by descriptive and photographic documentation [Schemat dokumentacji konserwatorskiej 1976, Sękowski, 2003]. The following values listed in the Theses to the National Programme for the Protection and Care of Historical Monuments should be respected: “the principle of legibility and distinctiveness of the interference”, “the principles of the reversibility of methods and materials” and “the principle of executing all the works according to the best practice and to the highest standard”.

CONSERVATION OF FLOORS IN THE LIGHT OF THE CONSTRUCTION REGULATIONS IN FORCE According to the Regulation of the Minister of Culture and National Heritage of 11 January 1994 with amendments, the qualifications required to perform conservation works in listed monuments shall be awarded to people with building licenses (civil engineers and architects) who have several years of experience in immobile monuments as well as graduates of universities specializing in monument conservation. As there are no specialist standards for listed monuments regulated in Poland, conservation works are performed on the basis of the constructions standards in force. As the conservation of wooden floor is connected with the conservation of wooden structures, particular attention should be paid to the phase of diagnostics and the assessment of effectiveness of the suggested repair techniques. It is necessary to follow the adopted guidelines and standards. Conservation activities must be necessary, minimal, reversible and the effectiveness of the techniques used should be proved. Any plans related to conservation activities in the area of wooden structures must be preceded by research activities. Damaged material and structural damage are subject to analysis. Important information about the potential condition of the structure is provided by historical research. Mathematical tests and models are also indispensible [Rozanska et al. 2012b, Rozanska et al. 2012c, Burawska et al. 2012]. The conservation of wooden structures is governed by standards defined by international and national institutions (e.g. ICOMOS International Wood Committee, RILEM TC 215 AST regarding the in-situ assessment of structural timber, EN 1194:1999, Italian UNI-NORMAL WG 20). The basis for conservation of wooden structures involve the “Recommendations for the Analysis, Conservation, and Structural Restoration of Architectural Heritage” of the International Scientific Committee for the Analysis and Restoration of Structures of Architectural Heritage ICOMOS ISCARSAH. According to these recommendations the conservation or restoration (reconstruction) should include several stages of the process: –

88 preventive assessment of the condition of the structure (conservation status), – project planning (initial conservation schedule), – appropriate interference (execution of the conservation and restoration plan), – monitoring of the effectiveness of the interference. The purpose of the assessment of the current conservation status is to learn about the effectiveness of static adaptation of the building and the role of the wooden structure to determine possible conservation plans. According to the above-mentioned standard, it involves performance of the historical analysis, determination of geometrical characteristics, damage characteristics, material characteristics and the analysis of the structure. The historical analysis provides information about the structure and its past (misuse, damage, destruction, alterations). Its tools may involve a dendrochronological analysis, comparative analysis of other nearby historic or contemporary structures in the area of typological differences and similarities. The geometric analysis defines sections of elements, depicts accidental changes of shape and dimension, determines the causes for deformations (related to load and movement or material features) in individual members and the entire structure. The characteristics of damage caused by biotic factors and mechanical damage define the degree of impact of temperature and moisture fluctuations, i.e. the micro-climate inside the structure on its conservation condition. The damage characteristics are determined through visual observation and through drilling in the members to determine the condition of timber. The following are examined: the material (macroscopically, and in case of any doubts, microscopically by collecting a small sample) and mechanical parameters of every wooden members (visually and with non-destructive methods). The moisture content is measured according to EN 13183- 2:2002 by analysing the location of parenchyma cells, growth rate and growth ring inclination [Feio et al. 2005]. The performed examinations result is determination of type, location and scope of damage. The knowledge of the wood species, geometry and member morphology and the nature of damage as well as their location form the basis for assignment of the strength class to the members. Determining preservation condition, historical and geometrical analysis as well as the damage characteristics provide a basis for any interference planning [Turrini, Piazza 1983; Piazza et al. 2009; Crosatti et al. 2009]. The scope of conservation depends on the preservation condition of floors with a tendency to minimize the interference. Reversible methods are used with economical use of materials and that allow to preserve the original structural layers [Turrini, Piazza 1983; Crosatti et al. 2009]. Although fire protection standards do not apply to architectural monuments, it is worth following their recommendation whenever possible.

RECONSTRUCTION OF WOODEN FLOORS IN POLAND Factors affecting necessity to replace floors and the scope of conservation works Antique timber floors have suffered damage for centuries as a result of the natural wood ageing process and as a result of the method of use. The changes in intended use of manor houses and palaces (e.g. Manor House in Dzikowiec or Manor House in Przewrotne) resulted in new internal divisions. Misused buildings collapsed and new owners restored utility values of the monuments by replacing damaged floors, without even documenting it. There is a regular necessity to replace, above all, the architectural woodwork and floors. Such a replacement is very often performed comprehensively, where it is connected with installation of horizontal dampproof and thermal insulation in the building. The replacement happens to be justified by poor preservation condition of the floor resulting from the lack of above-mentioned insulation.

89 However, in Poland the main argument justifying the necessity to replace the wooden elements is fungal attack. Antique panel parquets and their beam support structures are replaced with screeds and mosaic flooring, although strength parameters of antique floors often allow for their further safe use [Rozanska et al. 2011a, Rozanska et al. 2012b, Rozanska et al. 2012c, Andres et al. 2013]. Moreover, new user requirements specified in the construction standards lead to the replacement of antique floor with contemporary solutions, regardless of the pattern and structure. Therefore, following the noble intentions to improve the comfort of use, the only opportunity to save this important part of cultural heritage (the historic values of antique floor that hide in their pattern, structure and product engineering) is squandered. What is more, reconstruction of antique timber floor in Polish museum objects also refers to merely reconstruction of the parquet and it is not practised to reconstruct beam structures which are preserved only in very few buildings. In practice, the reconstructed floors based on the original patterns recorded in drawings or photographs, are installed on a continuous floor base with mineral underlayment and attached with adhesive to it. Such a method seems rational when reconstructing a building where instead of timber floor system the reinforced concrete floor system is installed. But even on a continuous mineral underlayment, as it is the case of contemporary sport floors, it is possible to install beams, formwork and parquet. In the case of sport and entertainment facilities these are floor lathes and in the case of listed monuments – also the panel parquet. When original wooden floor systems are preserved in the listed monuments, it is also worth to take into account the possibility to reconstruct all the layers of the floor. The conservation of wood floor is related to the preservation condition of timber structures [Burawska et al. 2012]. Historic values are thus dominated by overriding aspects of safety which are difficult to assess due to the indicative nature of data, lack of precise assessment of phenomena and discrepancies in the model (e.g. simulated by numbers) and actual conservation status of timber, related to the anisotropic nature of its structure.

Reconstruction of wooden floor in Poland (case study) Post-war reconstruction of timber floors in almost every palace or manor house was carried out by Monuments Conservation Workshops, performing repairs in the 1950s and the 1960s. Due to the utilitarian status of the floor and due to liquidation of the company, materials regarding these reconstructions are scarce and hardly available. Only towards the end of 1960s the Office for Monuments Preservation managed to take care of all the works performed in listed monuments, including the replacement of the parquet and to document them. According to the current conservation practices that apply also to the conservation of antique parquet, the parquet is usually reconstructed since it is believed that in the majority of cases they are not suitable for restoration. When reconstructing the parquet in the historic tenement house in Warsaw, on the basis of the design and technical recommendation of the conservation officer, the old wooden parquet was ripped off and the underlayment was cast. As recommended by the conservation officer, a 15 mm thick OSB plate is attached to the underlayment as additional sound insulation, and then palatial mosaic tiles are attached to it with a pattern based on Baroque parquet in the French residence in Soubise. The members imitating the structural elements were made of oak and the members imitating the fillers were made of light ash or the entire structure was made of oak. The parquet was 10 mm thick with the following slab dimensions: 440 x 440 mm. Before the installation was started, the moisture content in the underlayment was measured with the CM method – 1.8% [Zabytkowe parkiety 2005].

90 A pattern similar to the Versailles pattern by Chapel Parkiet company was used in an old tenement house in Kraków at Plac Mariacki 2, the property of the Parish of the Basilica of St. Mary [Klasyczne piękno drewnianej podłogi 2011]. Also the reconstruction of floor in the historic building dating back to approx. 1870 of Resursa Fabryczna in Żyrardów, involved the attachment of tiles with dimensions of 980 x 980 mm and Versailles pattern to concrete underlayment. The epoxy primer Murexim EP 70 BM was used to attach the mats to the floor. The parquet was attached using a single component flexible adhesive Murexim X-Bond MS- K 511 with long opening time for precise adjustment of tiles [Rewaloryzacja zabytkowej Resursy w Żyrardowie 2011]. The works were performed by “Parkiety Kuczyńskiego” company from Kalisz, holding required conservation licenses. This company started also the reconstruction of parquet in the Fryderyk Chopin European Art Centre in Sanniki [Rewaloryzacja zabytkowej Resursy w Żyrardowie 2011]. Zbigniew Cichocki designed and executed the reconstruction of parquet at the Rehabilitation Centre at the Wiejce Palace [Instytut Rehabilitacji Pałac Wiejce 2003]. There were parquet made of lathes and tiles with a pattern similar to the pattern in the Hallway of the Hunting Palace in Julin. The parquet were attached to the screed (primed with Boba Bonds S520) with Bona Bonds S760 adhesive and painted with: Bona Bonds D-5 primer and Boba Bonds DD-504 finishing paint [Instytut Rehabilitacji Pałac Wiejce 2008]. A similar pattern of tiles, close to that in the original, was used to reconstruct the parquet in the Bronikowski Palace in Żychlin. The oak tiled parquet flooring with dimensions 480 x 480 x 22 mm, connected with loose tongues, attached to the underlayment with the use of polyurethane two-component adhesive ARTELIT PB-89 and protected with two-component paint Silo-pur Finisz firmy Kerakoll [Pałac Bronikowskich w Żychlinie 2010]. In the Ogiński Palace in Siedlce the tiled parquet which were destroyed during the 2nd World War were reconstructed. They were made of solid oak and ash and of the oak mixed with mahogany. Tongue and groove 600 x 600 mm and 575 x 575 mm tiles with the thickness of 22 mm and 400 x 400 mm with the thickness of 32 mm were attached to the underlayment with a two-component adhesive SLC L34 by Keracoll company. They were finished with Euku-ol 1HS oil or Euku-refreshner by Eukula company [Pałac Ogińskich w Siedlcach 2010]. The same finishing agents were used in a private palace in the Mazovia Province. They were used on 471 x 471 mm, 480 x 480 mm, 540 x 540 mm and 600 x 600 mm tiles with the same thickness of 22 mm attached with the polyurethane two-component adhesive Artelit PB-890 as well as rosettes and borders made of oak, maple, nut and merbau [Pałac województwo mazowieckie część I i II 2010]. The reconstruction of parquet in the summer residence of the President of the Republic of Poland, the study of the President in the Sejm, the Hunting palace in Sanssouci in Potsdam, the seat of the Association of Polish Banks, the seat of Eris company in the 18th century palace, several rooms in the Primate’s Palace in Warsaw and many private residences has been made since 1896 by Wytwórnia Posadzek Drzewnych Turant Jacek [Woźniak 2005]. The preserved illustrations and photographs were used as the basis for reconstruction of the set of antique wood floor dating back to the period of reconstruction of the Royal Castle in Warsaw by Stanisław August Poniatowski. It was performed in the years 1972–1983 by Zakłady Wytwórcze Mebli Artystycznych Henryków on the basis of many pre-war illustrations of parquets preserved in the collections of the National Museum and unfinished catalogue of the Rudolf Brothers (well known Warsaw manufacturing plant of parquet from the interwar period). If there were no illustrations, the archival photos were analysed which resulted in poor accuracy of the reconstruction both in terms of pattern and the used species of wood [Lewandowski 2001]. The traditional structure of slabs and methods of their installation was used, but the tiles were installed on screeds and OSB plates [Zamkowe podłogi 1989] instead of beam structures.

91 In Poland, even the floor reconstruction in the buildings renovated under supervision of the Conservation Officer are rarely made on the basis of the preserved original patterns. The best example here are the lost floorings from the Manor House in Hyżne in the southeastern Poland which were described by Taichman in 1994 [Taichman 1994] or the floors removed in 2010 from the floor of the Manor House in Niwiska. During major renovations aimed at adaptation of the listed monuments to a new function, first of all the historic floors are removed, e.g. Tyszkiewicz Palace in Werynia (adapted for the needs of the Rzeszów University), occasionally leaving several slabs as documentation (e.g. Estate Outbuilding in Kolbuszowa which was adapted for the seat of the Folk Culture Museum). New private owners of neglected manor houses, instead of conservation of the preserved timber floorings prefer to replace them with more durable and more fashionable solutions (e.g. the Manor house in Kombornia adapted for leisure complex). However, there are some exceptions – the parquet from Kombornia were reinstalled in the Manor House in Kopytowe, where the original floors were not preserved. Very often the investors themselves are the authors of the reconstruction concepts. The floor construction at the Manor House in Witkowice was performed by a parquet company according to its own patterns inspired by partially preserved original patterns of the rosette and tiles. As requested by the owners, the reconstruction was adapted to the nature of the building and it was based on the patterns of simpler parquet of the nearby Łańcut Castle. Whenever justified, the reconstructions use exotic wood species with better physical properties (shrinkage factor) and strength properties such as for example avodire instead of the original ash used in the Royal Castle in Warsaw. [Kozakiewicz, Szkarłat 2004]. Also for the newly designed, stylized parquets it is recommended to use simple and clear geometric patterns based on up to two wood species – exotic species often unprecedented in historic parquet, such as iroko mixed with oak [Kuczyńska-Cichocka 1999b]. Such a method of reconstruction was adopted for example in the rooms of the Bank Staropolski in Poznań, the Palace in Ciążeń, Neoclassical Gorzno Palace and the Palace in Bytyń [Kuczyńska-Cichocka 1999a]. At present the main conservation problem of antique timber floors are the parquets in listed monuments owned by private investors who prioritize full restoration of utility values within the meaning of the contemporary building standards. For obvious reasons the antique parquet does not meet these requirements (no damp insulation, thermal insulation, etc.), therefore it is replaced with new mosaic tiles or lathes installed on a continuous screed. The parquet magazines (e.g. Parkieciarz) provide many examples of “reconstructions” performed by parquet companies in private palaces and manor houses. The investors try to restore the 19th century patterns; however, also due to limited range of products available on the market, they choose inappropriate patterns. Most of these structures have no reference to the patterns and structures used in the original, without taking into consideration the degree of representativeness of the monument or region of the country, but they repeat a popular type of mosaic parquet with patterns based on Henryków manufacture for the Royal Castle in Warsaw. This kind of approach can be seen in the Palace in Olszanica, located in southeastern Poland.

DAMAGE PREVENTION REGARDING ANTIQUE TIMBER FLOOR A common practice in protection of antique timber flooring is the use of shoe protectors or separation and covering of circulation paths with carpets. In both cases the sand going between the parquet and the textile causes its abrasion and larger particles cause scratches and dents. The use of carpets also results in differences in colours between the covered and not covered sections of the parquet. Therefore, an effective way to isolate the parquet from the pedestrians is being searched for. A method used for example in the castles in Potsdam is a

92 transparent bridge on the steel structure above the stone flooring [Vondung 2001]. However; since the gap between the flooring and the pane is too small, water condensation increases the moisture content and discolours the parquet. The problem is also the weight of the metal structure which prevents the use of this type of solutions with beam floor systems. An alternative solution is to cover the entire room with glass plates resting on point supports to reduce the weight of the structure and distribute it evenly over a larger surface of the floor [Vondung 2001]. Unfortunately, all the suggested treatments heavily interfere with the historic substance, and particularly in its aesthetic reception.

SUMMARY The conservation of antique timber floor is a complex, interdisciplinary issue and it requires special attention and normative regulations [Tajchman 1996; Kurpik, Ważny 2004]. Since the conservation of antique timber floor is connected with the preservation condition of wooden structures and it refers to the safety issue, it is possible to reconstruct the floors if it is justified. The reconstruction of the floor based on the in-depth knowledge of the structure of antique floor, may be the source of knowledge about these structures provided to the next generations which complies with the valid conservation doctrine and the idea of the protection of the national heritage. Reconstruction of timber floors implies using materials similar to the original ones which, however, meet high requirements of contemporary building standards. According to the idea of preservation of the historic substance, in the floor reconstruction in listed monuments it is worth to consider the possibility of relocation of the parquets from other monuments, in particular if the reconstruction is made for the institution with a specific cultural mission. Moving away from traditional technological solutions, that is currently observed, is related to the fact that the construction of the floor with the beam structure and with panel parquet is very labourious as well as time consuming. I also requires using good quality timber which has direct consequences on the prices.

REFERENCES 1. ANDRES B, RÓŻAŃSKA A., SANDAK J., 2013: Influence of Fungi on the State of Preservation and on the Usage Prospects of Antique Wooden Parquets from Manor Houses in South-Eastern Poland, 2nd International Conference on Structural Health Assessment of Timber Structures (SHATIS’13), 4-6 September 2013, Trento, Italy. 2. BURAWSKA I., RÓŻAŃSKA A., JANKOWSKA A., BEER P., 2012: Technical state analysis and reinforcement project of antique wooden flooring with joist structure, Proceeding of the 8th International Conference on Structural Analysis of Historical Construction SAHC 2012, 15-17 October 2012, Wrocław Poland, Wrocław, 1992-1997. 3. CROSATTI A., PIAZZA M., TOMASI R., ANGELI A., 2009: Refurbishment of traditional timber floor with inclined screw connectors, [w:] Proc. Prohitech 09, Protection of Historical Buildings 1st Interanational Conference. Rome, June 1st-24th, Rome. 4. FEIO A.O., MACHADO J.S., LOURENCO P.B., 2005: Parallel to the Grain Behavior and NDT Correlations for Chestnut Wood (Castanea Sativa Mill.), Conservation of Historic Wooden Structures, Florence, 294-303. 5. Instytut Rehabilitacji Pałac Wiejce, 2003: Podłoga 9: 44-45. 6. Instytut Rehabilitacji Pałac Wiejce, 2008: Parkieciarz 5: 30-32. 7. Klasyczne piękno drewnianej podłogi, 2011: Podłoga 4: 18-19.

93 8. KOZAKIEWICZ P., SZKARŁAT D., 2004: Avodire – jasne drewno o bogatym rysunku, Podłoga 4: 25-27. 9. KUCZYŃSKA-CICHOCKA B., 1999a: Parkiety zabytkowe - rozważania konserwatorskie, Podłoga 8: 23-25. 10. KUCZYŃSKA-CICHOCKA B., 1999b: Rekonstrukcja parkietów taflowych, Podłoga 10: 17-21. 11. KURPIK W., WAŻNY J., 2004: Konserwacja drewna zabytkowego w Polsce - historia i stan badań, w: Ochrona drewna. Mat. z XXII Sympozjum, Warszawa, 5-24. 12. LEWANDOWSKI H., 2001: Henrykowskie posadzki w Warszawskim Zamku Królewskim 1972-1983, w: Restytucja Zamku Królewskiego w Warszawie, praca zbiorowa, Wydawnictwo Projekt, Warszawa, 170-185. 13. Pałac Bronikowskich w Żychlinie, 2010: Parkieciarz 3: 35-38. 14. Pałac Ogińskich Siedlce, 2010, Parkieciarz 1: 33-37. 15. Pałac województwo mazowieckie część I, 2010: Parkiecierz 4: 37-39. 16. Pałac województwo mazowieckie część II, 2010: Parkiecierz 5: 37-39. 17. PIAZZA M., RIGGIO M., TOMASI R., ANGELI A., 2009: Etapy działania i kryteria w odnawianiu podłóg drewnianych w Pałacu Belasi (Trydent we Włoszech), Wiadomości Konserwatorskie 26: 289-299. 18. Rewaloryzacja zabytkowej Resursy w Żyrardowie, 2011: Podłoga 6, 16-17. 19. RÓŻAŃSKA A., TOMUSIAK A., BEER P., 2011c: Influence of Climate on Surface Quality of Antique Wooden Flooring in Manor House, Proceeding of the 20th International Wood Machining Seminar, Skellefte, Sweden June 7-10, Slelleftea, 208- 217. 20. RÓŻAŃSKA A., BEER P., WIECHA A., 2012ba: Influence of the physical properties of the wood of antique parquets on the morphological characteristics of their surface, Prezentacja na 2012 IUFRO Conference division 5 forest products, lipiec 2012, Lizbona Portugalia. 21. RÓŻAŃSKA A., BURAWSKA I., BEER P., 2012b: Function of joint in the structure of antique wooden panel parquets on the example of parquets from Przewrotne manor house, Annals of Warsaw University of Life Sciences- SGGW 80: 16-21. 22. RÓŻAŃSKA A., BURAWSKA I., POLICIŃSKA-SERWA A., KORYCIŃSKI W., MAZUREK A., BEER P., SWACZYNA I., 2012c: Study of antique wooden floor elements of chosen buildings from south-eastern Poland, Proceeding of the 8th International Conference on Structural Analysis of Historical Construction SAHC 2012, 15-17 October 2012, Wrocław Polska, Wrocław, 905-913. 23. Schemat dokumentacji konserwatorskiej zabytków ruchomych, „Biblioteka Muzealnictwa i Ochrony Zabytków”, Seria B, t. LXXII, Warszawa 1976. 24. SĘKOWSKI J., 2003: Konserwacja mebli zabytkowych, Semper, Warszawa. 25. TAJCHMAN J., 1996: Wartościowe elementy drewniane występujące w zabytkach architektury wymagające szczególnej ochrony przeciwpożarowej, Ochrona przeciwpożarowa obiektów zabytkowych, Materiały Konferencji II Międzynarodowego Sympozjum, Kraków 17-21 X 1996, Poznań. 26. VONDUNG M., 2001: Historia parkietu cz. 5, Podłoga 10: 40-42. 27. WOŹNIAK A., 2005: Charakterystyka posadzek drewnianych w Muzeum Zamoyskich w Kozłowce, praca magisterska, Wydział Technologii Drewna SGGW wykonana pod kierunkiem prof.dr hab.Ireny Swaczyny, Warszawa. 28. Zabytkowe parkiety, 2005: Podłoga 10: 35-36. 29. Zamkowe podłogi, 1989: Spotkania z Zabytkami: 34-36.

94 Streszczenie: Metody i możliwości konserwacji historycznych podłóg drewnianych w Polsce - teoria i praktyka. Zabytkowe podłogi z dekoracyjnymi posadzkami taflowymi różnią się stanem swojego zachowania oraz wartościami historycznymi i artystycznymi. Dlatego prace renowacyjne lub konserwatorskie dostosowane być muszą do zróżnicowanego stopnia zużycia podłogi lub posadzki. Ingerencja konserwatorska może oznaczać jedynie drobne naprawy, z zastosowaniem materiałów i technik zbliżonych do oryginalnych. Może także w ekstremalnych przypadkach oznaczać rekonstrukcję podłogi lub posadzki. Celem badań jest analiza metodyki konserwacji zabytkowych podłóg drewnianych w Polsce na przykładach historycznych i współczesnych w celu rekomendacji zastosowań określonych materiałów i technik naprawczych. W artykule przedstawiono podstawy prawne konserwacji podłóg zabytkowych oraz analizę przypadków (case study) najbardziej znanych realizacji, z uwzględnieniem ich efektywności. Opisano także problematykę profilaktyki uszkodzeń zabytkowych posadzek drewnianych na przykładach polskich i europejskich.

Słowa kluczowe: zabytkowe drewniane podłogi ozdobne, konserwacja podłóg, rekonstrukcja podłóg

Corresponding author:

Anna Rozanska Department of Technology and Entrepreneurship in Wood Industry, Faculty of Wood Technology, Warsaw University of Life Sciences – SGGW, ul. Nowoursynowska 159, 02-776 Warsaw, Poland e-mail: [email protected]

Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 96-101 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Experimental testing of a spatial furniture joint

DANIEL RUMAN, VLADIMÍR ZÁBORSKÝ, VLASTIMIL BORŮVKA, MILAN GAFF Department of wood processing Faculty of forestry and wood sciences, University of Czech University of Life Sciences in Prague, Kamýcká 1176, Praha 6 - Suchdol, 16521 Czech Republic;

Abstract: Experimental testing of a spatial furniture joint. This article deals with experimental testing of a spatial corner joint with a non-continuous, interlocking tapered tenon with a thickness of 8 mm. This type of joint was glued with polyurethane (PUR) glue. The glue was applied to the tenon as well as the mortise, according to the manufacturer's technical data sheet. This research focused primarily on the verification of the pressure test performed on a universal testing machine. After the accuracy of this method is verified, we will experimentally test other types of joints of different sizes, shapes and two types of furniture adhesives, in future research. Beechwood (Fagus sylvatica L.) with an equilibrium moisture content of 8% was used to create the furniture joint. We evaluated the elastic stiffness of the tested furniture joint in a tensile test from the stress-strain diagram.

Keywords: furniture joint, elastic stiffness of the joint, load capacity of joint, tenon, mortise

INTRODUCTION Spatial joining of construction elements with a mortise and tenon is one of the most widely used methods in the furniture-making industry. This joint is usually glued, and the greatest strength is achieved when the glue is applied to both the mortise and the tenon (Terrie, N 2009). An important condition for creating the joint is ensuring a minimum dimensional tolerance. Most authors investigate the load-bearing capacity, joint strength and deformation characteristics (Eckelman, C., A. 2003). The most dangerous cases of joint loading is the bending moment in its angular plane (Erdil et al. 2005 and Prekrat and Španic 2009 and Uysal et al. (2015). In his article, Smardzewski (2002) dealt with the sizing of tenons and mortises that were glued. He designed a comprehensive static analysis of the glued joint using tenons and mortises. His research has shown that the bending moment force depends on the length of the tenon. Prekrat and Španic (2009) also tried to determine the best type of corner joint with a tenon through scientific methods. They compared three types of corner joints (both round tenons, a tenon with a combination of pins, and a round tenon with a combination of pins and a steel cylinder and screw), which were subjected to bending moment. The third combination had the highest load-bearing capacity, and the second combination had the lowest loadbearing capacity. The purpose of this preliminary research is to test a spatial furniture joint made from beechwood in a tensile test (Fagus sylvatica L.)

MATERIALS Beechwood was used to create the test samples (Fagus sylvatica L.) The 52 mm beach planks were dried to an equilibrium moisture content of 8% in climatic chamber APT Line II (Binder; Germany) at a relative humidity of 40% and temperature of 20°. This moisture content is the standard moisture content for furniture components (ČSN 91 0001) (1998). Dimension timber was cut from the planks, the shape and design of which were formed on

CNC machines. Figures 1 and 2 show a detailed drawing of the joint, consisting of a stile with mortises and a rail with a non-continuous, interlocking, oval tapered tenon with an 8 mm thickness, and holes with a diameter of 10.5 mm for attaching to the universal testing machine. Polyurethane glue NEOPUR 2238R (AGGLUE; Slovakia) was applied to the mortises and tenons of the joint pursuant to the technical data sheet. The assembled furniture joint (ČSN 49 0000 1998) was installed and clamped using table clamps. Figure 3 shows the pressure testing of samples, which was carried out using a universal testing machine UTS 50 (Germany). 10 samples were tested

Figure 1. Technical drawing of the structural joint

Figure 2. 3D depiction of rail

Figure 3 shows the mounting of the test sample under compressive stress, using the testing device UTS 50 (Germany). We tested 10 test samples in order to verify the test method.

Figure 3. Experimental testing of a structural joint

RESULTS

Table 1. Table of average data type of type of force force distance distance change in change Elastic loading adhesi 10% in 40% in 10% in mm 40% in moment in stiffness ve N N mm in Nm angle in in ° Nm/rad pressure pur 55,20 220,90 0,57 2,56 21,91 0,86 1464

The elastic stiffness was evaluated according to the equation C=M/y, where M represents the change in moment (Nm) and y represents the change in angle in °.

Figure 4 shows a stress-strain diagram of the preliminary testing of the spatial joint bonded with PUR adhesive.

Figure 4. Stress-strain diagram

The average density of samples calculated at 12% is 708 kg/m3. This value is similar to that of authors Požgajet al. (1993), who reported an average beechwood density of (Fagus sylvatica L.) 712 kg/m3. Wagenführ (2000) reports a beechwood (Fagus sylvatica L.) density of 720 kg/m3 at a 12% moisture content.

Figure 5 shows the structural joint sample after compressive loading. There is no visible damage to the stile or rails, but one rail was partly pushed away from the stile where the tenon was attached.

Figure 5. Structural joint after loading

The described experiment was aimed at verifying the compressive test method of a spatial furniture joint with a non-continuous, interlocking tenon with a thickness of 8 mm. The tested method was proven to be suitable for selected types of spatial structural joints, and we will use it to experimentally test other structural joints of different, types, sizes and with different adhesives.

REFERENCES

1. ČSN 91 0001. (2007). “Furniture -Technical requirements,” Czech Office for Standards, Metrology and Testing, Prague, Czech Republic. (in Czech) 2. WAGENFÜHR, R. (2000). Holzatlas, 5th Edition, Fachbuchverlag, Leipzig, Germany (in German), 707 p. 3. ČSN 49 0000. (1998). “Terminology in woodworking industry. General terms and wood properties, Metrology and Testing, Prague, Czech Republic. (in Czech). 4. Požgaj, A., Chovanec, D., Kurjatko, S., Babiak, M. (1993). Štruktúra a Vlastnosti Dreva [Structure and Properties of Wood], Príroda a. s., Bratislava, Slovakia (in Slovak), 486 p. 5. ISO 13061-1 (2014). “Wood-determination of moisture content for physical and mechanical tests,” International Organization for Standardization, Geneva, Switzerland. 6. TERRIE, N. 2009: Joint Book: The Complete Guide to Wood Joinery, Chartwell Books, 192 p.

100

Streszczenie: Badania wytrzymałościowe połączeń przestrzennych. Badno połączenia czopowe z drewna buka łączone na klej poliuretanowy. Zbadano moduł sprężystości i wytrzymałość, określono wpływ wymiaru łącza na badane parametry.

Corresponding author:

Name Surname, Daniel Ruman street address, Novohradská 996/8 zip code, town, country 99 001 Veľký Krtíš email: [email protected] phone: 00421 902 977 071

101 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 102-106 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Aluminium glazed partitions with timber insulation inserts – fire resistance tests results depending on the type of used wood

BARTŁOMIEJ SĘDŁAK, DANIEL IZYDORCZYK, PAWEŁ SULIK Fire Research Department of Building Research Institute

Abstract: This paper discusses the main problems related to the fire resistance of aluminium glazed partitions with timber insulation inserts, including the tests methodology and way of classification of this type of elements. Moreover, the paper presents the comparison of fire resistance test results of glazed partition with timber insulation inserts test specimens, depending on the type of wood used as an insulation insert.

Keywords: glazed partition, aluminium profile, timber insulation insert, fire resistance

INTRODUCTION Partition walls plays a key role in fulfilling the fire safety requirements for the buildings. They shall be designed and constructed in such way that in case of fire they will limit the spread of fire and smoke in the building, allow the evacuation of users and ensure the safety of rescue team. Usually they are made as non-transparent constructions made of monolithic cast on side elements or masonry [1], as well as light constructions made of gypsum plasterboards [2], [3] or special wooden boards [4]. In the buildings can also be found non-transparent walls made of glass blocks [5] or glazed with special fire resistance glass panes [6], [7] placed in timber [8], [9], steel [10], [11] or aluminium [12]–[15] profiles as well as those with structural glazing [16]. Because of the subject only the partitions made of aluminium profile will be discussed in this paper. Aluminium glazed partitions with a specific fire resistance class have a frame (mullion – transom) structure in which the areas between the aluminium profiles are filled with special fire resistant glass panes – monolithic [17] or layered (with intumescent gel) [6], [7]. The most commonly used in practice are three-chamber profiles made of two aluminium parts connected by means of thermal separators (eg. made of polyamide reinforced with glass fiber) [18]. In order to ensure the insulation and reduce the adverse impact of thermal effects, chambers of the profiles are filled with the insulation inserts (eg. made of plasterboard, cement silicate or calcium silicate). This paper presents the test results for untypical structural solution – glazed partitions made of aluminium profiles without the thermal separator and filled with timber insulation inserts made of pine and beech plywood.

FIRE RESISTANCE TESTS Fire resistance class of glazed partitions cannot be assessed or calculated on the basis of its project. The only way to determine the real fire resistance class is to perform the fire resistance test of its fully representative specimen. If the partition wall has a symmetrical cross-section, then it is sufficient to test it only from one side. In other case, it is necessary to verified the element from both sides in order to get fully assessment. To reflect the conditions of fire inside the building the test specimen is placed in the opening of special furnace and heated in accordance with the standard temperature-time curve defined by the equation below:

= 345 8 + 1 + 20

102 During the fire resistance test of glazed partitions the effectiveness of the following performance criteria can be verified: integrity (E), insulation (I) and radiation (W). Integrity is the ability of glazed partition test specimen, when exposed to fire on one side, to prevent the passage through it of hot gases and flames and to prevent the occurrence of flames on the unexposed side. Insulation is the ability of glazed partition test specimen when exposed to fire on one side, to restrict the temperature rise of the unexposed face to below specified levels. Radiation is the ability of a glazed partition test specimen, when exposed to fire on one side, to prevent the passage of the fire, due to the transfer of significant heat through the element or through its unexposed surface to the adjacent materials. Moreover, during the test deflection of the test specimen shall be measured although there are no performance criteria associated with it. The deflection of the test specimen may be important in determining the direct and / or extended field of application of the test result [19]–[21]. Way of the verification of each criterion and more valuable information about the testing of glazed partitions are presented in [10], [11], [22]–[27].

FIRE RESISTANCE CLASSIFICATION

Classification of glazed partition fire resistance is prepared basing on the test results presented in test report. According to the European Union provisions the fire resistance test shall be performed in accordance with EN 1364-1:2015 and the classification shall be compiled in accordance with the requirements given in EN 13501-2:2016. Classification standard defines fire resistance classes shown in table 1. Table 1 Fire resistance classes (E – integrity, I – insulation, W – radiation) [8] E 20 30 60 90 120 EI 15 20 30 45 60 90 120 180 240 EW 20 30 60 90 120

TEST SPECIMENS AND RESULTS

The comparison was made for two test specimens with the same transom – mullion structure and dimensions of 3,6 x 3,6 m. The specimens were made of symmetrical aluminium profiles, structural depth of 115 mm filled with insulation inserts made of pine plywood, density of 500 kg/m3 (specimen No. 1) and beech plywood, density of 700 kg/m3 (specimen No. 2). Both of the used insulation inserts were impregnated with the same special paint. The areas between the profiles were filled with glazing made of special fire resistance glass pane (placed on the fire side) and toughened glass pane (placed on the opposite side), except of the one area which was filled with opaque panel made of chipboard, mineral wool, plasterboard and steel sheet. Test results comparison made for the average temperature rises on the transoms and mullions is presented in fig. 1.

103

a) b)

Figure 1 Comparison of average temperature rise on the unexposed surface of tested specimens depending on the type of used wood in insulation inserts – a) temperature on the mullion profiles , b) temperature on the transom profiles (Source: Fire Research Department of ITB archives) The test of the element with pine plywood insulation inserts lasted 39 minutes and was finished due to the failure of one of the used glass panes. The second test (with beech plywood insulation inserts) lasted 72 minutes and was finished due to the sustained flaming above the area filled with opaque panel. In both tests the maximum recorded deflection was on the one of inside mullions. In case of specimen No. 1 the maximum deflection in 30th minute of the test was 24 mm in direction outside the furnace and in case of the specimen No. 2 the maximum deflection in the same time and place was 16 mm in direction outside the furnace.

CONCLUSIONS Analyzing the test results presented in fig. 3 it can be observed that the aluminium glazed partitions with beech plywood insulation inserts behave much better in the fire conditions. The greatest density caused that the wall was more stiffer and the deflection of the element was much lower. It could be one of the factors that contributed to it that the test No. 2 could be conducted for above 30 minutes longer then test No. 1. Moreover it is worth to notice that the beech plywood was a better insulator – the temperature rises recorded on the wall with those type of inserts were significantly lower, what is clearly visible in figure 2.

Figure 2 Difference between the average temperature rise on the unexposed surface of glazed partition wall with beech plywood insulation inserts and pine plywood insulation inserts

104 REFERENCES

[1] P. Sulik and B. Sędłak, “Ochrona przeciwpożarowa w przegrodach wewnętrznych,” Izolacje, vol. 20, no. 9, pp. 30–34, 2015. [2] B. Wróblewski and A. Borowy, “Płyty gipsowo-kartonowe – odporność ogniowa ścian nienośnych,” Izolacje, vol. 10, 2010. [3] G. Thomas, “Thermal properties of gypsum plasterboard at high temperatures,” Fire Mater., vol. 26, no. 1, pp. 37–45, Jan. 2002. [4] P. Roszkowski, P. Sulik, and B. Sędłak, “Fire resistance of timber stud walls,” Ann. Warsaw Univ. Life Sci. - SGGW For. Wood Technol., vol. 92, pp. 368–372, 2015. [5] B. Sędłak, “Ściany działowe z pustaków szklanych – badania oraz klasyfikacja w zakresie odporności ogniowej,” ŚWIAT SZKŁA, vol. 19, no. 1, pp. 30–33, 2014. [6] K. Zieliński, “Szkło ogniochronne,” ŚWIAT SZKŁA, vol. 1, pp. 9–11, 2008. [7] Z. Laskowska and A. Borowy, “Szyby w elementach o określonej odporności ogniowej,” ŚWIAT SZKŁA, vol. 20, no. 12, pp. 10–15, 2015. [8] B. Sędłak, D. Izydorczyk, and P. Sulik, “Fire Resistance of timber glazed partitions,” Ann. Warsaw Univ. Life Sci. - SGGW For. Wood Technol., vol. 85, pp. 221–225, 2014. [9] P. Sulik and B. Sędłak, “Odporność ogniowa drewnianych przeszklonych ścian działowych,” ŚWIAT SZKŁA, vol. 20, no. 3, pp. 43–48, 56, 2015. [10] P. Sulik and B. Sędłak, “Odporność ogniowa pionowych przegród przeszklonych. Część 1,” ŚWIAT SZKŁA, vol. 20, no. 7–8, pp. 37–38,40,42–43, 2015. [11] B. Sędłak, “Bezpieczeństwo pożarowe przeszklonych ścian działowych,” ŚWIAT SZKŁA, vol. 20, no. 5, pp. 34–40, 2015. [12] B. Sędłak, “Systemy przegród aluminiowo szklanych o określonej klasie odporności ogniowej,” ŚWIAT SZKŁA, vol. 18, no. 10, pp. 30–33,41, 2013. [13] B. Sędłak, P. Sulik, and P. Roszkowski, “Fire resistance tests of aluminium glazed partitions with timber insulation inserts,” Ann. Warsaw Univ. Life Sci. - SGGW For. Wood Technol., vol. 92, pp. 395–398, 2015. [14] B. Sędłak, P. Sulik, and J. Kinowski, “Wymagania i rozwiązania techniczne systemów pionowych przegród przeszklonych o określonej klasie odporności ogniowej,” BiTP, vol. 42, no. 2, pp. 167–171, 2016. [15] B. Sędłak, J. Kinowski, D. Izydorczyk, and P. Sulik, “FIRE RESISTANCE TESTS OF ALUMINIUM GLAZED PARTITIONS, Results comparison,” Appl. Struct. Fire Eng., Jan. 2016. [16] B. Sędłak, “Bezszprosowe szklane ściany działowe o określonej klasie odporności ogniowej,” ŚWIAT SZKŁA, vol. 19, no. 11, p. 24,26,28,30, 2014. [17] Y. Zhan, Z. Xia, W. Xin, and L. Hai-lun, “Application and Integrity Evaluation of Monolithic Fire-resistant Glass,” Procedia Eng., vol. 11, pp. 603–607, 2011. [18] K. Kuczyński, “Kształtowniki metalowe z przekładką termiczną,” Mater. Bud., vol. 8, pp. 38–39, 2010. [19] B. Sędłak and P. Roszkowski, “Klasyfikacja w zakresie odporności ogniowej przeszklonych ścian działowych,” ŚWIAT SZKŁA, vol. 17, no. 7–8, pp. 54–59, 2012. [20] Z. Laskowska and A. Borowy, “Rozszerzone zastosowanie wyników badań odporności ogniowej ścian działowych przeszklonych wg PN-EN 15254-4,” Mater. Bud., vol. 7, pp. 62–64, 2012. [21] J. Kinowski, B. Sędłak, P. Sulik, and D. Izydorczyk, “FIRE RESISTANCE GLAZED CONSTRUCTIONS CLASSIFICATION, Changes in the field of application,” Appl. Struct. Fire Eng., Jan. 2016.

105 [22] P. Roszkowski and B. Sędłak, “Metodyka badań odporności ogniowej przeszklonych ścian działowych,” ŚWIAT SZKŁA, vol. 16, no. 9, pp. 59–64, 2011. [23] B. Sędłak, “Badania odporności ogniowej przeszklonych ścian działowych,” ŚWIAT SZKŁA, vol. 19, no. 2, pp. 30–33, 2014. [24] P. Sulik and B. Sędłak, “Odporność ogniowa pionowych przegród przeszklonych. Część 2,” ŚWIAT SZKŁA, vol. 20, no. 9, pp. 31–32,34–35, 2015. [25] B. Sędłak and P. Sulik, “Odporność ogniowa pionowych elementów przeszklonych,” Szkło i Ceram., vol. 66, no. 5, pp. 8–10, 2015. [26] J. Kinowski, P. Sulik, and B. Sędłak, “Badania i klasyfikacja systemów pionowych przegród przeszklonych o określonej klasie odporności ogniowej,” BiTP, vol. 42, no. 2, pp. 135–140, 2016. [27] B. Sędłak, “Wymagania z zakresu nienośnych przegród przeciwpożarowych - przeszklone ściany osłonowe i działowe, drzwi i bramy,” in Budynek wielofunkcyjny z częścią usługowo-handlową i garażem podziemnym - w aspekcie projektowania, wykonawstwa i odbioru przez PSP: Materiały pomocnicze do wykładów, Warszawa: Grażyna Grzymkowska-Gałka ARCHMEDIA, 2016, pp. 43–62.

Streszczenie: Aluminiowo-szklane ściany działowe z drewnianymi wkładami izolacyjnymi – wyniki badań odporności ogniowej w zależności od zastosowanego rodzaju drewna. W artykule omówione zostały główne aspekty związane z odpornością ogniową aluminiowo- szklanych ścian działowych z drewnianymi wkładami izolacyjnymi, w tym procedura badania oraz sposób klasyfikacji elementów tego typu. Ponadto w artykule przedstawione zostało porównanie wyników badań elementów próbnych aluminiowo-szklanych ścian działowych z drewnianymi wkładami izolacyjnymi w zależności od rodzaju drewna zastosowanego jako wkład izolacyjny.

Corresponding author:

Bartłomiej Sędłak, 21, Ksawerów St. 02-656, Warsaw, Poland email: [email protected] phone: +48 609 770 198

106 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 107-114 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Methods and possibilities for conservation of antique wooden floor in the light of current construction standards

ANNA POLICINSKA-SERWA1, ANNA ROZANSKA2 1 Building Research Institute 2 Faculty of Wood Technology, Warsaw University of Life Sciences WULS-SGGW

Abstract: This study presents a view on legal conditions of reconstruction and renovation of timber floor – i.e. tasks involving reconstruction of the damaged building to protect it against total destruction, with the use of any measures to preserve historical values of the building, protect the original condition together with the possibility to supplement the architectural artifacts and renovation – the purpose of which is to renovate the damaged listed monument by reconstructing the architectural artifacts.

Keywords: antique decorative wooden floor, floor conservation, floor renovation and reconstruction

SCOPE AND METHODS OF RESEARCH The act on the protection of monuments [Dz. U.2003 / Journal of Laws of 2003] uses several terms referring to the principles of respecting and maintenance of the historic substance – defining the scope of the works, these are: conservation, restoration, renovation and reconstruction. This study presents a view on legal conditions of reconstruction and renovation of timber floor – i.e. tasks involving reconstruction of the damaged building to protect it against total destruction, with the use of any measures to preserve historical values of the building, protect the original condition together with the possibility to supplement the architectural artifacts and renovation – the purpose of which is to renovate the damaged listed monument by reconstructing the architectural artifacts.

VALUES OF ANTIQUE FLOOR In the case of timber floor a decision concerning the selection of conservation measure is extremely difficult since, apart from cultural values of the listed monument, it is also necessary to take into account the functional and economic aspects, where the above- mentioned aspects overlap with specific features of the material [Vondung 2001]. When selecting the work method the basic issue to consider is the preservation condition of the timber – a degree of its deterioration, moisture content increase, drying out, that is technical and aesthetic changes [Kuczyńska-Cichocka 1999a]. The specific nature of antique timber floors – that rumble with every step, squeak, have chips or uneven surface and discolouration with a different degree of intensity – is also significant for the investors. The antique timber floors, similarly to an antique piece of furniture [Krawczyk 2004 and 2006] have historic value [Frodl 1966, Pomian 1996]. Its structure is the proof of development of joinery, structural and construction techniques. The quality of the parquet demonstrates the class of the workmanship, the pattern is the sign of the taste of a given era and it shows the reception of European art. The antique parquet shows the artistic and scientific values, the artistic quality and its impact, it collects information about development of the forms of style, era, aesthetic trends as well as the owners – their profession, hobbies and tastes. The parquets transfer traces of the past of monuments from which they come: e.g. changes in the interior design, renovations and alteration after changes of the owners or their social status. The parquet is the product from the borderline between the history of art and craftsmanship, related to the everyday life. When making a decision related to the

107 preservation or replacement of the floor it is necessary to take into account the preferences of the future user. The parquet must be connected with the type of the interior decor – the degree of its representativeness and it must take into account the comfort related expectations. The main objective of the conservation officer is to protect the antique wood floors to protect their physical integrity as a historic document. The works include protection and preservation of the substance of the listed monument and inhibition of destructive processes. Before any decision on the conservation is made it is necessary to make a diagnosis as accurately as possible. “Preservation of the original condition” should limit the conservation interference only to necessary repairs while the concept of “antiquity” allows to preserve some imperfections of the floors for the sake of higher causes. In the conservation doctrine since mid 19th century more and more attention has been paid to the authenticity of the material [Krawczyk 2006] while in the second half of the 20th century the thesis was adapted that “the historic substance contains the authenticity of the listed monument” [Kurzątkowski 1998]. When making a decision on the replacement, not only the pattern of the parquet should be restored (the adopted practice), but all the structural layers of the floors according to the value of completeness and authenticity of elements for the “consistence of the integral artistic impression” [Frodl 1966].

TECHNOLOGICAL PROBLEMS OF THE RECONSTRUCTION The attempts to relocate the antique floors to new buildings are faced with serious technological problems related to a different type of the underlayment on which they are installed. In architectural monuments the floor had the beam structure with the parquet attached to the beams usually with the use of nails, and in the new ones there are screeds. The attempts to attach the historic tiles to the underlayment are faced with significant technical difficulties, mainly due to dimensions of the tiles combined with wood properties. Rigid attachment of the tiles limits, or even prevents, free changes of tile dimensions and deformations on several levels. Therefore, the selection of the type of the underlayment should be carefully considered. Moreover, the structural system and the floor itself – installed these days, must meet the requirements of safety and suitability for use required by current legal acts and technical regulations.

REGULATIONS AND RULES GOVERNING THE USE OF CONSTRUCTION MATERIALS IN THE WORKS Conservation material characteristics The materials for conservation purposes should be characterized by visual properties that are as similar to the original as possible. However, the product subject to the treatments – if it is not provided for decorative purpose only, must, or at least should meet the requirements that guarantee the durability of performance and in particular those related to the safety of use according to the requirements of the act on construction products [Dz. U.2004 / Journal of Laws of 2004]. In all the works related to the performance of construction works – and they include also the activities indicated in the article, it is basically possible to use products that are currently approved for use. In exceptional situations, in particular in the case of traditional or historic solutions and in the case of special newly introduced products, it is possible to use the clause of individual admittance while taking into account the individual, usually expensive verification of their properties. The group to which the requirements formally do not apply involve products for gluing the flooring to the underlayment, fillers, varnishes, waxes and oiled waxes. Requirements for the underlayment and the parquet members In Europe, many years of tests performed by research centres, professional bodies and opinion formers resulted in universalized requirements also in relation to timber floors and

108 materials used to construct them, e.g. the manufacturing of floor products is governed by the requirements of CPR 305/2011 (EU Regulation) which oblige to use the harmonized European standards and related European standards for the product. The materials that can be used for floor need to meet the requirements of EN 14342 standard and related standards. The related standards refer – among other things – to the detailed properties used to identify the product and the method of measurement of: timber quality, properties and moisture content. They define the level of the equilibrium moisture content that depends on the wood species and the type of the parquet element. The elements of the timber structure – floor joists, binding joists, etc. must meet the requirements for the structural timber with a defined strength class C (softwood) or possibly D (hardwood) according to EN 338 in conjunction with the group of harmonized standards EN 14081-1, -2, -3 and -4. The dimensions of the cross-section of the members transferring load from the floor – such as floor joists, binding joists and posts should be designed according to the requirements of the design standard of EN 1995-1-1 (EC5). Wooden floor joists and binding joists and other structure members placed under the parquet (flooring) should be preserved with bio-protective agents, and under the surface of the floor there should be air circulation. In the book from the 1930s it is suggested to install floor joists every 450 mm – together with the 25 mm thick “blind” floor, every 650 mm – with 33 mm thick floorboards and every 800 mm – with 38 mm floorboards [Mielnicki 1938]. At present, technical felt or edge tape – expansion filler tape made of polyethene foam, is installed between floor joists and parquet to limit floor squeaking sounds. The dimensions of the cross-section of the beams depend on the method of their support. The beams should be 10–20 mm higher than the expected thermal and sound insulation, to preserve the ventilation gap. If the floor needs to be supported at the sheathing, its underlayment may be made of boards (requirements as above) or wood-based slabs meeting the requirements of standard PN-EN 13896 in the area provided for slabs used indoors as floor sheathing. Materials for water and thermal insulation, mixtures for cement mortar or screeds, mechanical joints, such as nails, binders, screws – must also meet the requirements of the harmonized standards. When performing the repair, special attention should be paid to the necessity of construction of the effective layer of water insulation always between masonry or brick background and a wooden member. The layers of the insulations usually made of felt paper may be glued only onto the primed underlayment. At this point it should be stressed that the base of the insulation layer as well as the wall in the building should not have the moisture content greater than 2%, while between the floor joists and the wall there should be at least 2 cm wide air gap. Structural members transferring loads may also include a solid base – compound – in contemporary floors usually made of concrete or screed. The floor screeds made of mineral materials are made of aggregate and binders (cement/anhydrite) in the amount that complies with the recipe for the required compressive strength or the ready mixture with the properties declared by the manufacturer, according to PN-EN 13813 and PN-EN 13318. Hardened screed made according to the recipe and the requirements of the technology should have – declared and estimated by the designer – compressive and bending strength. The value of the hardened screed strength may be verified, for example, with the test method as per PN-EN 13892-2 [31] and PN-EN 13892-1. Under timber floors or other wood-based materials not glued to the underlayment (floating flooring) the screed with the strength of at least C12 are used. The floor screeds with the strength of C20, C25, C30 or higher requirements, customized, e.g. reinforced, are used under wood flooring glued to the screed. Spacing and type of reinforcement should be defined in the building design. Steel members coming into contact with the anhydrite mortar should

109 be protected against corrosion. The requirements related to the thickness of the mineral screed layer are presented in table No. 1.

Table No. 1.The requirements related to the thickness of the layer of mineral screed cast on the construction site Minimum thickness of the cast screed, mm No. Flooring types. Cement Anhydrite screed screed 1 2 3 4 – of solid wood with dimensions: l < 500mm i b < 70mm - glued to the screeds, or – flooring made of sandwich panels, laminated panels or veneered panels, 1 40 40 that can transfer the point load up to 1.5 kN/m2 constructed on screeds cast on the thermal and sound insulation with compressibility of at least 70 kPa (installed on the waterproof or dampproof insulation) – of solid wood with dimensions: l < 1500mm i b < 120mm and minimum thickness t, of at least 1/7 of the width of the member and not less than 16 2 mm – that can transfer the point load up to 2.0 kN/m2 glued to screeds cast on 45 50 the thermal and sound insulation with compressibility of at least 100 kPa (installed on the waterproof or dampproof insulation) The parquet glued to the screeds or “floating” parquet that can transfer the 3 point load of up to 2.0 kN/m2, constructed on screeds with hydronic 60 60 underfloor heating or cooling Parquet with members larger than those mentioned above with or without Customized thickness of the 4 the underfloor heating screed l - length, b - width, t - member thickness

Table No. 2. Minimum durability of screeds under the flooring glued to the underlayment or floating Minimum screed durability N/mm2 Measurement*) with a tensile tester No. Flooring types. Compression Bending C F Vertically Horizontally (stretching) (shearing) 1 2 3 4 5 6 cast screed Under floating floorings made of laminated 1 12 4 - - panels or sandwich boards Under glued floorings made of mosaic tiles, 2 members of solid wood of national species with 20 5 1.0 1.5 small dimensions Under glued floorings made of solid wood of 3 European species, except for beech, with the 25 6 1.2 2.0 length of over 500 mm Under glued floorings made of solid wood, in 4 particular exotic wood, beech, hornbeam, with 30 6 1.5 2.5 significant plan dimensions Under glued floorings made of non-typical wood 5 species with significant plan dimensions or with Screeds with strength parameters, customized special requirements prefabricated screed Under floorings glued to the screed, mosaic, members of solid wood of national species, 6 > 25 > 5 > 1.5 > 2.5 except for beech, with the length of up to and over 500 mm Note: *) It is recommended to check the cohesion of screed layers and the adhesion of the adhesive to the screed, and in particular after reinforcing and leveling the screed.

110 Durability class of the floor mineral screed, cast or prefabricated, should be appropriate for the parquet installed on it and the expected operational load. The parameters of mineral screeds depending on the type of the parquet are provided in table No. 2, while table No. 3 includes the requirements for the maximum moisture content acceptable for the screed before the parquet is glued to it.

Table No. 3. Maximum moisture content in cement screeds, % Measurement method*) No. Screed type Meter Electric meter Weight and dryer CM*) 1 2 3 4 5 Screeds without underfloor heating – 1 ≤ 1.5 ≤ 3.0 ≤ 1.8 cement/concrete 2 Cement/concrete screeds with underfloor heating **) ≤ 1.5 ≤ 0.8 NOTE: *) Additives to the mortar or the metal member (reinforcement) may cause difficulties to assess errors in readings made with the use of resistance moisture meter, while the additives and admixtures to the mortar may cause difficulties to assess errors in measurements with the CM method. **) according to the declaration of the manufacturers of: screed and the heating system Fast drying screeds cannot be measured with the use of the CM method unless the manufacturer recommends this method and provides values at which the parquet can be installed. The manufacturer of the fast drying screed should provide the moisture content level appropriate for flooring installation as well as should specify how to check/measure it.

In the case of concrete underlayment and screeds it is necessary to isolate the source of moisture (e.g. if the flooring is installed on the soil). Then it is necessary to apply the insulation procedures and materials approved for use in construction, marked with CE mark, dedicated for specific applications (e.g. felt paper, rolled waterproofing membranes, liquid waterproofing membranes, etc.). According to the present standards, the point operation loads for house building industry are at least Qk=2 kN (for example for the furniture leg) or even 3 kN for the piano leg [PN-EN 1991-1-1]. In the event of antique floor renovation we cannot obtain a “perfectly flat” surface preferred in the contemporary flooring, while the flooring based on conservation patterns, installed with traditional methods should meet both the aesthetic requirements (appearance of the floor finishing, general impression) as well as contemporary technical requirements related, for example, to flatness, inclination (if required), resistance to dimension changes, resistance to abrasion of the coat, hardness, tight cracks, gloss, and in ballrooms also the energy absorption capacity within the required range of shock absorption.

Requirements for tiled parquet flooring Panels may be constructed with the use of traditional craft methods or contemporary industrial methods by adjusting the structure of the tile and flooring to the selected scope of reconstruction. For designed, stylized flooring it is recommended to use simple and clear geometric patterns based on maximum two wood species. These are exotic wood types often unprecedented in historic flooring, such as iroko mixed with oak [Kuczyńska-Cichocka 1999b]. Preserved historic panel parquets demonstrate the skills and ingenuity of parquet craftsmen and the contemporary attempts to reconstruct them teach respect for the skill in leveling and adjustment of members. Floor reconstruction, which takes into consideration floor structure, patterns and the used wood species, may be based on residually preserved original tiles or on the illustrations and more frequently photographs. It is one of the most difficult conservation methods since, usually with lean documentation, it not only requires an in-depth analysis of possible solutions for patterns or the applied wood species but also the

111 structure of the panel combined with the structure of the entire floor. The most popular reconstruction of this type in Poland was the reconstruction of the flooring in the Royal Castle in Warsaw performed in the years 1972–1983. It referred to the set of antique timber flooring dating back to the period of reconstruction of the Royal Castle in Warsaw by Stanisław August Poniatowski, which decorated almost all the interiors of the Castle until 1944. The reconstruction was performed by Zakłady Wytwórcze Mebli Artystycznych in Henryków. Few pre-war illustrations of flooring were used that were preserved in the collections of the National Museum and unfinished catalogue of the Rudolf Brothers (the known Warsaw manufacturing plant of parquets from the interwar period); archival photos were also analysed. These actions were reflected in the accuracy of the reconstruction both in terms of pattern and used wood species [Lewandowski 2001]. The photos show that tiles were laid on screeds and slabs [Zamkowe podłogi 1989]. Design and construction of the new parquet corresponding to the style and nature of the historic interior refer to the monuments where the decorative flooring was not preserved or had never existed but it is justified after its adaptive reuse. Designed flooring should take into consideration the degree of representativeness of the building, intended use of rooms and its infrastructure. It is also important to adjust the style of the flooring to the interior decor, the date of construction or conversion of the building. The scope of reconstruction is important. It covers only the pattern or also the floor structural solutions popular in the area. The tiles may be constructed with the use of traditional craft methods or contemporary industrial methods, by adjusting the structure of the tile and the floor to the selected scope of reconstruction which confirms the necessity of earlier works related to the historic analysis of the building and the patterns of parquet in a given region.

RESULTS AND CONCLUSIONS FROM PERFORMANCE TESTS The preservation condition of antique floors is affected by the material they were made of (wood species and its cross-section), the floor structure, the structure of the parquet, as well as the conditions of use of times related to microclimate in the room and the method of timber surface treatment (protection against moisture). The tests of fungus attack impact on the timber of the historic floors on the prospects for use showed that the fungus attacks do not force their necessary replacement (sometimes it is enough to use a fungicide and ensure proper moisture conditions by proper floor structure with ventilation). The results of detailed tests indicate that the basic criterion for further use of the historic floor involve the following properties of timber: density (ISO 3131), bending strength (PN- EN 408), hardness (PN-EN 1534), abrasion resistance (PN-ENISO 5470-1), scratch resistance (PN-EN 483-2), transfer of dynamic loads by shock absorption-force reduction (PN-EN 14808 and 14809) and the degree of fungus attacks assessed visually and by ergosterol determination with the use of the Seitz method [1979], moisture content change curve, equilibrium moisture content as well as quantitative and qualitative chemical composition. There is no doubt that it is possible to reuse antique timber floors, but the material properties of timber of some tested historic decorative floor indicate high quality of the used raw material. Therefore, despite timber deterioration caused by time and the conditions of use, they still meet the contemporary performance requirements, i.e. they allow to transfer static dead loads (floor layers) and dynamic loads generated as a result of the movement on the them, e.g. contemporary standards for operational point loads for house building industry, at the level of at least Qk=2 kN (for example the furniture leg) or even 3 kN for the piano leg (PN-EN 1991-1-1).

112 However, in the event of historic flooring renovation, we cannot obtain a “perfectly flat” surface preferred in contemporary flooring and we must be aware of serious deformations of tiles from the flatness and deformations of the shape of individual tile members (EN 13647). The reconstructed flooring based on conservation patterns, installed with traditional methods should meet both the aesthetic requirements (appearance of the parquet, general impression) as well as contemporary technical requirements related for example to the flatness, inclination (if required), resistance to dimension changes, resistance to abrasion of the coat, hardness, tight cracks, gloss, and in ball rooms also the energy absorption capacity within the required range of shock absorption.

SUMMARY Method selection of antique floor working out depends on its current technical condition and the predicted intended use and, if reasonable, the possibility to incorporate in the new floor as many preserved members as possible. A decision on the scope of the works may be difficult to made since the floor must meet the technical requirements and it should satisfy formal requirements. The results of tests and analyses of the historic floor form the introduction to the proper assessment of the suitability of the old floors for further use and the basis for development of the criterion determining whether the antique floor should be renovated or replaced. In the conservation works, the decisions on the applied materials and technologies should be made on the basis of valid construction standards while respecting the historic values of monuments and the historic substance.

REFERENCES 1. FRODL W., 1966: Pojęcia i kryteria wartościowania zabytków i ich oddziaływanie na praktykę konserwatorską. Ministerstwo Kultury i Sztuki, Zarząd Muzeów i Ochrony Zabytków, Warszawa. 2. KRAWCZYK J., 2004: Wartości historyczne mebli zabytkowych, Rocznik Akademii Rolniczej w Poznaniu, 71-82. 3. KRAWCZYK J., 2006: Meble jako przedmioty użytkowe i zabytki. U podstaw problematyki konserwatorskiej mebli zabytkowych, Wydawnictwo Uniwersytetu Mikołaja Kopernika, Toruń. 4. KURZĄTKOWSKI M., 1998: Mały słownik ochrony zabytków, Ministerstwo Kultury i Sztuki, Warszawa. 5. KUCZYNSKA-CICHOCKA B., 1999a: Parkiety zabytkowe - rozważania konserwatorskie, Podłoga 8: 23-25. 6. KUCZYNSKA-CICHOCKA B., 1999b: Rekonstrukcja parkietów taflowych, Podłoga 10: 17-21. 7. LEWANDOWSKI H., 2001: Henrykowskie posadzki w Warszawskim Zamku Królewskim 1972-1983, w: Restytucja Zamku Królewskiego w Warszawie, praca zbiorowa, Wydawnictwo Projekt, Warszawa, 170-185. 8. MIELNICKI St., 1938: Ustroje budowlane- Podręcznik z przykładami konstrukcyj budowlanych w 190 tablicach rysunkowych z opisem, w: Podłogi klepkowe i parkietowe, 2002: Podłoga 9. 9. POMIAN K., 1996: Zbieracze i osobliwości. Paryż-Wenecja XVI-XVIII wiek, tłum. A.Pieńkos, Warszawa. 10. SEITZ L.M., SAUER D.B., BURROUGHS R., MOHR H.E., HUBBARD J.D., 1979: Ergosterol as a measure of fungal growth, Phytopatology 69: 1202-1203. 11. Ustawa o Ochronie Zabytków i Opiece nad Zabytkami z 23 lipca 2003 r. - Dz. U. z dnia 17 września 2003 r.

113 12. Ustawa o Wyrobach Budowlanych z maja 2004 Dz. U. nr 92 poz. 881, z późniejszymi zmianami. 13. VONDUNG M., 2001a: Drewniane konstrukcje podłogowe, Podłoga 6: 30-33. 14. WOŹNIAK T., 2011: Osuszanie podkładów pod podłogi drewniane, Podłoga 1: 17-21. 15. Zamkowe podłogi, 1989: Spotkania z Zabytkami: 34-36.

Streszczenie: Metody i możliwości konserwacji historycznych podłóg drewnianych w świetle obowiązujących norm budowlanych. W niniejszej pracy przedstawiono pogląd na uwarunkowania prawne rekonstrukcji i renowacji podłóg drewnianych - czyli zadań polegających na odtworzeniu zniszczonego obiektu w celu zabezpieczenia go przed całkowitym unicestwieniem, przy zastosowaniu wszelkich środków dla zachowania wartości historycznych obiektu, zabezpieczeniem stanu oryginalnego łącznie z możliwością uzupełnienia elementów zabytkowych, oraz renowacji - której zadaniem jest odnowienie zniszczonego zabytku, poprzez odtworzenie elementów zabytkowych.

Słowa kluczowe: zabytkowe podłogi ozdobne, konserwacja podłóg, renowacja i rekonstrukcja podłóg

Corresponding author:

Anna Policińska-Serwa Instytut Techniki Budowlanej 00-611 Warszawa, ul Filtrowa 1 Tel:+48 22 5664 409 e-mail: [email protected]

114 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 115-119 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Adhesion of foils to MDF board

GABRIELA SLABEJOVÁ, MÁRIA ŠMIDRIAKOVÁ, JÁN PETRIĽÁK Department of Furniture and Wood Products, Faculty of Wood Sciences and Technology, Technical University in Zvolen

Abstract: Adhesion of foils to MDF board. The article deals with adhesion of foils to MDF board. Foiled furniture parts made from MDF board are one of the alternatives of coating. The aim of our work was to study the effect of adhesive spread on adhesion of two types of foils (PVC and PET). Two-component polyurethane adhesive was used. The adhesive spread was of the recommended amount, or the amount reduced by 50 %, or increased by 50 %. Boards with both types of foils were pressed at the same pressing mode. Adhesion was determined by the Pull- off test for adhesion. After pull of strength measurement, the metal discs were analysed and the place of failure was determined. For both types of foils, the failure was in the adhesive layer. The surfaces with PET foil showed higher adhesion. The highest adhesion was measured on the specimens with the recommended adhesive spread for both PET and PVC foils. Both reduction and increase in the adhesive spread resulted in reduced adhesion of foils to MDF board.

Keywords: MDF board, PVC film, PET film, adhesion, Pull-off test

INTRODUCTION The finish is an important technology that ensures high aesthetic function of a product and also its protection. To finish a product, different coating materials, foils, or laminates are applied. At present, flat furniture parts are most often made from chipboard, MDF, or HDF boards. These materials are mainly finished with laminates, foils, or coating powders. The coating powders and using of them were evaluated by Wuzella et al. (2014). The quality of surface finish is affected by quality of the base material, but especially by quality of coatings and foils. The surface roughness of MDF was researched by Hiziroglu (1996) and Kilic et al. (2009). Kilic et al. (2009) investigated the effect of roughness on adhesion using the Pull-off test for adhesion. The quality of the base material and quality of foils were evaluated also by measuring of the wettability of the surface and the surface energy, as reported by Sinn et al. (2005) and Novák et al. (2016). The base material and especially the technology of the surface treatment affect significantly the adhesion of a paint coating or a foil. Determination of adhesion was reported by Kúdela, Liptáková (2006), Slabejová (2012), and Štrbová et al. (2015). Currently, there is a trend to improve the properties of already known types of coating materials and foils. Modification of PTFE foil was researched by Wang et al. (2000). The adhesion of PES foil after plasma treatment was reported by Novák et al. (2016). The aim of the present work was to study the effect of the adhesive spread on adhesion between MDF and a foil. Two types of foils (PVC, PET) were examined. The adhesion was assessed using the Pull-off test for adhesion.

MATERIALS AND METHODS In the experiment, the test specimens of medium-density fibreboard (MDF) (manufacturer Bučina DDD Zvolen) with dimensions of 18 mm × 700 mm × 300 mm were used. Two types of foils were used to finish the MDF: PVC foil (white, high gloss) and PET foil (black – mirage, high gloss) (manufacturer Domator), both with a thickness of 0.5 mm.

115 To glue the foils to MDF, the PUR adhesive Dorus Fd 150 Ls Plus and the hardener Dorus R 397 (3 – 10 %) (manufacturer Henkel) were used. Dorus Fd 150 Ls Plus is a two- component dispersion adhesive for 3D lamination of foiled parts. The main surfaces and the edges of the MDF test specimens were sanded with sandpaper with grit number P180. After sanding, the adhesive was applied with a spray gun in one coat, but in three different spreads: • recommended (100 – 120 g/m2), • reduced by 50 % (50 – 60 g/m2), • increased by 50 % (150 – 180 g/m2). Open time of the adhesive was 1 hour, and then the set with a foil was vacuum pressed, without membranes, using the vacuum press Bürkle Multiformpresse ODWMP. Pressing mode was the same for both types of foils. The pressing cycle parameters were: time of 80 seconds, temperature of the top plate 130 °C, and pressure of 0.38 MPa. After cooling the test specimens, the overhanging foil was trimmed. The test pieces were conditioned in a room at temperature of 20 ± 2 °C and humidity of 60 ± 5 % for 30 days. The adhesion of the foil to MDF board was determined using the Pull- off test according to the standard EN ISO 4624: 2002. Surface of the coating was lightly sanded (sandpaper with grit number of P280) and then cleaned. Two-component epoxy adhesive (Pattex REPAIR epoxy) was applied onto the touch pad of metal disc (d = 20 mm); and then the disc was glued to the test specimen. The disc was burdened to cure the adhesive for 24 hours. After towing, an annular ring was milled around glued disc, thus removing the foil throughout its thickness up to the base board. The disc was clamped to the equipment PosiTest AT – Pull-Off Adhesion Testers and detached from the surface of the test specimen. The tensile stress σA [Pa] at which the system of MDF – adhesive – foil failed was recorded. Also the place in the system where the failure occurred was monitored.

RESULTS AND DISCUSSION The measured values of pull of strength σA were evaluated by two-factor analysis of variance using the STATISTICA. The influence of the type of foil and the adhesive spread on adhesion (stability of the system MDF – adhesive – foil) was monitored. Both factors affect the stability at tension statistically high significantly. The graph in Fig. 1 shows that higher pull of strength was achieved by the specimens with PET foil, if compared with the specimens with PVC foil. Fig. 2 shows that the highest value of pull of strength was achieved by the specimens glued by recommended adhesive spread. At the specimens with PVC foil, the adhesive spread reduced by 50 % resulted in reduced pull of strength (from 0.77 MPa to 0.55 MPa); and increased adhesive spread also resulted in decreased pull of strength (to 0.6 MPa). At the PET foil, the recommended adhesive spread reached the pull of strength of 0.95 MPa, the reduced spread 0.67 MPa, and increased adhesive spread reached the pull of strength of 0.85 MPa. Fig. 1 and Fig. 2 show that higher pull of strength was achieved by the system with PET foil. After analysing the metal disc, we can conclude that the failure occurred on the whole area of the disc, in the surface layer of MDF board impregnated by the adhesive. Also wood fibers from the surface of MDF board, which were reinforced by the adhesive, remained on the disc. Such breach occurred on specimens both with PET (Fig. 3) and PVC foils at all three adhesive spreads. The analysis of metal discs shows that the measured values of pull of strength of the system (MDF – adhesive – foil) correspond to cohesion of impregnated fibers on the surface. We can assume that the actual adhesion is equal to, or a slightly higher than, the measured values of the pull of strength. Kilic et al. (2009) reported that the adhesion is increasing when the surface roughness of the MDF board is reducing, but the increase is not statistically

116 significant. From that it follows that the important factors that significantly affect the adhesion are the type and quality of the foil and adhesive spread. The foil quality can be modified by various technological operations, for example by plasma, as reported by Novák et al. (2016).

Fig. 1 Pull of strength of system (MDF – adhesive – foil) for both types of foil.

Fig. 2 Dependence of pull of strength of system (MDF – adhesive – foil) on adhesive spread for both tested foils.

117

Fig. 3 Metal discs after Pull-off test for adhesion. From left: recommended, reduced, and increased adhesive spread.

CONCLUSIONS Based on the measured results using the Pull-off test for adhesion and the analysis of metal discs, we can conclude: • The type of the foil affected the size of adhesion to the surface of MDF boards significantly. PET foil showed higher adhesion when compared with PVC foil. • If reducing the adhesive spread or increasing it, the adhesion of PVC foil decreased significantly. • For the PET foil, the adhesion decreased significantly if the adhesive spread was decreased. If the adhesive spread was increased, the difference in adhesion was not statistically significant, when compared with recommended adhesive spread. • The weakest spot of the system MDF – adhesive – foil in the Pull-off test for adhesion was the surface layer of MDF board with the fibers impregnated by the adhesive.

REFERENCES 1. HIZIROGLU, S. 1996. Surface roughness analysis of wood composites: A stylus method. In Forest Products Journal [online]. 1996, 46(7–8): 67–72. [Online]: https://www.scopus.com/record/display.uri?eid=2-s2.0- 0002880654&origin=reflist&recordRank 2. KILIÇ, M., BURDURLU, E., ASLAN, S., ALTUN, S., TÜMERDEM, Ö. 2009. The effect of surface roughness on tensile strength of the medium density fiberboard (MDF) overlaid with polyvinyl chloride (PVC). In Materials & Design [online]. 2009, 30(10): 4580–4583. [Online]: http://www.sciencedirect.com/science/article/pii/S0261306909001332 3. KÚDELA, J., LIPTÁKOVÁ, E. 2006. Adhesion of coating materials to wood. In Journal of Adhesion Science and Technology [online]. 2006, 20(8): 875–895. [Online]: http://www.tandfonline.com/doi/abs/10.1163/156856106777638725 4. SINN, G., MAYER, H., STANZL-TSCHEGG, S. 2005. Surface properties of wood and MDF after ultrasonic-assisted cutting. In Journal of Materials Science [online]. 2005, 40(16): 4325–4332. [Online]: http://link.springer.com/article/10.1007%2Fs10853-005- 1995-7 5. NOVÁK, I., SEDLIAČIK, J., GAJTANSKÁ, M., SCHMIDTOVÁ, J., POPELKA, A., BEKHTA, P., KRYSTOFIAK, T., PROSZYK, S., ŽIGO, O. 2016. Effect of barrier plasma pre-treatment on polyester films and their adhesive properties on oak wood. In BioResources [online]. 11(3), 6335-6345. [Online]: https://www.ncsu.edu/bioresources/

118 6. SLABEJOVÁ, G. 2012. Influence of selected factors on the stability of wood - solid coating film. In Acta Facultatis Xylologiae. 2012, 54(2): 57–65. 7. ŠTRBOVÁ, M., TESAŘOVÁ, D., KÚDELA, J. 2015. Adhesion of UV-curable coatings to beech wood. In Materials Science Forum [online]. 2015, 818: 202–205. [Online]: https://www.scopus.com/record/display.uri 8. WANG, P., TAN, K. L., KANG, E. T. 2000. Surface modification of poly(tetrafluoroethylene) films via grafting of poly(ethylene glycol) for reduction in protein adsorption. In J Biomater Sci Polym Ed [online]. 2000, 11(2): 169–186. [Online]: http://www.ncbi.nlm.nih.gov/pubmed/10718477 9. WUZELLA, G., KANDELBAUER, A., MAHENDRAN, A. R., MÜLLER, U., TEISCHINGER, A. 2014. Influence of thermo-analytical and rheological properties of an epoxy powder coating resin on the quality of coatings on medium density fibreboards (MDF) using in-mould technology. In Progress in Organic Coatings [online]. 2014, 77(10): 1539–1546. [Online]: http://www.sciencedirect.com/science/article/pii/S0300944014000423

Acknowledgements: This work was supported by the Slovak Research and Development Agency under the contract No. APVV-15-0235. The authors are grateful for the support of VEGA agency, grant No. 1/0626/16.

Streszczenie: Adhezja folii do MDF. Praca dotyczy adhezji folii używanych w meblarstwie do płyt MDF. Testowano 2 typy folii (PVC i PET) oklejanych przy pomocy dwuskładnikowego kleju poliuretanowego. Badania na odrywanie wykazały że oderwanie następuje w spoinie przy obu typach folii, zarówno zmniejszenie jak i zwiększenie naniesienia powodowało obniżenie wytrzymałości..

Corresponding authors:

Ing. Gabriela Slabejová, PhD. Ing. Mária Šmidriaková, PhD. Ing. Ján Petriľák Department of Furniture and Wood Products, Faculty of Wood Sciences and Technology Technical University in Zvolen, T.G. Masaryka 24 960 53 Zvolen, Slovakia [email protected] [email protected]

119 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 120-124 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Quality of finish on bonded layered material made from beech veneer and foamed PVC

GABRIELA SLABEJOVÁ, MÁRIA ŠMIDRIAKOVÁ, ZUZANA GAJDOŠÍKOVÁ Department of Furniture and Wood Products, Faculty of Wood Sciences and Technology, Technical University in Zvolen

Abstract: Quality of finish on bonded layered material made from beech veneer and foamed PVC. The article deals with quality of finish on bonded layered material made from beech veneer and foamed PVC. The finish was formed of water-based coating materials. Physical and mechanical properties were evaluated according to the standards STN 67 3082/a Testing of impact resistance of paint coatings and STN EN ISO 15184:2012 Determination of film hardness by pencil test. Water-based coating material PAMLAK with density of 1050 kg/m3 formed coatings of almost the same quality, in terms of surface hardness and impact resistance, on both substrates (beech veneer and foamed PVC). The coating materials HOBBYLAK and KIVA with density of 1000 kg/m3 formed coatings, which quality at mechanical stress was strongly influenced by the substrate.

Keywords: beech veneer, water-based coating material, glued layered material, foamed PVC, mechanical resistance

INTRODUCTION Wood is an anisotropic material of relatively inhomogeneous structure, formed by macromolecular substances (cellulose, hemicelluloses, lignin and extractives). Wood is characterized by sufficient strength, flexibility, good heat insulating, and specific acoustic performance (Kačík et al. 2010). Wood has many positive characteristics, but also some deficiencies, e.g. insufficient dimensional stability. To achieve better dimensional stability and improve mechanical properties of wood, wood layered materials are produced. The composite materials are materials of large-scale dimensions, characterized by steadiness of mechanical properties, and greater resistance to the environment (King, Hrázský, 2005). The traditional composite layered materials are plywood and laminated timber. Currently, in practice, the composite materials having a layer of modified wood or a layer of other material (e.g. synthetic polymer) are used. Veneers modified by pressing were researched by Bekhta et al. (2016). Various modifications of wood were dealt by Shulga (2015), Zemiar et al. (2014), Langová, Joščák (2014), and Slabejová, Šmidriaková (2014). Slabejová and Šmidriaková (2013) researched the bonding strength of composite material made from beech veneer and foamed PVC. Just like the surface of solid wood, the surface of bonded layered material must be finished. The aim of this study was to determine the resistance of coatings on the surface of bonded layered material (beech veneer and foamed PVC) against selected mechanical load. The film hardness of coatings and the impact resistance of coatings were assessed.

MATERIALS AND METHODS In experiments, beech wood (Fagus sylvatica L.) and foamed PVC were used. These two materials may be used for production of a layered material, the surface of which will subsequently be finished by coating materials. The specimens’ dimensions were: • Beech veneer: 300 mm × 300 mm × 2.6 mm, wood moisture content of 8 ± 2 %, the 3 average density at zero moisture content ρ0 = 676 kg/m . • Foamed PVC sheet: 300 mm × 300 mm × 3 mm.

120 Before testing, the specimens were conditioned at room temperature 23 ± 2 °C and relative humidity 60 ± 5 % for 28 days. Then the surface of the test pieces was finished by water-based coating materials applied by brush. Selected coating materials were: • HOBBYLAK (density cca 1000 kg/cm3, non-volatile components min. 37 % mass, consistency F4 / 23 ºC min. 45 s, pH: 7-8). • PAMLAK (density cca 1050 kg/m3, non-volatile components min. 30 % mass, consistency F4 / 23 °C min. 25 s). • KIVA (density cca 1000 kg/cm3, non-volatile components min. 32 % mass). All the chosen coating materials had to meet the following: • water-based acrylic paint for wood, • suitable for children's furniture and toys, • aplied by brush, roller or spray. After curing, the paint coatings had the thickness summarised in Table. 1. Paint coatings' thickness was measured using non-destructive method with the PosiTector 200.

Tab. 1 Thickness of cured paint coatings Coating thickness on substrate [μm] HOBBYLAK KIVA PAMLAK Beech veneer 34.8 42.8 40.6 Foamed PVC 43.33 45.33 41.33

Impact resistance of paint coatings was tested according to STN 67 3082/a Testing of impact resistance of paint coatings. The weight (mass of 500 g) was launched on the metal ball (d = 14 mm) from six drop heights (10, 25, 50, 100, 200, or 400 mm) in free fall. The diameter of the ball imprint on the surface and degree of damage were measured. The degree of damage after testing of impact resistance of paint coatings was evaluated visually according to the following scale: 1. No visible changes. 2. No cracking on the surface; the imprint after hit is almost invisible under ideal conditions. 3. Small cracks on the surface, usually 1 or 2 ring cracks; the cracks may form only the peripheral zone, not a complete circle. 4. Moderate to large cracks, confined to the imprint after hit. 5. Cracks extend beyond the imprint after hit; the paint is peeled. The surface hardness was determined using pencils according to EN ISO 15184: 2012 Determination of film hardness by pencil test. Each testing pencil was clamped in the preparation and loaded with the weight of 300 ± 15 g. Pencil drew the wavy line on the surface. We rated visually, which of the pencils damaged the surface (scratched the paint coating).

RESULTS AND DISCUSSION The results of determination of surface hardness are summarized in Table. 2. The underlying material (substrate) affected significantly the film hardness for coatings of HOBBYLAK and KIVA. KIVA coating on the foamed PVC substrate reached the film hardness of grade 2 only, but on beech veneer substrate the hardness of grade 8. HOBBYLAK coating on the foamed PVC reached the film hardness of grade 3 and on beech veneer grade 9. Interestingly, the coating PAMLAK reached greater film hardness on the foamed PVC substrate (grade 8) than on beech veneer (grade 7). If comparing the individual paint coatings, we can see that PAMLAK creates a coating with film hardness of similar values on beech veneer substrate as well as on the foamed PVC substrate. This feature is desirable for the surface finish on layered products, if the layered product is made from two different materials. The layers are

121 visible and stressed both on the side and on the main surface. Aesthetically, the main surface made of veneer may be perforated, and so the layer of foamed PVC is also visible.

Tab. 2 Results for film hardness by pencil test Film Pencil Beech veneer Foamed PVC Hardness hardness Pamlak Hobbylak Kiva Pamlak Hobbylak Kiva 1 3B 2 2B x 3 B x 4 HB 5 F 6 H 7 3H x 8 4H x x 9 5H x 10 6H 11 7H 12 8H 13 9H

Results of testing of impact resistance of paint coatings are summarised in Table 3 and 4.

Tab. 3 Ball imprint diameter and Impact resistance on beech veneer Ball imprint diameter [mm] Drop Impact height HOBBYLAK PAMLAK KIVA resistance [mm] 10 1 25 2 3 2 50 2 3 4 2 100 3 4 5 3 200 5 5 6 3 400 6 7 8 3

Tab. 4 Ball imprint diameter and Impact resistance on foamed PVC Ball imprint diameter [mm]

Drop height Impact HOBBYLAK PAMLAK KIVA [mm] resistance

10 4 3 4 2 25 5 4 6 2 50 7 6 7 3 100 8 7 8 3 200 9 8 10 4 400 10 9 15 4

122 As shown in Table 3 and Table 4, impact resistance (degree of surface damage) of all three tested coating materials are the same. Differences are in the size of the ball imprint. On the beech veneer, the smallest imprint was measured for HOBBYLAK paint coating. On the foamed PVC substrate, the smallest imprint, for each drop height, was measured for PAMLAK paint coating. The smallest differences in size of the imprint on the beech veneer substrate and imprint on the foamed PVC substrate were reached by PAMLAK paint coating (Tab. 3 and 4). Water-based coating material PAMLAK provides the surface with resistance to scratching and impact resistance of almost the same quality on both substrates (beech veneer and foamed PVC).

CONCLUSIONS Based on the observed results, we can make the following conclusions: • Coating material PAMLAK (density of 1050 kg/m3) formed a coating of almost the same quality, in terms of surface hardness and surface resistance to impact, on both substrates – beech veneer and the foamed PVC. • Coating material PAMLAK is suitable for finishing of glued laminated material made from beech veneer and foamed PVC, in terms of impact resistance and surface hardness. • Coating materials HOBBYLAK and KIVA (density of 1000 kg/m3) formed a coating, the quality of which and the resistance to mechanical stress was strongly influenced by the substrate material.

REFERENCES 1. BEKHTA, P., MAMOŇOVÁ, M., SEDLIAČIK, J., NOVÁK, I. 2016. Anatomical study of short-term thermo-mechanically densified alder wood veneer with low moisture content. European Journal of Wood and Wood Products. 2016, 1–10. 2. KAČÍK, F., KUBOVSKÝ, I., JAMNICKÝ, I., SIVÁK, J. 2010. Zmeny sacharidov pri ožarovaní javorového dreva CO2 laserom. Acta Facultatis Xylologiae. 2010. 52(1): 33– 40. ISSN 1336-3824. 3. KRÁL, P., HRÁZKY, J. 2005. Kompozitní materiály na bázi dřeva.2. Část: Mendelova Zemědělská a Lesnická univerzita v Brně, 2005. 154 p. ISBN 80-7157-878-9. 4. LANGOVÁ, N., JOŠČÁK, P. 2014. Effect of mechanical modification of wood veneers on their planar formability. Annals of Warsaw University of Life Sciences. Forestry and Wood Technology. 2014, (87): 142–147. ISSN 1898-5912. 5. SHULGA, G., NEIBERTE, B., VEROVKINS, A., JAUNSLAVIETIS, J., SHAKELS, V., VITOLINA, S., SEDLIAČIK, J. 2015. Eco-friendly constituents for making wood- polymer composites. International Symposium on Selected Processes at the Wood Processing. 2015. ISSN: 1013-9826. 6. SLABEJOVÁ, G., ŠMIDRIAKOVÁ, M. 2014. Influence of modification of veneers on 3D - forming. Annals of Warsaw University of Life Sciences. Forestry and Wood Technology. 2014. (85): 226–229. ISSN 1898-5912. 7. SLABEJOVÁ, G., ŠMIDRIAKOVÁ, M. 2013. Bending strength of layered material based on wood and foamed PVC. Annals of Warsaw University of Life Sciences. Forestry and Wood Technology. 2013. (84): 180–185. ISSN 1898-5912. 8. ZEMIAR, J., FEKIAČ, J., GÁBORÍK, J. 2014. Strengthening of veneers for 3D- forming. Annals of Warsaw University of Life Sciences. Forestry and Wood Technology. 2014. (88): 297–303. ISSN 1898-5912.

123 Streszczenie: Jakość wykończenia powierachni materiału warstwowego z fornirów bukowych i spienionego PCW. Artykuł opisuje jakość wykończenia powierachni materiału warstwowego z fornirów bukowych i spienionego PCW, wykończonego lakierem wodorozcieńczalnym. Wykonano badania własności mechanicznych zgodnie z normą STN 67 3082/a oraz testy udarności powłok zgodnie z STN EN ISO 15184:2012 . Worodozcieńczalny lakier PAMLAK o gęstości 1050 kg/m3 stworzył powłoki o takiej samej jakości mierzonej udarnością I twardością na obu testowanych materiałach. Lakiery HOBBYLAK i KIVA o gęstości 1000 kg/m3 tworzyły powłoki o jakości zależnej od pokrywanego materiału.

Corresponding authors:

Ing. Gabriela Slabejová, PhD. Ing. Mária Šmidriaková, PhD. Ing. Zuzana Gajdošíková Department of Furniture and Wood Products, Faculty of Wood Sciences and Technology Technical University in Zvolen, T.G. Masaryka 24 960 53 Zvolen, Slovakia [email protected] [email protected]

124 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 125-129 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The colour changes of pinewood after weathering

GABRIELA SLABEJOVÁ, ZUZANA VIDHOLDOVÁ, JAKUB KALOČ Faculty of Wood Sciences and Technology, Technical University in Zvolen

Abstract: The paper evaluates the colour changes after weathering in the exterior of pinewood. It also monitors the influence of two examined factors on the colour change of surface; the two factors being: the length of exposure in the exterior and parts of wood – sapwood, heartwood. The submitted article deals with colour changes occurring on the sapwood and the heartwood. The changing colour of the surface was evaluated on samples exposed in the exterior for the period of 1 and 3 months. The colour was also evaluated on samples stored in dark places where there was no exposure to weathering. No significant colour changes were occurred on pine sapwood than heartwood. Significant colour changes were occurred on the exposure surface pine wood after weathering and cause different colour of surface. The higher colour change was found in pine wood (sapwood and heartwood) after first month weathering than between first and third month. The colour changes are easily seen with the naked eye.

Keywords: colour change, weathering, pine, heartwood, sapwood,

INTRODUCTION One of the aesthetics of the wood surface is its colour. Wood as a heterogeneous material depending on wood species has a different colour sapwood and heartwood, spring and summer wood, or the slight differences reflected on the various surfaces of wood. In some wood species, these differences are very significant, but others are almost negligible (Slabejová, 2013). Change of chemical composition of wood after weathering were increased due to solar radiation, change in temperature, water include changes in humidity, rainfall, icing and hail, wind include flow of liquid and gaseous media, air dust and pollutants - gaseous and biological and subsequently in wood increased colour change (Matsuo et al., 2011). Zahri et al. (2007) were study the photodegradation process by UV of two European oak species and their study were prove the photosensibility of oak wood extractives which, would strongly result in the discolouration of oak heartwood. The wood surface discolouration due to simulated sunlight of tropical woods was studied in Baar, Gryc (2010). The influence of accelerated ageing on surface-treated wood was investigated in Kúdela et al. (2016). The influence of natural weathering of surface-treated wood was investigated Pánek, Reinprecht (2016a) and Pánek, Reinprecht (2016b). The aim of this work was to assess the natural ageing influence on colour changes in surface wood in exterior in winter time. These changes were evaluated separately for sapwood and heartwood of pine.

MATERIALS AND METHODS For the experiment were prepared sapwood and heartwood samples of pine wood (Pinus sylvestris L.). Samples were the dimension of 150 ± 2 mm × 74 ± 1 mm × 16 ± 1 mm. Moisture of samples was 14 ± 2%. Samples have been before explosion grinded along wood gains with 60, 80 and 120-grit sandpaper by using a belt grinder. Subsequently, they were exposed to the natural weathering. Natural weathering of sapwood and heartwood samples was carried out on the metal stands at 45° slope oriented to the South outside the Technical University in Zvolen, Slovakia, at ca. 300 m above sea level. Weathering took place from December 18, 2015 to March 18, 2016 for period of one and three months. Reference samples were packed in aluminium foil and were deposit in dark room.

125 Colour changes of samples were recorded before initial exposure and after one and three months with a spectral photometer Colour Reader CR-10. Colour changes were evaluated using CIE L*a*b* colour system and ΔE* was calculated and used for comparison of colour changes among different specimens (CIE 1986). Average values of sapwood and heartwood samples are calculated from at least 48 measurements (four measurements per sample).

∆E* = ∆L *2 ∆+ a *2 ∆+ b*2 (1)

Where: L* – the lightness or brightness of the colour, a* – is the coordinate with colour between green and red, b* – is the coordinate with colour between blue and yellow.

Table 1 Colorimetric evaluation (Allegretto et al. 2009) Colour change - ΔE* Colour change 0.2>ΔE* Invisible difference 0.2<ΔE*<2 Little difference 2<ΔE*<3 Colour difference visible with high quality screen 3<ΔE*<6 Colour difference visible with medium quality screen 6<ΔE*<12 High colour difference ΔE*>12 Different colour

RESULTS AND DISCUSSION Colour changes of sapwood and heartwood samples were determined after first and third month exposure in winter and are shown in Figure 1 and 2. Differences in intensity of colour changes between sapwood and heartwood were found. Sapwood has colour change ΔE* from 10 to 24 after one month and from 17 to 25 after three months weathering. Heartwood has colour change ΔE* from 9 to 20 after one month and from 13 to 23 after three months weathering. In both cases, colour changes can classify as a different colour. Colour changes were occurred in weathered sapwood wood than in weathered heartwood of pine (Figure 1), but ones were no statistically significant (Table 1). Higher total colour change was found in pine wood (sapwood and heartwood) after first month weathering than between first and third month.

Figure 1 Colour changes of sapwood and heartwood – (a) unexposed and (b) after one and three months of weathering

126

a) Sapwood without weathering d) Heartwood without weathering

b) Sapwood after one month of weathering e) Heartwood after one month of weathering

c) Sapwood after three months of weathering f) Heartwood after three months of weathering

Figure 2 Colour of pine samples (Pinus sylvestris L.)

Table 1. Analysis of variance results of colour change after weathering

Factors Degrees of Sum of Mean F-values Probability freedom squares square α = 0.05 Sapwood/Heartwood (A) 1 23,552 23,552 3,1118 0,0947 Weathering time (B) 2 1714,542 857,271 113,2649 0,0000* Interaction (AB) 2 12,626 6,313 0,8341 0,4504 Error 18 136,237 7,56918 7,569

Total 1 3349,245

NOTE: * Significant difference

The results of our experiments confirm the conclusions of the work Baar, Gryc (2010) and Slabejová (2013). The most distinctive discolouration of wood was found in the initial brightest wood sapwood, the darkest heartwood was affected the least.

CONCLUSIONS Sapwood and heartwood samples of pine (Pinus sylvestris L.) were exposed to the natural weathering in winter time. Based on measured values of colour chance after weathering, we can conclude: − no significant colour changes were occurred on pine sapwood than heartwood, − significant colour changes were occurred on the exposure surface pine wood after weathering and cause different colour of the surface, − higher colour change was found in pine wood (sapwood and heartwood) after first month weathering than between first and third month.

127 REFERENCES

1. ALLEGRETTO, O., TRAVAN, L., CIVIDINI, R. 2009. Drying techniques to obtain white Blecha. Improvement of Wood Drying Quality by Conventional and Advanced Drying Techniques [online]. 2009, 19. Dostupné na internete: http://timberdry.net/downloads/EDG-SeminarBled/Presentation/EDG Seminar_Bled_2009_Travan.pdf 2. BAAR, J., GRYC, V. 2010. Analýza barvy dřeva a její změny vlivem simulovaného slunečního záření u tropických dřev. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis [online]. 2010, 58(5): 13–20. Dostupné na internete: http://www.mendelu.cz/dok_server/slozka.pl?id=45392;download=68244 3. CIE 1986. Colorimetry. 2nd Edition, CIE Pub. No. 15.2. Commission Internationale de l´Eclairage, Vienna, 74. 4. KÚDELA, J., ŠTRBOVÁ, M., JAŠ, F. 2016. Influence of accelerated ageing on colour and gloss changes in tree of heaven surface treated with an Iruxil coating system. Acta Facultatis Xylologiae Zvolen. 2016, 58(1): 25–34. 5. MATSUO, M., YOKOYAMA, M., UMEMURA, K., SUGIYAMA, J., KAWAI, S., GRIL, J., KUBODERA, S., MITSUTANI, T., OZAKI, H., SAKAMOTO, M., IMAMURA, M. 2011. Aging of wood – Analysis of color changes during natural aging and heat Treatment. Holzforschung, 2011, 65(3): 361–368. 6. PÁNEK, M., REINPRECHT, L. 2016a. Effect of the number of UV-protective coats on the color stability and surface defects of painted black locust and norway spruce woods subjected to natural weathering. BioResources. 2016, 11(2): 4663–4676. 7. PÁNEK, M., REINPRECHT, L. 2016b. Effect of vegetable oils on the colour stability of four tropical woods during natural and artificial weathering. Journal of Wood Science. 2016, 62(1): 74–84. 8. SLABEJOVÁ, G., 2013. Fotostabilita transparentných povrchových úprav bukového dreva. Acta Facultatis Xylologiae Zvolen. 2013, 55(2): 5–12. ISSN 1336-3824. 9. ZAHRI, S., BELLONCLE, C., CHARRIER, F., PARDON, P., QUIDEAU, S., CHARRIER, B. 2007. UV light impact on ellagitannins and wood surface colour of European oak (Quercus petraea and Quercus robur). Applied Surface Science [online]. 2007, 11(11): 4985–4989. Dostupné na internete: www.sciencedirect.com

Acknowledgements

The authors are grateful for the support of VEGA agency, grant No. 1/0626/16 and by the Slovak Research and Development Agency under the contract No. APVV-0200-12.

128

Streszczenie: Zmiana barwy drewna sosnowego pod wpływem warunków środowiskowych. Praca ocenia zmiany barwy drewna sosnowego pod wpływem warunków zewnętrznych. Brano pod uwagę długość ekspozycji oraz czy drewno jest bielaste czy twardzielowe. Próbki eksponowano na 1 do 3 miesięcy, próbkami kontrolnymi był materiał przetrzymywany w ciemności. Największą zmianę barwy, widoczną gołym okiem, zanotowano w pierwazym miesiącu ekspozycji.

Corresponding authors:

Gabriela Slabejová, Jakub Kaloč Department of Furniture and Wood Products, Faculty of Wood Sciences and Technology Technical University in Zvolen, T.G. Masaryka 24 960 53 Zvolen, Slovakia [email protected]

Zuzana Vidholdová Department of Mechanical Technology of wood, Faculty of Wood Sciences and Technology Technical University in Zvolen, T.G. Masaryka 24 960 53 Zvolen, Slovakia [email protected]

129 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 130-137 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Modeling of non-isothermal moisture transfer and visco-elastic deformation of wood as a fractal structure

YAROSLAW SOKOLOVSKYY Department of information technologies, National Forestry University of Ukraine VOLODYMYR SHYMANSKYI Department of information technologies, National Forestry University of Ukraine IGOR KROSHNYI Department of information technologies, National Forestry University of Ukraine OLGA MOKRYTSKA Department of information technologies, National Forestry University of Ukraine OLEKSANDR STOROZHUK Department of information technologies, National Forestry University of Ukraine

Abstract: Modeling of non-isothermal moisture transfer and visco-elastic deformation of wood as a fractal structure. Mathematical model of heat and moisture transfer in wood considering the effects of memory and spatial correlation are synthesized. Explicit and implicit difference schemes for related equations are built. A numerical method predictor-corrector for the implementation of the mathematical model of heat and moisture transfer in wood was introduced.

Keywords: fractal structure, difference schemes, derivatives of fractional order, parallelization, numerical method, approximation

INTRODUCTION Development of adequate mathematical models of viscoelastic deformation and non- isothermal moisture transfer in wood as a environments with fractal structure which is characterized by memory effect, spatial non-locality and self-involved is an actual scientific task. The fractal structure of material may be taken into account by using integral-differential operators of fractional order. The equations with fractional derivative by time describes the effects of memory or non-Markovity process of modeling. Fractional derivatives by spatial coordinates reflect the self-similar heterogeneity of wood. In addition, using equations which contain the differential of fractional order to construct mathematical models of viscoelastic deformation allows more adequately generalize experimental data to identify the model parameters on the basis of physical considerations.

MATERIALS The mathematical model of the distribution of temperature-humidity fields in wood is described by a system of differential equations in partial derivatives of fractional order by time τ and spatial coordinates x1 and x2 : ∂α T ∂ β T ∂ β T ∂αU cρ α = λ1 β + λ2 β + ερ 0 r α ; (1) ∂τ ∂x1 ∂x2 ∂τ ∂αU ∂ βU ∂ βU ∂ β T ∂ β T α = a1 β + a2 β + a1δ β + a2δ β , (2) ∂τ ∂x1 ∂x2 ∂x1 ∂x2 and appropriate initial conditions T(τ x ,, x ) = T (x , x ); 1 2 τ =0 0 1 2 (3) U τ x ,, x = U x , x ; ()1 2 τ =0 0 ()1 2 and boundary conditions of third kind

130 γ ∂ T(τ , x1 , x2 ) λ1 + ρ0 ()()1− ε β1 (U τ , x1 , x2 −U p )= α1 (T ()τ , x1 , x2 − tc ); (4) γ x1 =0 x1 =0 ∂x1 x1 =0 γ γ ∂ T(τ , x1 , x2 ) ∂ U (τ , x1 , x2 ) a1δ + a1 = β1 (U p −U ()τ , x1 , x2 ); (5) γ γ x1 =0 ∂x1 ∂x1 x1 =0 x1 =0 γ ∂ T(τ , x1 , x2 ) λ1 + ρ0 ()()1− ε β1 (U τ , x1 , x2 −U p )= α1 (T()τ , x1 , x2 − tc ); (6) γ =lx 11 =lx 11 ∂x1 =lx 11 γ γ ∂ T(τ , x1 , x2 ) ∂ U (τ , x1 , x2 ) a1δ + a1 = β1 (U p −U ()τ , x1 , x2 ); (7) γ γ =lx 11 ∂x1 ∂x1 =lx 11 =lx 11 γ ∂ T(τ , x1 , x2 ) λ2 + ρ0 ()()1− ε β 2 (U τ , x1 , x2 −U p )= α 2 (T ()τ , x1 , x2 − tc ); (8) γ x2 =0 x2 =0 ∂x2 x2 =0 γ γ ∂ T (τ , x1 , x2 ) ∂ U (τ , x1 , x2 ) a2δ + a2 = β 2 (U p −U ()τ , x1 , x2 ); (9) γ γ x2 =0 ∂x2 ∂x2 x2 =0 x2 =0 γ ∂ T (τ , x1 , x2 ) λ2 + ρ 0 ()()1− ε β 2 (U τ , x1 , x2 −U p )= α1 (T ()τ , x1 , x2 − tc ); (10) γ =lx 22 =lx 22 ∂x2 =lx 22 γ γ ∂ T (τ , x1 , x2 ) ∂ U (τ , x1 , x2 ) a2δ + a2 = β 2 (U p −U ()τ , x1 , x2 ); (11) γ γ =lx 22 ∂x2 ∂x2 =lx 22 =lx 22

where, T - temperature, U - humidity, c - thermal capacity, ρ - density, ρ 0 - base density, ε - phase transition coefficient, r - heat of vaporization, λi - coefficients of thermal conductivity, ai - coefficients of humidity conductivity, δ - thermogradient coefficient, tc - ambient temperature, U p - relative humidity of the environment, α i - heat transfer coefficient, β i - moisture transfer coefficient, α - fractional order of derivative by the time (0 < α ≤ 1), β ,γ - fractional order of the derivative by the spatial coordinates (1 < β ≤ 2), (0 < γ ≤ 1). To simulate the stress-strain state wood during drying the components of displacement T T vector u = (u1,u2 ) and stresses σ = (σ11,σ 22 ,σ12 ) that satisfy the equation of equilibrium should be found: TσB = 0 (11)  ∂ ∂  0 ∂x ∂x  where BT =  1 2  . ∂ ∂  0     ∂x2 ∂x1  Boundary conditions which take into account the symmetry of the problem area and absence of external forces applied to the material are the following:

ui = ;0 σii = .0 (12) xi =0 =lx ii T The correlation between displacements and vector of deformations ε = (ε11 ,ε 22 ,ε12 ) is follows: ε =Bu (13) The relations between stress and deformation components of wood during the process of drying considering it’s fractal structure are based on differential equations of viscoelastic and are determined by formulas:

131 t σ t)( = C R t τ ε t)(),( − ε t)( dτ α (14) ∫ ()T 0

ε T1  α1∆T + β1∆U  where εT = ε T 2  = α 2 ∆T + β 2 ∆U  is vector of deformation caused by varying 0  0  gradients of temperature ∆T and moisture content ∆U respectively. For an anisotropic body, in case of plane stress-deformable state, the matrix of elasticity takes the following form:  E ν E  11 1 22 0 1 −ν ν 1 −ν ν   21 21  ν E E C =  1 22 22 0  (15) 1 −ν ν 21 1 −ν ν 21   0 0 µ     

Here E11 , E22 - Young's modulus, ν 1 , ν 2 - Poisson's coefficients, µ - shear modulus. Also the following initial conditions were added: σ = ;0 ε = .0 (16) ij τ =0 ij τ =0

Taking into account the Riemann-Liouville’s and Grunwald-Letnikov’s formulas we obtain an implicit (ν =1) and explicit (ν = 0 ) difference schemes for the numerical implementation of differential equations (1), (2): T k +1 − αT k λ n λ m U k +1 − αU k сρ ,mn ,mn = 1 Tq k 1−+ ν + 2 Tq k 1−+ ν + ερ r ,mn ,mn ; (17) α β ∑ +− ,1 mjnj β ∑ , jmnj +− 1 0 α Γ()2 − α ∆τ h1 j=0 h2 j=0 Γ()2 − α ∆τ U k +1 − αU k a n a m a δ n ,mn ,mn = 1 q U k 1−+ ν + 2 q U k 1−+ ν + 1 Tq k 1−+ ν + α β ∑ +− ,1 mjnj β ∑ , jmnj +− 1 β ∑ +− ,1 mjnj Γ()2 − α ∆τ h j=0 h j=0 h j=0 1 2 1 (18) a δ m + 2 Tq k 1−+ ν . β ∑ , jmnj +− 1 h2 j=0 To find the numerical solution of the problem predictor-corrector method was used. As a predictor we use an explicit difference scheme and an implicit difference scheme is treated as a proofreader. At the first half-step interval ∆τ 2/ we can write the implicit difference scheme for equation (17) in which only derivative of the fractional order β by the spatial coordinate x1 is taken into consideration: 1 1 k+ 4 k + 4 k αcρ k U n = ATn + αU n − Tn + Ψ 1 (19) ερ 0 r T  α1 tc α1tc  where Ψ1 = U p − 0, ,..., ,0 U p −   ρ0 ()1− ε β1 ρ 0 ()1− ε β1 

and the components aij , , ji = ,1 N of matrix A determined by expressions:

132  ,0 j ≥ i + ;2   α   1    − B1 , i = j = N;   ρ 0 ()1 − ε β1   ,0 i = N 1, ≤ j ≤ N − ;2 − B * , i = ,1 j = ;2  1 a =  cρ  ij   − qA , i = j ≠ 1 ≠ N;   11   ερ 0 r   B γ , i = N , j = N − ;1  1  α *    1 + B*γ , i = j = ;1   ρ ()1 − ε β * 1    0 1   − 1qA ji +− 1 , other.

λ1 * λ1 where B1 = γ , B1 = * γ . ρ0 ()()1− ε β1Γ 2 − γ h1 ρ0 ()()1− ε β1 Γ 2 − γ h1 Similarly equation (18) takes the form: k+ 1 k+ 1 4 4 k BTn + CU n + Ψ 2 + αU n = 0 (20) where  ,0 j ≥ i + ;2   ,0 i = N 1, ≤ j ≤ N − ;2

()qZ 11 − ,1 i = j ≠ 1 ≠ N;  * γ ()a1γ − β1 Γ()2 − γ h1 , i = j = ;1 cij =  γ − a + β Γ 2 − γ h ,i = j = N;  ()1 1 () 1 − a , i = ,1 j = ;2  1 a1γ , i = N, j = N − ;1   1qZ ji +− 1 , other,  ,0 j ≥ i + ;2   ,0 i = N 1, ≤ j ≤ N − ;2  Zq1δ , i = j ≠ 1 ≠ N; bij =  a δγ , i = j = ;1 i = N, j = N − ;1  1 − a δ , i = j = ;iN = ,1 j = ;2  1  Zq ji +− 1δ , other, α a Γ()2 −α ∆τ 1 ( 2) * γ * γ T Z1 = β , Ψ2 = [β1 Γ()()2 − γ h1 U p1 0, ,..., ,0 β1Γ 2 − γ h1 U p1 ] . h1 Having substituted the (19) into (20) we obtain the system of equations which can be solved relatively to the function T and U : k + 1 4 αcρ k k ()B + CA Tn − CTn + ()αC + α U n + Ψ1 + Ψ 2 = 0 (21) ερ 0 r At the second half-step interval ∆τ 2/ we use the implicit difference scheme in which we take into account only the derivative of the fractional order β by the spatial coordinate x2 . As the result we get a set of the solution according to the function T and U . To find the solutions across the range ∆τ we use the corrector which is implemented in the explicit difference scheme:

133 k +1 k n m k +1 k T −αT λ k+ 1 λ k + 1 U −αU сρ ,mn ,mn = 1 Tq 2 + 2 Tq 2 + ερ r ,mn ,mn , (22) α β ∑ +− ,1 mjnj β ∑ , jmnj +− 1 0 α Γ()2 −α ∆τ h1 j=0 h2 j=0 Γ()2 −α ∆τ k +1 k n m n U − αU a k + 1 a k + 1 a δ k + 1 ,mn ,mn = 1 q U 2 + 2 q U 2 + 1 Tq 2 + α β ∑ +− ,1 mjnj β ∑ , jmnj +− 1 β ∑ +− ,1 mjnj Γ()2 − α ∆τ h h h 1 j=0 2 j=0 1 j=0 (23) m a δ k + 1 + 2 Tq 2 β ∑ , jmnj +− 1 h2 j=0 Determination of the visco-elastic properties of wood was carried by acoustic method. The range of problems which are related to an establishment of wood strength properties regular dependence with the parameters of ultrasonic waves taking into account temperature and humidity of a material have been considered. Mathematical models of ultrasonic waves distribution in a wood as the non-isotropic elastic material are synthesized, which was done taking into account its viscoelastic properties. New methods for ultrasonic waves' speed of spreading in wood determination are developed and patented. The corresponding methodology developed. Also the appliance and equipment developed for ultrasonic examinations which allowed ensuring a possibility of carrying out of the experimental acoustic studies in a wide spectrum of the moisture and temperature conditions. On the basis of estimated dependences between the ultrasonic wave speed of spreading and wood strength properties, the new acoustic method for qualimetry of wood assorting by its strengths for coniferous and a hardwood species on structural function of rectangular cut is developed.

RESULTS The statistical analysis of the experimental results allowed to obtain the dependence of the third order regression with the coefficient of multiple determination R 2 = 0,9985 . 2 3 3 3 2 3 c = b0 + b1 ⋅W + b2 ⋅W + b3 ⋅W + b4 ⋅T + b5 ⋅W ⋅T + b6 ⋅W ⋅T (24) b = 1303,52;b = -12,04;b = 0,1132;b = -0,0004; where: 0 1 2 3 b4 = -0,0005;b5 = 8,89E - 06;b6 = -7,86E - 08; Previous investigations make it possible to establish the dependence of the elastic moduli tensor component с55 from the changes in temperature and moisture content for the pine wood. Using the established patterns of connection between the speed of acoustic waves and elastic moduli сαβ it is possible to identify other components of the elastic moduli tensor.

Further we will continue to record с55 = G13 as G13 .

Figure 1. The dependence of SAO (VLT) from changes in temperature and moisture content for pine wood (acoustic method of free oscillations)

134

Figure 2. The dependence of the shear modulus G13 from the changes in temperature and moisture content of pine wood.

It was conducted the numerical calculation of the temperature and moisture fields and components of stress and deformation tensor during drying materials with fractal structure. As the material was selected oak, with an initial value of moisture content u0 = 4.0 kg/kg, 0 0 temperature T0 = 40 C and ambient temperature tc = 70 C . The fractality parameter of this material with the above values of temperature and moisture content were found by approximating the experimental data of creep of oak. It will be equal α = .0 9263 . Let’s show the value of stress and strain tensor components in points: A )0;0( ,

lB 1 ;2/( l2 )2/ and llC 21 );( depending on the time and show the influence of material fractality on them. Figure 3 shows the value of stress components σ11 depending on the time at different points in the cross-section of the bar.

A) B)

Figure 3. The value of stress components σ11 depending on the time at different points in the cross-section of

the bar: А) A )0;0( ; B) lB 1 ;2/( l2 )2/ .

135 CONCLUSION Using the mathematical tools of integration and differentiation of fractional order for the modelling of heat and mass transfer and stress-strain state in capillary-porous materials with fractal structure in comparison with the traditional methods allows us to account the effect of "memory" of the environment and the complex nature of spatial correlations. The finite-difference approximation of differential equations of fractional order with boundary conditions of the third kind was obtained. The algorithmic aspects of their implementation on the basis of using the predictor-corrector method was showed and the conditions of stability of difference algorithms were described. The change of temperature and moisture in wood during drying obtained by implementing mathematical models with taking into account the environment fractal structure in comparison with the traditional models was analyzed. Mathematical model of acoustic wave spreading in the wood as an orthotropic elastic material allows to determine the wood elastic moduli tensor coefficients taking into account the variable temperature and humidity environmental conditions with the purpose to measure the velocity of acoustic oscillations. To assess the influence of viscoelastic wood properties a new mathematical model of the acoustic waves spreading in the wood has been developed. The kernel of wood relaxation is taken into account in the model in exponential form.

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1. Povstenko Y. Z. Stresses exerted by a source of diffusion in a case of a non-parabolic diffusion equation / Y. Z. Povstenko // International Journal of Engineering Science, 43 (2005) . – P. 977-991. 2. Samko S.G. Integralyi i proizvodnyie drobnogo poryadka i nekotorie ih prilozheniya / S. G.Samko, A. A. Kilbas, O. I. Marichev. Minsk:Nauka i tehnika, 1987. – 688 p. 3. Sokolovskyy Ya. Fraktalna model teplo- ta maso perenesennia u kapiliarno-porystykh materialakh / Ya. Sokolovskyy, V. Shymanskyi // Visnyk NU „LP”: Komp’iuterni nauky ta informatsiini tekhnolohii. – Lviv: NU „Lvivska politekhnika”. – 2011, № 694. – P. 424-428. 4. Sokolovskyy Ya. I. Mathematical modeling of timber elastic-viscous-plastic deformation on the drying process / Ya. Sokolovskyy, I. Kroshnyy, Yu. Prusak // Lesotehnicheskiy zhurnal // Vooronezh, 2014, №2 .- . P .166 - 177. 5. Sokolovskyy Ya. I. Matematychne modeliuvannia teplomasoobminnykh protsesiv z vykorystanniam pokhidnykh drobovoho poriadku / Ya. I. Sokolovskyy, M. V. Moskvitina, A. V. Nechepurenko, I. B. Boretska, S. B. Pobereiko // X Mizhnarodna naukovo-praktychna konferentsiia «Matematychne ta imitatsiine modeliuvannia system» (MODS 2015), Chernihiv. – P. 45-49. 6. Sokolowskyi Ya. Mathematical modelling of non-isothermal moisture transfer and rheological behavior in cappilary-porous materials with fractal structure during drying / Ya. Sokolowskyi, V. Shymanskyi // Computer and Information Science. – Canadian Center of Science and Education – Vol. 7, No. 4. – 2014. – P. 111-122. 7. Sokolovskiy Ya. I. Teoreticheskie i eksperimentalnyie issledovaniya opredeleniya anizotropnyih mehanicheskih harakteristik drevesinyi akusticheskim sposobom / Ya. I. Sokolovskiy, O.L. Storozhuk // Sbornik nauchnyih trudov VGLTA, Voronezh, 2013, №5 .- P. 145-153.

136 Streszczenie: Modelowanie nieizotermicznego transferu wilgotności i lepkosprężystej deformacji drewna jako struktury fraktalnej. Opisano modele matematyczne przewodzenia ciepła oraz wilgotności uwzględniając efekt pamięci oraz korelację przestrzenną. Zaproponowano metodę numeryczną implementacji modelu matematycznego transferu ciepła i wilgotności w drewnie.

Corresponding author:

Yaroslav Sokolovskyy, 103, General Chuprynka Str., Lviv, UKRAINE, email: [email protected] phone:

137 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 138-144 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The effect of selected factors on elastic deformation

TOMÁŠ SVOBODA, VOJTĚCH VOKATÝ, VLADIMÍR ZÁBORSKÝ Department of Wood Processing, Czech University of Life Sciences in Prague, Kamýcká 1176, Praha 6 - Suchdol, 16521 Czech Republic

Abstract: The effect of selected factors on elastic deformation. This article is aimed at determining the effect of the wood species (Beech - Fagus Silvatica, Aspen -Populus Tremula L), the thickness of samples used (4, 6, 10, 18 mm), the degree of densification of the wood (10% and 20%) and cyclic loading (0 or 10 000 cycles) on the evaluated characteristic. Significant factors affecting the values of elastic deformation are the wood species, thickness and number of cycles. Densification has no significant effect on the elastic deformation. In regular Aspen wood and Aspen wood subjected to cyclic loading there is a visible transition between 4 mm and 6 mm specimens; in Beechwood this applies to specimens between 6 mm and 10 mm.

Keywords: Cyclic loading, wood densification, Beech, Aspen, elastic deformation

INTRODUCTION:

The mechanical properties of wood are closely related to the wood density. The low density of light wood such as Aspen (Populus Tremula L.) limits the application of the wood where durability and strength is required. However, there is an abundance of low-density wood species in our country, and they can be regarded as cheap wood material. In wood-based materials, unlike real wood, we can control the level of anisotropy, such as the size and orientation of wood particles. This is the significant advantage of these materials; we can control their properties in different areas as required for the end use. If we can improve the mechanical properties of the mentioned low-density wood species, they could be considered an interesting raw material source. Beech (Fagus sylvatica) is the most common hardwood in the Czech Republic. Every year almost one million cubic meters of beech is logged, and we expect an increase in this trend. The demand for this kind of wood in the market still exceeds the supply. Beechwood is largely used as firewood. One way to increase the versatility of the use of wood for purposes other than fuel is by densification. The woodworking industry is constantly searching for new technologies to reduce the undesirable properties of wood and expand its use in non-traditional ways (Kurjatko et al. 2010). Mechanical methods for changing the basic properties of wood include densification. Densification of wood is a modifying technology where the wood is pressed, e.g. by rolling, which reduces its volume and increases its density (Kamke 2006). This technology is also used in construction, but it is primarily used in the furniture industry (Gaff and Gašparík, 2015; Kurjatko et al. 2010; Blomberg and Persson 2007; Laine et al 2013). By densifying wood we can achieve a qualitative change in its properties and gain a material with improved characteristics (Blomberg et al., 2005). The resulting product is characterized by improved physical and mechanical properties in comparison with solid wood, which increases the scope of its use in the production of finished products for various purposes (Kurjatko et al. 2010; Zemiar et al. 2011; Fang et al. 2012).

138 Wood species used (Beech - Fagus Silvatica, Aspen -Populus Tremula L), thickness of the samples used (4, 6, 10, 18 mm), degree of densification of the wood (10% and 20%) and cyclic loading (0 or 10 000 cycles), were the main factors in course of the monitoring. The monitored characteristic was elastic deformation.

EXPERIMENTAL

Materials Beechwood (Fagus Silvatica L.) and Aspen wood (Populus tremula L.) from the Polana region in Slovakia was used for the preparation of test specimens. The selected wood species were used to produce lamellas with a thickness of 4, 6, 10, and 18 mm, a width of 35 mm and a length of 600 mm. The samples were dried to a moisture content of 8% in a climatic chamber at 40% relative humidity and a temperature of 20° C. In these prepared test specimens we found: ‹ The elastic energy during the bending of wood lamellas before cyclic loading (number of cycles = 0) and after cyclic loading (number of cycles = 10 000). We compared the results with results measured in test specimens that were subjected to 10% and 20% densification. 10 test samples were used for each set of test specimens.

Methods

Densification of test specimens Test specimens intended for densification were pressed in a hydraulic press (RK Prüfsysteme MFL 1000, Germany). The densification process of each set of test specimens is shown in Fig. 1.

2800 4800 2600 4500 2400 4200 3900 2200 3600 2000 3300 1800 3000 1600 2700 1400 2400 2100 1200 pressure [kN] pressure pressure [kN] pressure 1800 1000 1500 800 1200 BK-4-10 % 600 O-4-10% 900 B-6-10% 400 O-6-10% 600 B-10-10% O-10-10% 200 300 B-18-10% O-18-10% 0 B-4-20% 0 O-4-20% 012345678910 B-6-20% 012345678910 O-6-20% B-10-20% O-10-20% time [min] time [min] O-18-20% B-18-20% Fig. 1. The principle of the densification of each set of test specimens Determination of bending strength and modulus of elasticity = After the cyclic loading, the support span was adjusted to L1 20× h (support span was changed in relation to thickness of material combinations). The samples were bent in middle- length distance using a universal testing machine FPZ 100 (TIRA, Germany) in accordance with EN 310 (1993). The loading speed was set to 3 mm/min so that the test duration would not exceed 2 min. Maximum breaking forces of samples were measured using the datalogger ALMEMO 2690-8 (Ahlborn GmbH, Germany).

139 Evaluation and Calculation To determine the influence of the individual factors on the bending characteristics, analysis of variance (ANOVA) and the Fischer F-test were performed using the Statistica 12 (Statsoft Inc., USA) software. The modulus of elasticity was calculated in accordance with EN 310 (1993). The conversion of the modulus of elasticity to the moisture content of 12% was performed according to ISO 13061-4 (2014) . The bending strength was calculated in accordance with EN 310 (1993). The bending strength values were converted to the moisture content of 12% in accordance with ISO 13061-3 (2014). The elastic deformation energy was calculated according to equation (1), σ 2 = WP *V0 2* E (1) The wood density was determined before and after testing according to ISO 13061-2 (2014). The moisture content of samples was determined and verified before and after testing. These calculations were carried out according to ISO 13061-1 (2014). Drying to oven-dry state was also carried out according to ISO 13061-1 (2014).

Cyclic bend loading The cyclic loading was carried out on a cycler machine with cyclic bending of the test pieces using single-axis loading. The following numbers of cycles were selected for testing: 0 and 10,000. During the preliminary experimental testing, the test pieces were loaded with static bending to determine the breaking strength and proportional limit because the test pieces had to be loaded up to 90% of the proportionality limit.

RESULTS AND DISCUSSION

Table 1 shows the average values of the elastic deformation energy as well as the corresponding coefficient of variation for each monitored set of density samples.

Table 1. Average values of monitored characteristics and the corresponding coefficient of variation.

MT DD W Cv Density Cv MT DD W Cv Density Cv WS NC P WS NC P (mm) (%) (J) (%) (Kg/m3) (%) (mm) (%) (mm) (%) (Kg/m3) (%)

BK 4 0 0 18 22 693 5 OS 4 0 0 9 30 400 4

BK 4 0 10000 10 43 680 10 OS 4 0 10000 5 18 416 8

BK 4 10 0 26 19 665 3 OS 4 10 0 9 24 533 9

BK 4 10 10000 13 40 692 4 OS 4 10 10000 29 43 539 4

BK 4 20 0 23 23 694 5 OS 4 20 0 15 17 528 4

BK 4 20 10000 37 15 690 6 OS 4 20 10000 19 41 536 8

BK 6 0 0 33 19 735 8 OS 6 0 0 24 27 529 2

BK 6 0 10000 43 23 698 8 OS 6 0 10000 16 22 519 13

BK 6 10 0 16 26 725 9 OS 6 10 0 6 25 421 9

140 BK 6 10 10000 26 12 739 7 OS 6 10 10000 8 75 404 4

BK 6 20 0 19 12 703 5 OS 6 20 0 8 31 557 7

BK 6 20 10000 24 16 749 5 OS 6 20 10000 15 27 584 8

BK 10 0 0 34 14 733 4 OS 10 0 0 10 14 564 1

BK 10 0 10000 33 16 719 6 OS 10 0 10000 20 26 560 6

BK 10 10 0 48 24 744 4 OS 10 10 0 20 29 568 5

BK 10 10 10000 40 16 749 5 OS 10 10 10000 23 18 581 4

BK 10 20 0 10 22 784 4 OS 10 20 0 8 33 488 6

BK 10 20 10000 35 53 766 5 OS 10 20 10000 20 36 476 14

BK 18 0 0 19 26 751 6 OS 18 0 0 21 27 620 10

BK 18 0 10000 21 12 750 5 OS 18 0 10000 16 13 580 6

BK 18 10 0 22 14 788 3 OS 18 10 0 14 27 604 2

BK 18 10 10000 45 18 726 3 OS 18 10 10000 33 28 628 14

BK 18 20 0 36 8 747 7 OS 18 20 0 20 24 589 7

BK 18 20 10000 38 12 757 9 OS 18 20 10000 21 14 594 6

Legend: WS –Wood Samples, Material Thickness, Degree of densify, Number of cycles, WP - Elastic deformation energy,

Table 2. The basic table of statistical characteristics evaluating the effect of individual factors, as well as their two-, three- and four-factor interaction, on the limit of proportionality.

Sum of Degree of Fisher's Significance Monitored factor Variance squares freedom F - Test level P

Intercept 119889.6 1 119889.6 3858.628 0.000001

1) Wood species 7734.5 1 7734.5 248.935 0.000001

2) Material thickness 9026.7 3 3008.9 96.841 0.000001

3) Degree of densification 36.1 2 18.1 0.582 0.560037

4) Number of cycles 1720.0 1 1720.0 55.358 0.000001

1*2*3*4 358.4 6 59.7 1.922 0.079068

Error 5965.5 192 31.1

Tab. 2 shows the statistical significance of the individual factors. The wood species, material thickness and number of cycles were shown to be statistically significant factors. The degree of densification was shown to be a statistically insignificant factor, and the effect of the combination of all four factors was also insignificant.

141 32 35

28 30

25 24

22 20 20

Práca pružnej (J)deformácie Práca 18 pružnejPráca deformácie (J) 15 16

14 Beech Aspen 10 4 6 10 18 W ood species Material thickness (mm)

Fig. 2. The effect of the wood species on the Fig. 3. The effect of the material thickness on Elastic deformation energy the Elastic deformation energy

The effect of wood species on the elastic deformation energy (Fig. 2) shows a difference between beech and aspen wood, where higher average values were measured in beechwood. Figure 3 shows that the material thickness is also a statistically significant factor, where the elastic deformation energy increases with increasing thickness.

26 28

27 25 26

24 25

24 23 23

22 22 21 21 20 Práca pružnejPráca deformácie (J) Práca pružnejPráca deformácie (J) 19 20 18

19 17 0 10 20 0 10000 Degree of densification (%) Number of cycles Fig. 4. The effect of the degree of densification Fig. 5. The effect of the number of cycles on the on the Elastic deformation energy Elastic deformation energy

The only monitored factor that proved to be statistically insignificant is the degree of densification. Figure 4 shows a slight decline in the elastic deformation energy with a higher degree of densification. Figure 5 shows the number of cycles, and it is apparent that the elastic deformation energy increases with the number of cycles.

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60 Faktory: Úrovně 60 Faktory: Úrovně Počet cyklů: 0 Počet cyklů: 10000 56 56 52 52 48 48 44 44 40 40 36 36 32 32 28 28 24 24 20 20 16 16 Práca pružnejPráca deformácie (J) 12 pružnejPráca deformácie (J) 12 8 8 4 4 0 0 MT (mm) 6 18 MT (mm) 6 18 MT (mm) 6 18 MT (mm) 6 18

4 10 4 10 of Degree densification (%) 0 of Degree densification (%) 10 of Degree densification (%) 20 4 10 4 10 of Degree densification (%) 0 of Degree densification (%) 10 of Degree densification (%) 20

Wood species: Beech Wood species: Aspen Wood species: Beech Wood species: Aspen

Fig. 6. The effect of the wood species, degree of Figure 7. The effect of the wood species, degree densification and number of cycles on the of densification and number of cycles on the Elastic deformation energy Elastic deformation energy

It is apparent from Fig. 6 that the elastic deformation values in beechwood not subjected to cyclic loading increase with the increasing thickness along the same lines for all three degrees of densification. This does not apply to aspen wood not subjected to cyclic loading. Non- densified wood increases in an almost linear line, while the values interestingly decrease slightly between 6 and 10 mm in both degrees of densification. In beechwood subjected to cyclic loading (Fig. 7) there is a noticeable increase in values of elastic deformation energy between 6 and 10 mm. In aspen wood subjected to cyclic loading the difference between non-densified wood and wood densified by 10% is between 4 and 6 mm, and in wood densified by 20% the difference is between 6 and 10 mm.

CONCLUSIONS:

The results demonstrate the effect of the selected factors (Wood species, number of loading cycles, material thickness and degree of densification) on the elastic deformation energy. The results constitute an invaluable foundation that is necessary for the further development of wood- based materials. Significant factors affecting the elastic deformation energy are the wood species, thickness and number of cycles. The degree of densification has no significant effect on the elastic deformation energy. The effect of cyclic loading is noticeable in aspen wood specimens with a thickness of 4 mm and 6 mm, and in beechwood specimens with a thickness of 6 mm and 10 mm. Specifically, we can see the transition between 4 mm and 6 mm in regular aspen wood samples and samples subjected to cyclic loading, and between 6 mm and 10 mm in beechwood samples subjected to cyclic loading.

REFERENCES:

1. Blomberg, J., and Persson, B. (2007). “Swelling pressure of semi-isostatically densified wood under different mechanical resraints”, Wood Science and Technology 41(5), 401-415. DOI: 10.1007/s00226-006-0118-1

143 2. Blomberg, J., Persson, B., and Blomberg, A. (2005). “Effects of semi-isostatic densification of wood on thevariation in strength properties in density”,Wood Science and Technology 39(5), 339-350. DOI: 10.1007/s00226-005-0290-8 3. Fang, C. -H., Mariotti, N., Cloutier, A., Koubaa, A., and Blanchet, P. (2012). „Densification of wood veneers by compression combined with heat and steam“, European Journal of Wood and Wood Products 70(1-3), 155-163. DOI: 10.1007/s00107-011-0524-4 4. Gaff, M., and Gašparík, M. (2015). „Influence of densification on bending strenght of laminated beech wood“, BioResources 10(1), 1506-1518. DOI: 10.15376/biores.10.1.1506- 1518 5. Kamke. F.A. (2006). „Densified radiate pine for structural composites“, Maderas. Ciencia y Technología 8(2), 83-92. DOI: 10.4067/S0718-221X2006000200002 6. Kurjatko, S., et al.: Parametre kvality dreva určujúce jeho finálne použitie / Stanislav Kurjatko et al.; rec. Ivan Makovíny, Štefan Šteller. - Zvolen : Technická univerzita vo Zvolene, 2010. - 352 s. : obr., tab. - APVV-0282-06. - ISBN 978-80-228-2095-0 7. Laine, K., Rautkari, L., Hughes, M., and Kutnar, A. (2013). “Reducing the set-recovery of surface densified solid Scots pine wood by hydrothermal post-treatment”, European Journal of Wood and Wood Products 71(1), 17-29. DOI: 10.1007/s00107-012-0647-2 8. Zemiar, J., Zbončák, R., and Gaff, M. (2011). „Thickness changes of cyclical pressed veneer“. In: Annals of Warsaw University of Life Sciences– SGGW. Forestry and Wood Technology No 76. Warsaw University of Life Sciences Press, Warsaw Poland, 218-222. ISSN 1898-5912.

Corresponding authors:

Tomáš Svoboda, Vojtěch Vokatý, Vladimír Záborský 1 Department of Wood Processing, Czech University of Life Sciences in Prague, Kamýcká 1176, Praha 6 - Suchdol, 16521 Czech Republic; *Corresponding author: [email protected]

ACKNOWLEDGEMENT:

The authors are grateful for the support of the IGA Faculty of Forestry and Wood Science at Czech University of Life Sciences Prague grant project, project number B04/16 Principy tvorby lamelových materiálů.

144 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 145-150 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Economic justification for printing threaded joints for wood-based materials

MACIEJ SYDOR, MARCIN WOŁPIUK Poznan University of Life Sciences, Faculty of Wood Technology, Department of Woodworking Machines and Fundamentals of Machine Design

Abstract: Economic justification for printing threaded joints for wood-based materials. Screws are popular elements used to connect wood-based panels. They are typically made of metal, which means that their strength is 10- up to 15-fold greater than that of connected wood materials. The paper presents results of an experiment, in which screws for wood material were produced by 3D printing in the Fused Deposition Modeling (FDM) technology. The aim was to experimentally verify the economic justification for the manufacture of screws by 3D printing.

Keywords: 3D printing screw, economic aspects.

INTRODUCTION

SCREWS FOR WOOD-BASED MATERIALS Built-in furniture, building woodwork as well as building structures made of wood and wood-based materials pose three different engineering challenges: 1) the need to ensure visual attractiveness, 2) high functionality, and 3) adequate structural reliability (Eckelman, 1978). Each of the above-mentioned areas involves connections of individual structural elements. The primary function of connections is to ensure a durable and reliable connection of elements under stable and variable loads. Desirable characteristics of connections include limited price, reliability and easy assembly using commonly available tools. It is particularly desirable when furniture is assembled at the customer’s premises. A popular method to connect wood-based materials is to apply threaded metal joints, particularly various screw types. Their low price and easy assembly are indications for their common use.

Table 1. Popular screw types used to connect wood-based materials Name Drawing Used for Dimensions

Wood screws with oval Diameters 3-6, fillister, button and lentil Wood parts length heads (universal) 12-200 mm

Wood screws with Diameters 5-16, hexagonal heads For large wood elements length

(construction) 25-320 mm Confirmat screws Diameters 5, for wood-based panels (including “euro” screws) 6.3 and 7 mm Diameters 2.5-10 Screws for particleboards For particleboards mm, length 10-400 mm

145 To connect fibre Diameters 3.5-4.8 Drywall screws gypsum boards with mm, length

wood elements 25-140 mm, Conventional screws for wood and wood-based materials are composed of three basic parts: the head, the shank and threads. Each of these parts serves different functions. The head is shaped to facilitate the positioning of the tool for screw assembly. Another function is served by the head bottom locking it in the material. Not all screws have the unthreaded section of the shank. It is used when the screw length is rather big, particularly when it is necessary to press two panel materials together. The shank is the basic part of each screw, its edges produce threads in the hole and planes block the thread cut in the hole with the thread cut in the shank. The most popular materials used to manufacture screws for wood-based materials include austenic stainless steel, with carbon steel, bronzes and aluminum alloys are used. Some screws are made of polymer materials (e.g. composites: polyphthalamide + glass fiber, polymethyl methacrylate or nylon). The most popular screw types are listed in table 1.

3D PRINTING Fused Deposition Modeling (FDM) 3D printers (Pham & Gault, 1998) resemble in their design 3-axis CNC routers, except that the spindle is replaced with the printing head (extruder). Printed models are produced by deposition of melted thermoplastic fibers within the element section (Fig. 1). One head is capable of depositing the material of one color variant. When a printer is equipped with a larger number of heads a printed model of several colors may be produced; however, this is related with higher costs of either the construction or purchase of the machine.

Figure. 1. A diagram for the operation of a 3D printer working in the FDM technology

Recently we have been observing increasing popularity of the OpenSource design of FDM printers named RepRap. This facilitates considerable reductions of costs associated with the introduction of the machine in comparison to commercial solutions (Jones et al., 2011).

MATERIAL AND METHODS It was decided to manufacture confirmat screws in the FDM technology. The experiment was conducted using a RepRap 3D printer (Fig. 2).

146

Fig. 2. The RepRap 3D printer used in the experiment

Basic working parameters of the used printer are given in Table 2.

Table 1. Selected working parameters of RepRap 3D printer Parameter Value Maximum print dimensions 195 × 195 × 150 mm Printing speed Do 100 mm/s Nozzle temperature Do 230°C Power 350 W Resistance of table heater 1,2 Ω Engine step; fixing moment 1,8°; 0,44 Nm Theoretical resolution of X and Y axes 0,02 mm / mikrostep

A previously prepared 3-dimensional virtual model of a confirmat screw (Fig. 3) was divided into 2 parts to simplify the printing operation and to reduce material consumption for the printed supports (Fig. 3b)

Fig. 3. A confirmat screw model: a – whole, b – divided into two parts

147 After optimal printing parameters were established, the 3D model was produced.

RESULTS AND ANALYSIS PRINTING RESULTS 3D prints of the two confirmat halves are given in Fig. 4.

Fig. 4. Printed two halves of the confirmat screw

Both halves were glued producing the finished confirmat screw (fig. 5).

Fig. 5. Both confirmat screw halves glued together to produce the whole

Next the printed joint was screwed. The operation was successful.

ECONOMIC ASPECTS OF PRINTING OPERATIONS Following the successful experiment the costs of purchase of confirmat screws were compared with the manufacturing costs for the printed threaded joint.

Table 2. Estimated costs of 3D printing Parameter Value Remarks Cost of purchase for one metal confirmat ca 0,06 PLN screw Weight of printed confirmat screw 2 g Price of consumed material 0,014 PLN Unit cost of material is approx. 70 PLN/kg Printing time 15 min Energy consumption by working printer ca. 70W Energy consumed for printing one 0,018 kWh confirmat screw Cost of electrical energy for printing of 0,01 PLN Mean price of 1 kWh is 0.57 one confirmat screw PLN Total production costs of one confirmat 0,024 PLN screw

A comparison of material properties of typical materials used in the manufacture of screws and the material, from which screws were made, are given in Table 4.

148 Table 3. A comparison of materials Tensile Modulus Tensile Modulus Remarks and Material Types / species relative to the (GPa)1 references MDF most frequently: Austenitic A2, les frequently 194 4850% – stainless steel A3 C4D-C20D according to ISO Carbon steel 205 5125% – 1006-1021 according to SAE Np. C51000, According to the Bronzes C52100, C54400 110 2750% unified numbering and other system (UNS) 5052, 6061, 6063, Aluminium 2017, 7075 69 1725% – alloys and other Composite (polyphthalamide 17,5 438% – (PPA) 55%, Polymer fiber glass 45%) materials polymethyl methacrylate 1,8-3,1 45-78% – (PMMA) Nylon 2-4 50-100% –

FINAL CONCLUSIONS Considering only the costs of material it seems recommendable to print joints. However, in view of printing time required for one piece as well as the time required for the preparation of the model it is advisable to apply joints produced in this technology only for positions requiring atypical joints or for recyclable products. Joints made from plastics are not elements dangerous for machines used in the recycling of raw materials and - in contrast to their metal equivalents - they do not have to be thoroughly removed from the utilised product.

REFERENCES 1. Eckelman, C. A. (1978). Strength design of furniture. Tim Tech Inc. Retrieved from http://www.agriculture.purdue.edu/fnr/faculty/Eckelman/pdf/pdm0scan.pdf 2. Jones, R., Haufe, P., Sells, E., Iravani, P., Olliver, V., Palmer, C., & Bowyer, A. (2011). RepRap–the replicating rapid prototyper. Robotica, 29(01), 177–191. 3. MatWeb’s services. (2015). Automation Creations. Retrieved from http://www.matweb.com/ 4. Pham, D., & Gault, R. (1998). A comparison of rapid prototyping technologies. International Journal of Machine Tools and Manufacture, 38(10), 1257–1287. 5. PN-EN ISO 3506-1. (2009). (Własności mechaniczne części złącznych odpornych na korozję ze stali nierdzewnej -- Część 1: Śruby i śruby dwustronne). 6. PN-M-82509. (1984). (Wkręty do drewna -- Wymagania i badania). 7. Wkręty samogwintujące krzyżakowe. (2014). Moss (Essentra Components). Retrieved from http://www.essentracomponents.pl/wkrety-samogwintujace-krzyzakowe

1 Data modulus of elasticity by (“MatWeb’s services,” 2015).

149 Streszczenie: Ekonomiczny sens drukowania gwintowanych łączników do tworzyw drzewnych. Wkręty są popularnym środkiem do wykonywania połączeń płyt drewnopochodnych. Zwykle wykonuje się je z metalu, co oznacza że ich wytrzymałość jest od 10 do 15 większa od wytrzymałości łączonych materiałów drzewnych. W artykule przedstawiono wyniki eksperymentu polegającego na wykonaniu wkrętów do drewna za pomocą druku 3D techniką FDM (Fused Deposition Modeling). Celem przeprowadzonych działań była eksperymentalna weryfikacja uzasadnienia ekonomicznego wykonywania wkrętów techniką druku 3D.

Corresponding author:

Maciej Sydor, ul. Wojska Polskiego 38/42 60-627 Poznań email: [email protected] phone: (061) 846-6144

Acknowledgements: The authors would like to thank Marcel Grzanka (MSc., Eng.) for making it possible to manufacture test printed screws.

150 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 151-156 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The effect of pitch of thread on the force retaining screws in particleboard

MACIEJ SYDOR, MARCIN WOŁPIUK Poznan University of Life Sciences, Faculty of Wood Technology, Department of Woodworking Machines and Fundamentals of Machine Design

Abstract: The effect of pitch of thread on the force retaining screws in particleboard. The paper presents testing results of the force retaining screws in particleboards. A research hypothesis was proposed that the pitch of thread within the range of 2.5, through 3 to 3.5 mm affects the value of the screw retaining force. Screws with three different pitches of thread were tested when mounted in the wide and narrow plane of the panel. Samples were made according to the guidelines of the ISO Standard 27528:2009. Tests were conducted using a universal strength testing machine. The research hypothesis was not confirmed in these tests.

Keywords: wood screw, pitch, particleboard.

INTRODUCTION Threaded joints, either screwed directly into the connected material or into pilot holes prepared earlier, are used on a mass scale in furniture and construction industries. Although screws are more or less two or three times more expensive than nails, they have two significant advantages over the later , i.e. markedly greater pullout resistance and easy disassembly. Screws for wood-based materials are standardized to a very limited degree. To date no ISO standards have been developed for wood screws. These joints are specified in very few national standards (e.g. Polish PN or German DIN) (Sydor, 2016). Despite a lack of standardization most designs of screws are produced by various manufacturers in identical or almost identical design forms and in comparable series of types. Forms of these screws constitute the so-called de facto standards1 . An example of the very popular non-standardized screw is the confirmat screw developed in the 1970’s by Häfele (fig. 1).

Figure 1. The structural form of a confirmat screw

1 A de facto standard is a concept, which was not acknowledged by any formal standardization organisation, but proved to be so practical that it is imitated and used extensively by other manufacturers.

151

It is a screw dedicated for connections of furniture panels, particularly particleboards. Table 1. Dimensions of confirmat screws Diameter D Diameter D2 Pitch P Length L 5 3,5 2,6 38, 50 6,3 4 3 50 7 4 3 38-75 (based on (“Produkte werkstatt für und montage. Werkzeugs,” 2014))

Most commonly used confirmat screws are those with D = 7 mm with pitch of thread P = 3 mm. Such screws, similarly as other screws for materials of low strength in comparison to that of a metal joint, has an increased groove width between threads in comparison to that of the thread width. Research hypothesis: The pitch of thread has an effect on the value of the force retaining confirmat screws in particleboard. An increase in its value will increase the value of this force.

MATERIALS AND METHODS MATERIALS It was decided to use particleboard of 18 mm in thickness in this test. The distribution of density at the panel section used in the test was non-uniform, which makes it possible to assume that the tested particleboard has a 3-layer structure (fig. 1). Averaged material properties of the two face layers (with approximate thickness of 2 mm) were identical, while the core of the panel, of lower density, had markedly different material properties.

Figure. 2. A model for a 3-layer wood-based board (based on (Sydor & Wołpiuk, 2016))

Numerical values of material properties of the particleboard used to prepare testing samples are given in Table 1.

Table 2. Physical properties of particleboard Parameters Denomination Face layer Core layer Thickness t (mm) 18,0 ±0,2 Humidity ϕ (%) 7,7 (1,1) 661,5 (158,6) Density ρ (kg/m3) 867,4 (150,7) 591,4 (81,0)

Young's modulus Ex (GPa) 4,43 (0,47) 1,82 (0,14)

(EN 310) Ey (GPa) 3,82 (0,33) 1,59 (0,20)

152 Ez (GPa) 0,49 (0,06) 0,23 (0,02) Numbers in parentheses represent standard deviations Tests were conducted on three screws prepared by the authors, differing in the pitch of thread: a screw with the pitch of thread 2.5, with the pitch of thread 3.0 and with the pitch of thread 3.5 mm, respectively. The most important dimensions of the screws are given in fig. 3.

Screw No Pitch P (mm) Lp (mm) 1 2,5 2,5 2 3,0 3,0 3 3,5 3,5 Figure. 3. Screws used in tests

Variation in the pitch of thread (P) is manifested in the variation of the groove width of the screw. Width of the crest of the thread (T) for all the three screws is 1.24 mm, while the width of the crest for the internal thread (cut in the board) ranged from 1.26 to 2.26. Since screws automatically produce internal threads in the pilot hole, threads of screws with a larger pitch of thread include internal threads of greater thickness. This can be seen in fig. 4, where for the pitch of thread P = 2.5 the width of the screw cap is 102% screw width, while for the pitch of thread P = 3.5 – the width of the screw cap is 182% width of the screw.

Figure. 4. Variation of groove width depending on the pitch of thread

153

Screws were mounted in the narrow and wide planes of the panel to a depth of 15 mm (fig. 5).

Figure. 5. Position of screws in the sample

A total of 54 samples were prepared (two sides of the panel, three screw types, nine replications, i.e. 2×3×9=54).

METHODS

Pullout tests were performed using a Zwick Z050 universal strength machine applying the following parameters: • Initial force: 5 N, • After the initial force was obtained, screws were pulled at a rate of 2 mm/min.

During the experiment the force retaining screws in the panel was recorded depending on the translocation (removal of the pulled screw from the hole). Based on the performed nine replications for each series the following values were calculated: the mean value, standard deviation and the error mean.

RESULTS AND DISCUSSION

Testing results included measured forces retaining screws in the board in relation to the depth of the screw position. Results are presented in two graphs: fig. 6 for measurements taken for the narrow plane, and fig. 7 or measurements taken for the wide plane, respectively.

154 Withdrawal capacity to the limit of proportionality 100 Withdrawal capacity to the 90 maximum force 80

70 62 57 60 53 50 42 38 40 37 Force (N/mm) Force 30

0 2.5 3 3.5 Thread pitch (mm)

Figure. 6. Measurements of the force retaining screws in the narrow plane of panel

Withdrawal capacity to the limit of proportionality 100 Withdrawal capacity to the 90 84 maximum force 78 80 73

70 58 60 50 45 44 40 Force (N/mm) Force 30 20 10 0 2.5 3 3.5 Thread pitch (mm) Figure. 7. Measurements of the force retaining screws in the wide plane of panel

CONCLUSION The aim of this study was to determine the effect of changes in the pitch of thread for screws pulled out from the narrow and wide planes of the particleboard. It was hypothesized that an increase in the pitch of thread (i.e. simultaneously increasing groove width) in screws will increase the capacity to counter axial pullout. The adopted hypothesis was not confirmed.

It was stated that: 1. In the case of pullout from the narrow plane the value of the pullout force decreases with an increase in the pitch of thread. 2. In the case of the wide plane a change in the pitch of thread within the range of 2.5-3 mm had no significant effect on the value of the force retaining screws in particleboard.

155 REFERENCES

1. Produkte werkstatt für und montage. Werkzeugs. (2014). Häfele. Retrieved from www.haefele.de/is-bin/intershop.static/WFS/HDE-EasyLink_HDE-Site/HDE- EasyLink_HDE/de_DE/pdfcatalog/MT2013/index.html?startpage=1.23?SessionId=&c lientID=HDE&locale=de_DE¤cy=EUR&useClipboard=true 2. Sydor, M. (2016). Innowacje w zakresie łączników gwintowych do tworzyw drzewnych. Fastener. Rynek Elementów Złącznych (Dodatek Do STAL Metale& Nowe Technologie), (1/2016), 35–38. 3. Sydor, M., & Wołpiuk, M. (2016). Analysis of resistance to axial withdrawal of screws embedded in locally reinforced MDF. Drewno, 59(196), 173–182. http://doi.org/DOI: 10.12841/wood.1644-3985.093.14

Streszczenie: Wpływ skoku gwintu na siłę utrzymującą wkręty w płycie wiórowej W artykule zamieszczono wyniki badań siły utrzymującej wkręty w płycie wiórowej. Postawiono hipotezę badawczą, że skok gwintu w zakresie od 2,5, przez 3 do 3,5 mm wpływa na wartość siły utrzymującej wkręty. Badano wkręty o trzech różnych skokach gwintu osadzone w szerokiej i wąskiej powierzchni płyty. Próbki wykonano według wytycznych normy ISO 27528:2009. Badania przeprowadzono za pomocą uniwersalnej maszyny wytrzymałościowej. W wyniku badań nie potwierdzono hipotezy badawczej.

Corresponding author: Maciej Sydor, ul. Wojska Polskiego 38/42 60-627 Poznań email: [email protected] phone: (061) 846-6144

156 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 157-161 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Modulus of elasticity at static bending in selected provenances of Norway spruce (Picea abies [L.] Karst)

JAROSŁAW SZABAN1, WOJCIECH KOWALKOWSKI2 , MARCIN JAKUBOWSKI1, TOMASZ JELONEK1, ARKADIUSZ TOMCZAK1, KAMILA PŁOŃSKA1 Poznan University of Life Sciences. Departament of Forest Utilisation1, Departament of Silviculture2

Keywords: Norway spruce, provenance, modulus of elasticity

Abstract: Modulus of elasticity at static bending in selected provenances of Norway spruce (Picea abies [L.] Karst. The paper presents research results concerning the effect of provenance on modulus of elasticity of wood at static bending. Material for analyses was collected from a unique experimental site of the Department of Silviculture, the Poznan University of Life Sciences. The experimental site is located at the Siemianice Forestry Experimental Station. A total of 20 best provenances of Norway spruce were planted at the site in several replications. It may be assumed that the investigated spruce populations were growing under very similar environmental conditions. From twenty provenances growing at the experimental site seven were selected for analyses: Zwierzyniec Białowieski, Międzygórze, Istebna Bukowiec, Orawa, Zwierzyniec Lubelski, Kartuzy and Nowe Ramuki. Experimental material in the form of rollers was collected at breast height from the provenances selected for analyses. Results show the effect of provenance on the modulus of elasticity in spruce wood. It was also determined which of the investigated provenances have wood with the best modulus of elasticity at static bending.

INTRODUCTION Variation in technical properties of wood within a species depends on many factors. It may be assumed that this variation will be found particularly in the species with diverse geographical ranges. An example of such a species in Poland is e.g. Norway spruce (Picea abies L. Karst). Two geographical ranges of this species run through Poland and they are separated by the so- called spruce-free belt, as a result growth conditions for spruce vary in different parts of the country (Białobok 1977, Boratyński Bugała 1998). Although this species has recently experienced a certain regression, it is still considered to be of interest by foresters e.g. due to its considerable growth potential (Barzdajn et al. 2003, Puchniarski 2008). In Poland specific provenances should not be transferred outside their ranges, although this limitation does not apply to plantation culture of trees within a short production cycle, to which spruce is well- adapted (Michalec 2007). The dependence of technical properties of spruce wood, which is frequently used as structural material, on its provenance is crucial particularly in view of the observed timber deficit. The aim of this study was to compare the modulus of elasticity at static bending for spruce wood coming from trees representing 7 different provenances: Zwierzyniec Białowieski, Międzygórze, Istebna Bukowiec, Orawa, Zwierzyniec Lubelski, Kartuzy and Nowe Ramuki. The experimental site, on which the investigated provenances were growing, is unique in character and studies concerning the effect of provenance on tree characteristics have been conducted there for many years. It is crucial here that these provenances were growing at the experimental site with similar growth conditions and possible differences in technical properties of wood of individual provenances may result from genetic factors. Only in the case of an experimental site we may determine the actual effect of genetic factors on technical properties of wood (Siek 1970, Barzdajn 2003, Sofletea et al. 2012, Szaban et al. 2014). It was assumed in this study that provenance of Norway spruce has an effect on modulus of elasticity at static bending.

157 METHODS Material for analyses was collected from the experimental site of the Department of Silviculture, the Poznan University of Life Sciences. The experimental site was established in 1975 at the Siemianice Forestry Experimental Station in the Laski Forest District. Spruces representing 20 different provenances were planted at the experimental site. The site comprised five blocks (belts), with 20 provenances distributed randomly in each. In 2012 material for analyses in the form of blocks were collected at breast height. Seven provenances found in different regions of Poland were selected for analysis. Trees for analyses were selected based on the dendrometric Urich II method (Grochowski 1973). A total of 12 trees were collected from each provenance. Prior to felling the north direction was marked on the selected trees. Next the material was converted at a sawmill and samples for strength testing in accordance with the standard PN63/D04117 were collected. From each roller a board oriented in the north- south direction was cut. After boards were sawn, battens of 2 cm x 2 cm were cut, from which in turn samples of 2 x 2 x 30 cm were collected. Samples were taken only from the circumferential section, rejecting the pith section containing juvenile wood (Kokociński 2004). Laboratory analyses were conducted using a Tira test 2300 strength testing machine. Statistical calculations were performed with the use of Microsoft Office Excel 2010 and Statistica 10 software.

RESULTS AND DISCUSSION The primary objective of this study was to verify whether the investigated provenances differ in terms of the analysed trait. In this case the analysis of variance was conducted, which showed differences between the investigated populations (provenances). Statistical analysis also showed that the lowest mean value of the investigated trait was recorded for provenance 6 (Nowe Ramuki), while it was highest for provenance 19 (Zwierzyniec Lubelski). Standard deviation ranged from 781 for provenance 6 (Nowe Ramuki) to 1064 for provenance 11 (Istebna). Also the median values for individual provenances showed a similar dependence, assuming the lowest value for provenance 6 and the highest for provenance 11. The lowest value of the analysed index was found for a sample from provenance 6, while the highest value was recorded for samples coming from trees of provenances 19 and 21 (tab. 1).

Table 1. Descriptive statistics

Average N Amount Std dev. Std. error Min Max Q25 Median Q75 coef. of var provenances MOE MOE MOE MOE MOE MOE MOE MOE MOE MOE % 1 4196 44 184641 891 134 2442 6500 3707 3992 4619 21,2 6 3939 51 200888 781 109 2076 5544 3465 3839 4586 19,8 8 4159 46 191325 855 126 2816 5670 3478 4113 4709 20,6 11 4197 41 172087 1064 166 2265 6819 3520 4142 4959 25,4 16 4035 50 201745 921 130 2291 6026 3282 4108 4691 22,8 19 4572 47 214894 1019 149 2285 6950 3792 4612 5203 22,3 21 4396 49 215428 909 130 2478 6056 3719 4402 5170 20,7 Groups 4210 328 1381008 934 52 2076 6950 3509 4141 4909 22,2

When analysing the obtained results based on the mean calculated for all samples (4210 MPa) it was established that populations 1, 6, 8, 11 and 16 received results below the mean, whereas results for provenances 19 and 21 exceeded the mean for all the populations (Fig. 1). Next statistical analysis was conducted to determine, which of the investigated populations differ significantly from one another. The results are presented in a table form (tab. 2) and as a graph (Fig. 2). It was found that population 19 (Zwierzyniec Lubelski) differs significantly from 3 populations (Nowe Ramuki, Międzygórze, Orawa), whereas population 6 (Nowe Ramuki) differs significantly from populations of Zwierzyniec Lubelski and Kartuzy. Populations 21, 16

158 and 8 differ only in relation to one population. The analysis showed that two populations (1 and 11) do not differ from the others (tab.2).

MOE [MPa] 4700 4600 4500 4400 4300 4200 4100 1 6 8 11 16 19 21 4000 3900 3800 3700 3600

Fig. 1 Mean compressive strength values in relation to the mean for all samples

Table 2 The LSD test and a list of differences between analysed provenances (* differences) 1 6 8 11 16 19 21

1 {1} 0,174985 0,848355 0,996571 0,396588 0,052426 0,295896 6 {2} 0,174985 0,240047 0,181883 0,600831 0,000751* 0,013456* 8 {3} 0,848355 0,240047 0,847678 0,508874 0,031229* 0,210120 11 {4} 0,996571 0,181883 0,847678 0,403077 0,057453 0,307100 16 {5} 0,396588 0,600831 0,508874 0,403077 0,004326* 0,051495 19 {6} 0,052426 0,000751* 0,031229* 0,057453 0,004326* 0,350377 21 {7} 0,295896 0,013456* 0,210120 0,307100 0,051495 0,350377

Fig 2 Modulus of elasticity (MOE) – average of the analysed provenances

159 CONCLUSIONS The recorded results make it possible to draw the following conclusions: 1. Provenance studies provide a ranking list of the best Polish provenances in terms of wood strength properties. 2. Among the seven analysed provenances the best modulus of elasticity was recorded for provenance 19 – Zwierzyniec Lubelski, while the parameter was lowest for provenance 8 - Międzygórze. 3. Some of the investigated provenances differ significantly from one another in terms of the mean value of modulus of elasticity. 4. Based on the study it may not be decided why some of the analysed provenances differ significantly from one another. It seems necessary to conduct analyses of wood structure and specify whether there are differences in the microscopic structure of xylem in individual provenances. 5. Provenance sites are formed over long periods of time and are unique in character. For this reason studies on the dependence between provenance and technical properties of wood should be conducted regularly in successive years.

REFERENCES 1. BARZDAJN W. 2003: Świerk pospolity (Picea abies [L.] Karst.) w 30-letnim doświadczeniu proweniencyjnym serii IUFRO 1972 W Nadleśnictwie Doświadczalnym Siemianice. Sylwan 7; 24-30. 2. BARZDAJN W., CEITEL J., MODRZYŃSKI J., 2003: Świerk w lasach polskich – historia, stan, perspektywy, Poznań. 3. BIAŁOBOK S., 1977: Świerk pospolity Picea abies (L.) Karst., Instytut Dendrologii PAN, Państwowe Wydawnictwo Naukowe, Warszawa, Poznań. 4. BORATYŃSKI A., BUGAŁA W., 1998: Biologia świerka pospolitego. Instytut dendrologii PAN Bogucki Wydawnictwo Naukowe, Poznań. 5. GROCHOWSKI J., 1973: Dendrometria. Powszechne Wydawnictwo Rolnicze i Leśne, Warszawa. 6. JAWORSKI A., 2011: Hodowla lasu. Charakterystyka hodowlana drzew i krzewów leśnych. Powszechne Wydawnictwo rolnicze i Leśne, Warszawa. 7. KOKOCINSKI W., 2004: Drewno. Pomiary właściwości fizycznych i mechanicznych. Wyd. Akademia Rolnicza Poznań; 1-201. 8. MICHALEC K., 2007: Jakość surowca świerkowego (Picea abies [L.] Karst) pochodzącego z głównych ośrodków i zasięgów jego występowania w Polsce. Drewno 50 [177]; 57-78. 9. PUCHNIARSKI T., 2008: Świerk pospolity. Hodowla i ochrona. Wyd. EKO- LAS, Warszawa. 10. SIEK M., 1970: Badania porównawcze własności drewna morfologicznych odmian świerka pospolitego. Sylwan 7; 27-32. 11. SOFLETEA N., BUDEANU M., PARNUTA G., 2012: Provenance variation in radial increment and wood characteristic revealed by 30 year old Norway spruce comparative trials. Silvae Genetica 61 [4-5]; 170-178. 12. SZABAN J., KOWALKOWSKI W., KARASZEWSKI Z., JAKUBOWSKI M., 2014: Effect of tree provenance on basic wood density of norway spruce (Picea abies [L.] Karst) grown on an experimental plot at Siemianice Forest Experimental Station. Drewno. Prace Naukowe Doniesienia Komunikaty Vol 57 No 191; 135-143.

160

Streszczenie: Moduł sprężystości przy zginaniu statycznym wybranych proweniencji świerka europejskiego (Picea abies [L.] Karst) W pracy zawarto wyniki badań dotyczących wpływu pochodzenia na moduł sprężystości drewna przy zginaniu statycznym. Materiał do badań pobrano z unikatowej powierzchni doświadczalnej Katedry Hodowli Lasu Uniwersytetu Przyrodniczego w Poznaniu. Powierzchnia zlokalizowana jest na terenie Leśnego Zakładu Doświadczalnego Siemianice. Na powierzchni posadzono 20 najlepszych pochodzeń świerka pospolitego w kilku powtórzeniach. Można założyć, że badane populacje świerka wzrastały w bardzo zbliżonych do siebie warunkach środowiskowych. Z dwudziestu pochodzeń rosnących na powierzchni doświadczalnej do badań wybrano siedem: Zwierzyniec Białowieski, Międzygórze, Istebna Bukowiec, Orawa, Zwierzyniec Lubelski, Kartuzy i Nowe Ramuki. Z wytypowanych do badań pochodzeń pobrano materiał w postaci wałków z wysokości pierśnicy. Uzyskane wyniki świadczą o wpływie pochodzenia na moduł sprężystości drewna świerka. Ustalono również które z badanych pochodzeń charakteryzują się najlepszym modułem sprężystości drewna przy zginaniu statycznym.

Corresponding author:

Jarosław Szaban PhD Poznań University of Life Science Departament of Forest Utilization Ul. Wojska Polskiego 71 A 60-625 Poznań Poland e-mail: [email protected]

161 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 162-167 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Investigations the possibility of cellulose determination in wood particles glued with phenol-formaldehyde resin

DOMINIKA SZADKOWSKA, ANDRZEJ RADOMSKI, ANNA LEWANDOWSKA, JAN SZADKOWSKI Department of Wood Science and Wood Protection, Warsaw University of Life Sciences - SGGW

Abstract: Investigations the possibility of cellulose characterising in wood particles glued with phenol- formaldehyde resins. The aim of this study was investigation the suitability of Kürschner-Hoffer method to determine cellulose in wood composites containing phenol-formaldehyde adhesives. On the base of the analysis of model samples of various wood species it was concluded that yield of delignification of glued wood is comparable to non-glued. Size exclusion chromatography was applied for analysis of the isolated celluloses and consistent results of the average molar mass determination were obtained for both glued and non-glued samples.

Keywords: cellulose, wood, Kürschner-Hoffer method, phenol-formaldehyde resin, size exclusion chromatography

INTRODUCTION

Cellulose is one of the most important macromolecular compounds in industry. It is used in primarily in coatings and textiles, but it has more specialised applications, like explosives manufacturing or pharmacy. Cellulose is materials of the future. It can be used in microbiology for special membranes, or extreme engineering. OH OH OH H H H H H H H H H OH H H OH H CH O OH O OH O 3 O O O O O O CH OH O OH O OH 3 H OH H H OH H H OH H H H H H H H H OH n OH

Figure 1. Cellulose molecule Wood is the most important source of cellulose used in industry. Cellulose content in wood is in the range 40 ÷ 60 % (Fengel and Wegener, 2003). It is a structural component, which provides the mechanical strength of wood tissue. There is no absolute method of cellulose determination, due to its linkages with hemicelluloses and lignin. Kürschner-Hoffer method is mild aggressive, leaving below 4 % of residual lignin and showing low degradation of cellulose (Zawadzki et al. 2006, Drożdżek et al. 2008) Phenol-formaldehyde (PF) resins are one of the oldest groups of synthetic polymers. They are used in wood industry for plywood, laminating or sealing chipboard. PF show good mechanical strength and adhesion to wood fibres. Main disadvantages are relatively high cost of them, dark colour associated with phenol oxidation products and elevated temperature necessary for cross-linking process.

162 OH OH

O HOH2C CH2OH + H H

CH2OH OH OH OH H H2 2 CH OH HOH2C C C 2 n OH

CH OH CH2OH CH2OH 2

OH OH OH

Figure 2. Phenol-formaldehyde reactions leading of resin formation

Size-exclusion chromatography (SEC) is a method of macromolecules separation according to their sizes. In the case of well-defined polymers, a relation between size and molar mass may M be expressed in the form of Mark-Houwink equation [η] = KMa, where [η] is intrinsic viscosity, The product [η]M is proportional to molecular size and considered as universal calibration parameter. Application of SEC to cellulose became possible after non- corrosive solvent development by Ekmanis in 1986 (Zawadzki 2009), namely a solution of lithium chloride in N,N-dimethylacetamide (LiCl/DMAc).

MATERIALS AND METHODS

Chips of five species were used: 2 samples of pine (Pinus sylvestris L.), spruce (Picea excelsa L.), poplar (Populus sp. L.), beech (Betula verrucosa Ehrh.) and birch (Fagus sylvatica L.). Model particle boards were made using resol-type phenol-formaldehyde resin at ratios showed in the Table 1.

Table 1. Composition of particle boards used in the study

Species Pine 1 Pine 2 Spruce Poplar Beech Birch

Absolute dry mass of 4.287 4.287 4.287 4.287 4.287 4.287 chips /g

Chips moistrure /% 7.33 8.60 8.78 4.00 8.06 8.71

Dry mass of resin /g 0.386 0.386 0.386 0.386 0.386 0.386

163 The resin was diluted with water (1:1) prior to mixing with air-dry chips in glass vessels. The board were formed by hand-pressing, then cured and dried to constant mass in an oven at the temperature of 120 °C. In order to cellulose isolation, the boards were ground and the samples were taken. The samples containing about 1 g of wood were placed in conical flasks filled with 5 cm3 of nitric acid and 20 cm3 ethanol (Kürschner-Hoffer method) and refluxed for 4 cycles of an hour. Between cycles of heating, the samples were filtered and the fresh mixture HNO3-EtOH was used. Finally, the samples were washed with water, boiled twice for 30 min., filtered, oven-dried at 105 °C and weighed. Reference materials were analysed as well. 15 mg samples of the cellulose obtained were taken and placed in polypropylene pipettes. The samples were swollen in water for 24 h, then filtered and washed with methanol three times within 1-hour pouring-filtering cycles. The same washing procedure was used with N,N-dimethylacetamide (DMAc). Finally, 8 % solution of lithium chloride in DMAc was added to the samples to dissolve cellulose. After 3 days of mixing, the solutions were diluted with pure DMAc to LiCl concentration of 0.5 %. The solutions were analysed by size exclusion chromatography (SEC), using Shimadzu LC-20AD apparatus with refractive index detector. PSS-GRAM 10000 column combined with pre-column were used for analysis at 80 °C, using 0.5 % LiCl/DMAc as eluent at flow of 1.5 to 2.0 cm3/min. Narrow polystyrene standards from PSS were used to universal calibration, using Mark-Houwink equation with the following parameters: –3 3 KPS = 17,35×10 cm /g, αPS = 0,642 – for polystyrene (Timpa 1991) –3 3 Kcel. = 4,58×10 cm /g, αcel. = 0,957 – for cellulose (Krutul 2010)

RESULTS AND DISCUSSION The average results of cellulose determination are presented in the Figure 3, along with standard deviations. In the case of pine 1 and spruce, the results show excellent consistence with reference material. Poplar gave a bit higher, while pine 2 and beech much higher results for glued wood. Non-complete removal of resin or lignin (also resulting from resin presence) is the most probable reason of the over-yield. Quite different observations were made in the case of birch wood, where glued wood gave lower result than reference one. It is possible, that birch wood, known for low durability, are slightly degraded at the conditions applied. This hypothesis may be verified by SEC measurements.

reference PF-glued

40 cellulose content /% cellulose content 20

0 pine 1 pine 2 spruce poplar beech birch

Figure 3. Kürschner-Hoffer cellulose content in glued and reference wood

164 Sample chromatograms of a mixture of polystyrene standards (left) and a cellulose sample were showed in the Figure 4. Molar mass distribution was determined from each cellulose chromatogram, on the base of calibration curve for polystyrene, re-calculated to cellulose using Mark-Houwink dependence.

Figure 4. Chromatogram of a mixture of polystyrene standards (up) and a cellulose sample (down)

The results obtained are showed in the Figure 5 as weight-average molar masses of cellulose samples. In the case of both samples of pine and birch full compatibility was found, as the differences were smaller than standard deviations. For spruce samples, noticeable difference was found, comparable to the standard deviation. The only species, that showed higher molar mass in the case of reference samples, were poplar and beech, while in the case of beech the difference is significant.

165 ) reference PF-glued –1

1000

500 weight-average molar mass of cellulose /(kg·mol

0 pine 1 pine 2 spruce poplar beech birch

Figure 5. Weight-average molar mass of cellulose isolated from glued and reference wood

These results are not completely consistent with cellulose determination results. In the case of birch may be assumed, that partial degradation occurs, leading to ethanol-soluble products, while the rest of cellulose remains unaffected. The results show some similarity in the case of poplar and beech. Both samples gave higher cellulose content and cellulose degradation. Prolonged delignification is needed to complete removal of resin, independently of cellulose depolymerisation. Maybe degradation of wood components leads to stronger interaction with PF resin.

CONCLUSION

Kürschner-Hoffer method of cellulose determination is applicable to wood particles glued with phenol-formaldehyde resins. Due to resin present in material, extended treatment may be necessary, up to four cycles of delignification. The phenomenon is not dependent on wood species division, i.e. gymnosperms or angiosperms. Cellulose isolated from particleboards glued with phenol-formaldehyde resins has almost non-changed molar mass, as compared to cellulose isolated from reference material. Size-exclusion chromatography is easy and suitable method of analysis in this case.

REFERENCES

1. Bikova, T., Treimanis, A. (2002), Problems of the MMD analysis of cellulose by SEC using DMA/LiCl: A review. Carbohydrate Polymers, 48, str. 23-28 2. Drożdżek M., Radomski A.,Zawadzki J., Antczak A. (2008), Changes of molar mass of pinewood (Pinus sylvestris L.) cellulose prepared by Kürschner-Hoffer method, Ann. of Warsaw Agricult. Univ. For. and Wood Technol. 65, 9-13 3. Fengel, D., Wegener, G. (2003). Structure and Ultrastructure, In: Wood Chemistry Ultrastructure Reactions, Walter de Gruyter, Berlin, Germany 4. Krutul D. (2010), „Podstawy badań chromatograficznych celulozy drzewnej” Sprawozdanie z projektu badawczego MNiSW Nr N 309 009 32/1274

166 5. Mansouri H.R., Pizzi A., Leban J-M., (2006), Improved water resistance of UF adhesives for plywood by small pMDI additions, Holz als Roh- Und Werkstoff, 64, str. 218-220 6. Sjöholm, E., Gustafsson, K., Eriksson, B., Brown, W., Colmsjö, A. (2000b), Aggregation of cellulose in lithium chloride/N,N-dimethylacetamide. Carbohyd. Polym., 41, 153-161 7. Zawadzki J. (2009), Wpływ wybranych czynników fizycznych na stopień degradacji celulozy wyodrębnionej z drewna sosny zwyczajnej (Pinus sylvestris L.). Rozprawy Naukowe i Monografie, SGGW, Warszawa 8. Zawadzki J., Radomski A., Antczak A., Drożdżek M. (2006), The Influence of Cellulose Determination Methods on Viscometric Degree of Polymerisation, Ann. of Warsaw Agricult. Univ. For. and Wood Technol. 59, 405-409

Streszczenie: Badanie możliwości charakteryzowania celulozy w wiórach drzewnych zaklejanych żywicami fenolowo- formaldehydowymi. Celem pracy było zbadanie przydatności metody Kürschnera-Hoffera oznaczania celulozy w drewnie do analizy tworzyw drzewnych zawierających żywice fenolowo-formaldehydowe. Na podstawie analizy modelowych próbek z drewna różnych gatunków stwierdzono, że delignifikacja drewna zaklejonego nie zachodzi trudniej niż niezaklejonego. Zastosowano chromatografię wykluczania przestrzennego do analizy wydzielonych celuloz i otrzymano zgodne wyniki oznaczenia średnich mas cząsteczkowych, zarówno dla próbek zaklejonych, jak niezaklejonych.

Corresponding authors:

Dominika Szadkowska, Andrzej Radomski, Anna Lewandowska, Jan Szadkowski Departament of Wood Science and Wood Protaction,

Warsaw Uniwersity of Life Sciences- SGGW, ul. Nowoursynowska 159 02-117 Warsaw, Poland e-mail: [email protected] e-mail: [email protected] e-mail: [email protected] e-mail: [email protected]

167 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 168-175 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Selected aesthetic properties of traditional finish coatings used in furniture making

MICHAŁ SZCZUKA, ANNA ROZANSKA1, WOJCIECH KORYCINSKI2 1 Department of Technology and Entrepreneurship in Wood Industry, Faculty of Wood Technology, Warsaw University of Life Sciences WULS-SGGW, Poland 2 Department of Industrial and Medicinal Plants, University of Life Sciences in Lublin, Poland

Abstract: Selected Aesthetic Properties of Traditional Finish Coatings Used in Furniture Making. Furniture surfaces were covered with finishing materials, most of all for decorative purposes (aesthetics), although other purposes were also important, such as the protection of wood against moisture (durability) and dirt, as well as providing a smooth surface (usage-related function). In order to achieve it, such substances as oils, waxes and French polish have been used for ages, and nowadays also lacquers. The article presents the analysis of colour, gloss and chosen roughness parameters of oak, elm, ash and pine samples, covered with traditional finish coatings used in furniture making. On the basis of tests and the analysis of their results, we can confirm that the use of lacquer, shellac and wax changes the aesthetic properties of wood.

Keywords: wood colour, gloss, roughness, paste wax, shellac, acrylic lacquer

INTRODUCTION The main purpose of furniture making is to improve people's life comfort. Apart from being practical and functional, furniture also served and still serves presentability purposes. The decorative technique, the material used (wood species) and the processing method define the social status of the furniture owner. In the history of furniture making, high status, presentable furniture was richly ornamented, often with the use of very expensive materials. Furniture surfaces were covered with finishing materials, most of all for decorative purposes, although other purposes were also important, such as the protection of wood against moisture and dirt, as well as providing a smooth surface. In order to achieve it, such substances as oils, waxes and French polish have been used for ages, and nowadays also lacquers. The choice of the finishing method defines the aesthetic, resistance and functional features of the surface. Wood surface properties include both aesthetic and resistance properties, and tests of wood surface quality include: visual evaluation and tests of roughness, hardness, resistance to abrasion, resistance to scratches, density profile, wettability and surface tension [Krzysik 1978].

AIM AND SCOPE OF RESEARCH The research aims at evaluating the changes in aesthetic properties of the surface of several different wood species, caused by the application of traditional or contemporary finishing methods; and the comparison of surfaces finished with wax, shellac and lacquer coatings. The scope of work includes colour tests with the Lab system, tests of gloss and selected roughness parameters. The tests were carried out on samples of wood species with diverse properties that were most frequently used in historical furniture making in Poland: oak (Quercus robur L.), elm (Ulmus L.), ash (Fraxinus L.) and pine (Pinus sylvestris L.). We compared results for samples without finish and the same samples after applying different kinds of coatings.

168 MATERIALS AND METHODS Sample preparation. We tested 21 samples of each wood species (100 x 100 mm) polished with sand paper (grit 100 and 150). Before the tests samples were acclimatised in the temperature of 20-23°C and relative air humidity of 50-60%. Samples were tested without finish coatings, and later divided randomly into 3 groups. Each of the three groups received a traditional finish coating: 12% shellac in 99% colourless spirit, paste wax or acrylic lacquer. Technological process of shellac, wax and lacquer application onto sample surface. The shellac used in this research is a 12% solution in the colour called "lemon" (the brightest colour traditionally used for solid wood and veneer-covered furniture) [http:///starwax.pl/produkty/pielegnacja-drewna/ochrona/szelak–indyjski–lemon-0018.html]. It is an Indian shellac with 5% of wax. The samples were covered with three layers of this finish, with a one-hour interval before applying the next layer. The base layer contained 11-14% of shellac, the main shellac layer in the middle contained 8-10% of shellac, and the last, external one from 0-8%. The substance was applied with a soft brush. The wax used to coat the samples was "Wosk Antiquaire", paste 43087 to 43093, produced by the Starwax company [http://www.starwax.pl/produkt/wosk-antiquaire/] - it is a mix of natural (20% beeswax) and synthetic waxes dissolved in petroleum solvent. Samples were covered with a double layer of paste wax. The time interval between applying the first and the second layer was 48 hours. Wax was applied with the help of a soft cloth and polished. Acrylic lacquer of the Vidaron company is a mix based on acrylic resin and additives. It also contains tannin inhibitors that protect wood against stains caused by resins and tannins present in wood [http://www.vidaron.pl/produkty/lakier-akrylowy]. Colour tests. Colour tests were carried out in accordance with the PN-EN ISO 7724- 1:2003 standard, with a spherical spectrophotometer X-Rite SP64. Colour was measured in four corners of each sample. The total colour differences were specified in accordance with the ISO 12647.2. standard. Gloss tests. Gloss was measured in accordance with the PN-EN ISO 2813:2014-11 standard, with the use of the BYK Gardner Micro-TRI-GLOSS gloss meter produced by BYK GmbH, at the angle of 60°, two measurements in parallel and perpendicular to grain. Roughness tests. The chosen roughness parameter was assessed in accordance with the PN-84/D-01005 standard, with a profilometer system using a contact method, with the use of the Mitutoyo roughness tester model SJ-201P. We made two measurements on each sample - in parallel and in perpendicular to grain. The measurement was done on a 12.5 mm long section. In the calculations, we took into account only the Ra parameter, because it is the one that is the most frequently used in Poland, in order to specify the surface roughness of materials, especially in case of finish coatings.

TEST RESULT ANALYSIS Colour tests. Colour brightness differences of individual samples have been presented in the chart below (Fig. 1). Colour brightness practically does not change after the wood is covered with wax or lacquer. In turn, samples covered with shellac have a much darker colour. The difference in brightness L between samples covered with shellac in comparison with samples of the same wood species without coating expressed in [%] can reach up to 16%, due to the colour of the shellac used (Table 1).

169 Table 1. Percentage difference in colour brightness between samples with and without finish. L [%] ash oak elm pine shellac 88 84 84 85 lacquer 99 95 102 100 wax 101 97 96 102

The biggest difference in brightness was measured for the samples of pine covered with wax, and the smallest for shellac-coated oak.

Figure 1. Sample colour brightness in the scale from 0 to 100

On the basis of the standard deviation we can conclude that statistically significant differences in the L parameter between samples of wood with and without coating happen in case of every tested wood species covered with shellac and also in case of oak samples covered with lacquer and wax, and elm samples covered with wax. The differences in sample brightness for samples covered with wax and lacquer are not statistically significant except for elm wood.

Figure 2. Share of green or red component in tested samples, scale from 0 to 100

170 The share of the red colour (parameter "a" of the colour) grows significantly after the samples are covered with the "lemon" colour shellac - in case of ash, this component increased by up to 150% in comparison with wood without coating (Table 2). The second finish that caused the biggest increase was wax on oak and elm (the red component of their colour increased by 17% in comparison with the colour of samples without finish). On the basis of the standard deviation we can conclude that statistically significant differences in the change of the red component between samples before and after coating are observed only for the samples covered with shellac.

Table 2. Percentage differences observed in the tests of the "a" component between samples with and without finish a [%] ash oak elm pine shellac 250 102 197 203 lacquer 102 93 85 76 wax 101 117 117 80

Figure 3. Yellow or blue component amount in the colour of the tested samples, scale from 0 to 150

In case of samples covered with shellac, we also observed an increase of the yellow component. The biggest increase can be observed in case of pine (by 140% in comparison with wood without finish - Table 3). The increase of the yellow component is not that significant for samples covered with lacquer or wax. The only exception being pine wood covered with lacquer and wax, where the increase of the yellow colour component amounted to about 45% in comparison with wood without coating.

Table 3. Percentage differences observed in the test of the "b" component between samples with and without finish b [%] ash oak elm pine shellac 203 156 184 240 lacquer 118 109 111 146 wax 108 116 118 143

The differences between samples covered with lacquer and wax (assessed on the basis of of standard deviation) are not statistically significant, although we can observe small but sometimes statistically significant differences between samples without finish and samples covered with lacquer or wax in case of ash, oak and elm wood. Only in case of samples covered with shellac the differences (in comparison with samples without finish) are clearly bigger than in other cases

171 and they are always statistically significant, similarly to pine before finishing and pine covered with wax and lacquer. On the basis of calculations of colour's ΔE, we observe that a clear and evident total difference in colour (ΔE value over 7) happens for all samples covered with shellac and for pine samples covered with lacquer and wax. A visible colour difference (between 3-7) happens for ash and oak samples covered with lacquer, and oak and elm samples covered with wax. An unperceivable difference in colour (ΔE below 3) happens only in case of elm covered with lacquer and ash covered with wax. Table no. 4 presents the numerical value of total colour difference. Table 4. ΔE value ΔE ash oak elm pine shellac 24,26 16,9 19,84 29,63 lacquer 3,77 3,95 2,59 8,7 wax 1,88 4,25 4,45 8,35

Gloss tests. On the basis of test results presented in Figure 4 for all the wood species, we can observe that in general the biggest gloss is achieved for wood finished with lacquer, and secondly with shellac.

Figure 4. Gloss values for the tested samples

The largest increase in gloss after applying lacquer to the surface was observed for elm samples (by 316% comparing with samples without finish - Table 5). The second method of surface finishing that resulted in the biggest gloss increase was shellac (French polish). The biggest increase in gloss after applying shellac was also observed for elm samples (by 202% comparing with samples without finish). On the other hand, oak samples covered with shellac increase their gloss only slightly; by 123%. In case of the wax finish, the largest increase in gloss was observed for ash wood samples.

Table 5. Percentage differences in gloss test results at a 60° light angle, between samples with and without finish [%] ash oak elm pine shellac 276 223 302 243 lacquer 282 371 416 339 wax 177 127 139 139

Statistically significant differences, assessed on the basis of standard deviation, are observed for ash samples with every kind of finish in comparison with uncoated ash samples. Oak, elm and pine covered with wax are not statistically different from samples without finish and samples covered with lacquer and shellac.

172 Tests of the Ra roughness parameter. On the basis of Figure 5, presenting the test results for the Ra roughness parameter, it can be seen that wax changed sample surface roughness to the largest extent. Moreover, it can be observed that Ra values for lacquer and shellac are comparable, except for oak wood: in this case the Ra value does not change much after the uncoated sample is finished with shellac. The standard deviation shows that the differences between different kinds of finish are not statistically significant. Only in case of deciduous wood species, whose vessels have a diversified anatomical structure (oak, ash, elm), the differences between wood before and after coating are clear and can be statistically significant.

Figure 5. Test results for the Ra roughness parameter

Out of the three kinds of surface finish, the worst Ra results are observed for shellac. After oak samples were coated with shellac, their roughness was reduced only by 11% in comparison with uncoated samples (Table 6); in case of elm it was reduced by 30%, and ash - 33%. In turn, the roughness of pine samples rose by 35%. In case of ash, oak and elm wood covered with lacquer, their roughness decreased by 37%, 45%, and 37% respectively; while in case of pine once more we observed an increase (by 28%) comparing with wood without finish. In case of pine, shellac and acrylic lacquer finish increases its surface roughness: by 35% for shellac and 28% in case of lacquer. Wax applied to oak and elm samples caused a decrease in roughness by 45% on average. Table no 6 presents the percentage differences in roughness test results between samples with and without finish.

Table 6. Percentage differences in Ra value between samples with and without finish [%] ash oak elm pine shellac 67 89 70 135 lacquer 63 55 63 128 wax 69 56 54 84

On the basis of standard deviation we can conclude that statistically significant differences happen in case of ash before and after applying shellac and lacquer, as well as uncoated elm samples and elm samples with all 3 kinds of finish. In case of oak wood without finish, significant differences are observed only for lacquer and wax. There are no statistically significant Ra differences in case of pine samples before and after coating.

Test result analysis. The results of earlier studies carried out at our Faculty (Wood Technology at SGGW - Warsaw University of Life Sciences), show that the brightness and

173 saturation of sample colour does not change significantly after the surface is covered with wax, only the wood pattern becomes more distinct, which increases the aesthetic value of the surface. On the other hand, we observe an increase of surface gloss [Rozanska et al. 2012]. The presented tests indicate that lacquer and shellac cause a large increase of gloss when applied to wood samples, while wax caused a significant gloss increase only in case of ash samples. The difference in the assessment of the degree of gloss increase can result from the context (in previous studies wax was compared with varnish and in this article it is compared with shellac and lacquer) and a different kind of wax applied (100% natural beeswax vs. a paste wax containing 20% of beeswax). The colour of samples covered with wax and acrylic lacquer did not change. According to another research [Magoss 2008; Rousek et al. 2013], the most significant reduction of wood surface roughness is achieved after covering it with wax. The tests conducted during our study also indicate that wax is the most efficient kind of finish when it comes to reducing the Ra surface roughness parameter of wood. This is because wax penetrates into the porous structure of wood, filling the vessels and the cell lumens uncovered during wood processing [Magoss, Sitkei 2001]. According to the researchers, wood surface irregularities and their degree are due to the local positions of pores in the wood structure, the diameter of tracheids and lumens of cells cut through during wood processing, as well as the layout of vessels in parallel to the cutting direction. The test results presented in this article show that among the deciduous wood species under research, the biggest decrease in the Ra roughness parameter (even up to 50%) is observed for oak samples covered with wax and lacquer - that is, for the wood species, whose structure is the most diversified and has large vessels; while the smallest decrease happened in case of pine.

CONCLUSIONS 1. The application of finish to wood changes the aesthetic properties of its surface. 2. The largest total colour difference is observed for pine - the brightest wood species. Wax and lacquer cause the smallest total changes in colour. The "lemon" colour shellac causes a significant total colour difference. Colourless wax and laquer coatings applied to wood do not significantly change its brightness. The biggest increase in the red and yellow components of wood colour can be achieved after the surface is covered with shellac in its "lemon" colour variant. The application of lacquer and wax practically does not change the "a" and "b" parameters, except for yellowish wood - pine - in which case the "b" parameter is changed also by lacquer and wax. 3. Gloss tests show that the biggest increase in wood gloss happens after its surface is covered with acrylic lacquer or shellac. 4. Wood roughness depends on its anatomical structure rather than on the kind of finish. Out of all the kinds of finish, wax and lacquer are more efficient in reducing roughness (Ra parameter) than shellac. Wax and lacquer cause the biggest change in the Ra roughness parameter in case of oak, due to its highly varied anatomical structure.

REFERENCES 1. KRZYSIK F., 1978: Nauka o drewnie, Państwowe Wydawnictwo Naukowe, Warszawa. 2. MAGOSS E., 2008; General regularities of wood surface roughness, Acta Silv. Lign. Hung. 4:81-93. 3. MAGOSS E., SITKEI G., 2001; Fundamental Relationships of the Wood Surface Roughness at Milling Operations. Proc. of the 15th IWMS Conf. Los Angeles. 437-446. 4. ROZANSKA A., KORYCINSKI W., AURIGA R., BEER P. 2012: Characteristics of the properties of traditional finishing coatings used to protect wood in antique parquets considering the possibility of their application in buildings under reconstruction, Annals of Warsaw University of Life Sciences Forestry and Wood Technology No 80: 22-27.

174 5. ROUSEK et all. , 2013: Experimental study of milling wood surface properties (roughness), Annals of Warsaw University of Life Sciences Forestry and Wood Technology No 81: 217-222. 6. http:///starwax.pl/produkty/pielegnacja-drewna/ochrona/szelak-indyjski-lemon-0018.html 7. [http://www.starwax.pl/produkt/wosk-antiquaire/] 8. http://www.vidaron.pl/produkty/lakier-akrylowy]

Streszczenie: Wybrane właściwości estetyczne tradycyjnych powłok wykończeniowych stosowanych w meblarstwie. Powierzchnie mebli pokrywane były materiałami wykończeniowymi przede wszystkich w celach dekoracyjnych (estetyka), choć nie bez znaczenia pozostawało także zabezpieczenie drewna przed negatywnym wpływem wilgoci (trwałość), zabrudzeniem oraz nadanie gładkości (funkcja użytkowa). Dla tych celów od wieków stosowane były oleje, woski, politury, a współcześnie lakiery. W artykule przedstawiono analizę barwy, połysku oraz wybranych parametrów chropowatości próbek dębu, wiązu, jesionu i sosny, pokrytych tradycyjnymi powłokami wykończeniowymi stosowanymi w meblarstwie. Na podstawie wykonanych badań i analizy ich wyników można stwierdzić że pokrycie lakierem, politurą oraz woskiem zmienia właściwości estetyczne drewna.

Słowa kluczowe: barwa drewna, połysk, chropowatość, pasta woskowa, politura, lakier akrylowy

Corresponding author:

Anna Rozanska Department of Technology and Entrepreneurship in Wood Industry Faculty of Wood Technology, Warsaw University of Life Sciences – SGGW, Ul. Nowoursynowska 159, 02-776 Warsaw, Poland e-mail: [email protected]

175 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 176-180 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Enzymatic hydrolysis of different cellulose materials

KINGA SZENTNER, AGNIESZKA WAŚKIEWICZ, ELŻBIETA LEWANDOWSKA, PIOTR GOLIŃSKI

Department of Chemistry, Poznań University of Life Sciences, 60-625 Poznan, Poland

Abstract: Enzymatic hydrolysis of different cellulose materials Susceptibility of various cellulosic materials (Whatman No. 1, Avicel - PH 101) to their enzymatic degradation was tested. Hydrolysis was run using cellulase obtained from Trichoderma ressei. HPLC analysis showed that Whatman No. 1 was more susceptible to bioconversion of cellulose. This is partly explained by its more amorphous structure in comparison to microcrystalline Avicel cellulose. Conducted FTIR analysis focusing on changes within band vibrations in amorphous and crystalline systems as well as the glycoside bond confirmed that due to the used material the enzymes influence structural changes of cellulose. Presented results of both HPLC and FTIR confirmed that effectiveness of enzymatic hydrolysis of cellulose is connected with the structure and properties of a given cellulose material.

Keywords: cellulose, enzymatic hydrolysis, cellulase, HPLC, FTIR

INTRODUCTION

Cellulose is the most abundant polysaccharide on Earth, [Cialacu et al. 2011] consisting of D- anhydroglucopiranose units bound by β-1,4-glycosidic bonds. The repeating unit of this polymer is cellobiose. Cellulose materials comprise crystalline and amorphous domains, which shares vary depending on the source and method, in which the material is obtained [Ciolacu at al. 2011]. Thanks to the chemical properties of cellulose it has found numerous and diverse applications, both in science and technology. Several studies have focused mainly on the improvement of cellulose hydrolysis, particularly using cellulolytic enzymes. Enzymatic degradation of cellulose is considered to be the hydrolysis method with the greatest potential for improvement of ethanol production, while it is also of great importance in polymer chemistry. Availability of cellulose materials and their susceptibility to enzymatic degradation depend on many factors, e.g. structure, porosity, the degree of polymerisation and crystallinity (the share of crystalline and amorphous areas) [Mansfield at al. 1999, Mansfield et al. 2003, Wiman et al. 2012, Cao and Tan 2002], surface area and insoluble nature [Ciolacu at al. 2011, Zhang and Lynd 2004, Yea et al. 2010]. Another important criterion determining the process of hydrolysis is connected with absorbability of cellulase. A considerable role is played by the initial substrate and an adequate level of enzymes. Cellulose hydrolysis requires a synergistic action of three different types of cellulases: cellobiohydrolase (CBH, EC 3.2.1.91), endoglucanase (EG, EC 3.2.1.4) and β-glucosidase (EC 3.2.1.21) [Mansfield at al. 2003, Gan et al. 2003]. EG enzymes digest randomly cellulose strands to reduce the degree of polymerization of the cellulose chain into smaller subunits (preferably in cellulose amorphous regions). CBH enzymes act on the existing chain ends (or generated by endoglucanase) and release cellobiose. These enzymes digest both amorphous and crystalline cellulose, but it is the only one for the efficient degradation of crystalline cellulose. The presence of β-glucosidases, promoting hydrolysis of cellobiose to glucose. An adequate level of this enzyme limits inhibition of hydrolysis [Kumar et al. 2008]. The aim of this study was to examine the effect of various cellulose materials on their enzymatic hydrolysis. Susceptibility of selected cellulose materials to their enzymatic

176 degradation was analyzed using HPLC by determining the concentration of cellobiose and glucose. In turn, structural changes in the cellulose material under the influence of enzymes were assessed using Fourier transform infrared spectroscopy (FTIR).

MATERIALS AND METHODS

Chemicals The cellulosic substrates were: Avicel PH-101 (Fluka) and Whatman No. 1 (Sigma–Aldrich). Cellulase obtained from Trichoderma ressei ATCC 26921 (Sigma–Aldrich).

Enzymatic treatment (hydrolysis) of cellulose Reactions were run in vials with 100 mg of cellulose in 1.0 ml citrate buffer 50 mM pH 4.9, plus 0.5 ml of cellulase, which was dilluted (1:50) in buffer. Reaction mixtures were incubated at 500C for 1.5; 2.5; 4.0, 8; 12, 14, 48 and 72 hours. The rotation speed was 150 rpm. The hydrolysis reaction was stopped by boiling the hydrolysis residue for 5 min. The samples were stored at -200C until HPLC analysis.

HPLC analysis Samples after enzymatic hydrolysis were centrifuged at 13,000 rpm for 10 min and then filtered through a 0.20 µm filter before injection. Contents of reducing sugars - glucose and cellobiose, were analyzed using the 2695 Waters high performance liquid chromatography (HPLC) system coupled to a 2414 Refractive Index (RI) detector (Waters, Milford, MA, USA), equipped with a Bio-Rad Aminex HPX-87H column (Bio-Rad, USA) at the column temperature of 65°C and the EmpowerTM 1 software for data processing. The mobile phase was 0.5 mM H2SO4 with a flow rate of 0.6 mL/min. Quantification of sugars was performed by measuring the peak areas at the retention time according to the relevant calibration curve.

FTIR analysis The residue of cellulose after the enzymatic reaction was analyzed with the use of FTIR spectroscopy. Cellulose samples were dried overnight first in an oven at 600C and further over P2O5. FTIR spectra were obtained using the KBr (Sigma–Aldrich, Germany) pellet technique (1mg cellulose/200 mg KBr). Spectra were recorded using an Infinity spectrophotometer by Mattson Infinity with Fourier transform in the range from 550 to 4000 cm-1 at a resolution of 2 cm-1 recording 64 scans. Basic spectra were transposed to their second derivative (D2) using the Win First software.

RESULTS

Effects of enzymatic hydrolysis using two different cellulose materials (Whatman and Avicel) were tested by HPLC chromatographic analysis of sugar (glucose and cellobiose) concentrations (Figure 1).

177

Figure 1 Reducing sugars content in different cellulose materials: Whatman No.1 (A) and Avicel (B) after enzymatic reaction

Both in the case of Whatman and Avicel after 24 h a increase was observed in glucose concentration, with the maximum concentration (10.54 mg/ml – Avicel and 20.61 mg/ml – Whatman) at 72 h. Cellobiose concentration remained relatively stable throughout the entire process of hydrolysis, showing no significant fluctuations (0.09-0.19 mg/ml – Avicel and 1.44-0.95 mg/ml - Whatman). The recorded sugar levels confirm that Whatman No. 1 is more susceptible to hydrolysis in comparison to Avicel cellulose. This is connected both with the different porosity and lower crystallinity of that material in comparison to Avicel cellulose. Analyses indicate that initial crystallinity of a cellulose material is a very important, but not sufficient parameter determining susceptibility of cellulose material to enzymatic degradation. Figures 2 and 3 present spectra of Avicel cellulose and Whatman No.1 subjected to enzymatic hydrolysis at selected time intervals (1.5; 24; 48 and 72 h). When evaluating structural changes in analyzed cellulose materials bands 1430, 1370, 1160 and 895 were considered.

Figure 2. Spectra of the second derivative of Avicel cellulose: initial material(A), after 1.5-h (B), after 24-h (C), after 48-h (D), after 72-h (E) enzymatic treatment

178 It may be concluded from the presented spectra that both Whatman No. 1 and Avicel cellulose are susceptible to enzymatic hydrolysis. Spectra of the second derivative (D2) in Figs. 2 and 3 indicate changes in band intensity in the -1 area of 1430 cm responsible for symmetric deforming vibration CH2 at C6. This band is associated with the crystalline structure of cellulosic materials. The decrease in the intensity of the band at 895 cm-1 indicate considerable susceptibility of amorphous regions. They are ascribed to stretching vibrations of the COC β-1,4- glycoside bond, stretching vibrations of COC, CCO, CCH at C5 and C6. Significant changes were observed also for vibrations at 1370 cm-1 deforming CH as well as the glycoside bond (asymmetric bridge C-O-C stretching) at 1158 cm-1 in all tested materials. Interpretation of IR spectra was based on studies (Oh et al. 2005).

Figure 3. Spectra of the second derivative of Whatman No.1 cellulose: initial material(A), after 1.5-h (B), after 24-h (C), after 48-h (D), after 72-h (E) enzymatic treatment

FTIR analysis for cellulose materials shows that enzymes influence changes in crystalline and amorphous areas of cellulose. Presented results of both HPLC and FTIR confirmed that effectiveness of enzymatic hydrolysis of cellulose is connected with the structure and properties of a given cellulose material.

REFERENCES

1. CAO YU, TAN H., 2002: Effects of cellulase on the modification of cellulose, Carbohydrate Research 337; 1291-1296 2. CAO YU, TAN H., 2005: Study on crystal structures of enzyme-hydrolyzed cellulosic materials by X-ray diffraction, Enzyme and Microbial Technology 36; 314-317

179 3. CIOLACU D., GORGIEVA S., TAMPU D., KOKOL V., 2011: Enzymatic hydrolysis of different allomorphic forms of microcrystalline cellulose, Cellulose 18; 1527-1541 4. CIOLACU D., CIOLACU F., POPA V.I., 2011: Amorphous cellulose – structure and characterization, Cellulose Chemistry and Technology 45; 1-2, 13-21 5. GAN Q., ALLEN S.J., TAYLOR G., 2003: Kinetic dynamics in heterogeneous enzymatic hydrolysis of cellulose: an overview, an experimental study and mathematical modeling, Process Biochemistry 38; 1003-1018 6. KUMAR R., SINGH S., SINGH OV. 2008: Bioconversion of lignocellulosic biomass: biochemical and molecular perspectives, J Ind. Microbiol. Biotechnol. 35; 377 – 391 7. MANSFIELD S.D., MEDER R., 2003: Cellulose hydrolysis – the role of monocomponent cellulases in crystalline cellulose degradation, Cellulose 10; 159- 169 8. MANSFIELD S.D., MOONEY C., SADDLER J.N., 1999: Substrate and Enzyme Characteristics that Limit Cellulose Hydrolysis, Biotechnol. Prog, 15; 804-816 9. OH S.Y., YOO D.I., SHIN Y., KIM H.CH., KIM H.Y., CHUNG Y.S., PARK W.H., YOUK J.H., (2005): Crystalline structure analysis of cellulose treated with sodium hydroxide and carbon dioxide by means of X-ray diffraction and FTIR spectroscopy, Carbohydrate Res., 340: 2376-2391 10. WIMAN M., DIENES D., HANSEN M.A.T., MEULEN T., ZACCHI G., LIDEN G., 2012: Cellulose accessibility determines the rate of enzymatic hydrolysis of steam- pretreated spruce, Bioresource Technology 126; 208-215 11. YEA AI, HUANG YC, CHEN SH., 2010: Effect of particle size on the rate of enzymatic hydrolysis of cellulose, Carbohyd. Polym. 79; 192-199 12. ZHANG Y.P., LYND L.R., 2004: Toward an aggregated understanding of enzymatic hydrolysis of cellulose: Nanocomplex cellulase systems, Biotechnol. Bioeng., 88; 798 – 824

Streszczenie: Enzymatyczna hydroliza różnych materiałów celulozowych. Przebadano podatność zróżnicowanych materiałów celulozowych (Whatman nr 1, Avicel - PH 101) na ich enzymatyczny rozkład. Proces hydrolizy prowadzony był przy użyciu celulazy otrzymanej z Trichoderma ressei. Analiza HPLC wykazała, że najbardziej podatnym materiałem na biokonwersję celulozy okazała się bibuła Whatmana. Częściowo tłumaczy to jej bardziej amorficzna struktura w porównaniu z mikrokrystaliczną celulozą Avicel. Analiza FTIR ze szczególnym uwzględnieniem zmian w obrębie drgań pasm układów amorficznych, krystalicznych oraz w obrębie wiązania glikozydowego potwierdziła, że bez względu na wykorzystywany materiał enzymy wpływają na zmiany strukturalne celuloz. Prezentowane wyniki zarówno HPLC oraz FTIR potwierdzają, że efektywność enzymatycznej hydrolizy celulozy jest związana ze strukturą i właściwościami danego materiału celulozowego.

Acknowledgement The study was funded by National Science Centre, Poland, grant No. 2014/13/B/NZ9/02442

Corresponding author:

Kinga Szentner Poznań University of Life Sciences, Department of Chemistry Wojska Polskiego 75 PL 60 - 625 Poznan, Poland e-mail: [email protected]

180 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 181-187 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The effect of tree slenderness on wood properties in Scots pine. Part I: Basic density and compression strength parallel to grain

ARKADIUSZ TOMCZAK, TOMASZ JELONEK, MARCIN JAKUBOWSKI, WITOLD GRZYWIŃSKI, JAROSŁAW SZABAN Poznań University of Life Sciences, Faculty of Forestry, Department of Forest Utilization

Abstract: The effect of tree slenderness on wood properties in Scots pine. Part I: Density and compression strength parallel to grain. The aim of this study was analyse the variability in basic density (Qbd) and compression strength parallel to grain of the wood in pine trunks (Rc). We put forward the hypothesis that the density and strength of the wood will be greater in more slender trunks, and that the variability in the properties in slender trunks will be smaller. The study was carried out in mature pine stands, located in north-western Poland. A selection was made of 14 model trees with similar diameter at breast height and similar length of crown. The mean values of HDR were 74 for the shorter trees (S74), and 87 for the taller trees (S87). The wood density of the trees with lower slenderness ratio (S74) was 421 kg/m3, and that of the trees with the higher ratio (S87) was 439 kg/m3. Also the compression strength parallel to grain for the trees in the S87 group was higher, at 24.2 MPa (compared with 22.6 MPa for the S74 group). Analysis of variance and multiple comparisons showed that there exist statistically significant differences between the means for trees with different slenderness ratio (HDR) and between the means obtained for samples taken from different parts of the trunk (SN). Generally Qbd and Rc exhibited smaller variability in the trunks of trees with higher HDR.

Keywords: tree stability, height-to-diameter ratio, Pinus sylvestris

INTRODUCTION The trunk of a tree is constantly subjected to static loads, due to the weight of the trunk itself and the crown. Wind produces additional dynamic loads. The ability of a tree to maintain static and dynamic equilibrium is called stability. The most common measure of stability is the slenderness ratio (height-to-diameter ratio, or HDR). Trees with higher HDR values are expected to be less stable, and vice versa. The HDR is easily computed, and is therefore used frequently in practice and in scientific research (Orzeł 2007; Kijidani et al. 2010; Bošeľa et al. 2014; Kaźmierczak et al. 2015; Korzeniewicz et al. 2016). In reality, the stability of a tree is not solely dependent on the relationship between DBH and height. Other significant morphological features of a tree include, for example, the relative length and slenderness of the crown (Jelonek 2013). Tomczak et al. (2015) report that, in the heliophilous Scots pine, the dimensions of the crown change along with an increase in height and drop in stability. There is an increase in the absolute and relative length and slenderness of the crown. That is to say, the risk of loss of stability in taller trees is compensated by changes in the crown architecture. In pines, trunk slenderness changes with the age of the tree. Tress in younger stands exhibit low stability. In the course of commercial thinning, selected trees are removed, and those remaining then have more space to grow and do not need to compete for light. In consequence height increments become smaller and thickness increments larger, and there is also a change in the HDR (Wallentin and Nilsson 2013). Aiba and Nakashizuka (2009) conclude that the architecture of all heliophilous species is optimised in terms of height increment, while the architecture of shade-tolerant and sciophilous species is optimised for light capture and mechanical stability. A tree’s biomechanical system is thus a complex network of influences and dependences. It is often explained using the theoretical principles of structural engineering. A basic assumption is that plants cannot violate the laws of physics (Niklas 1992). However, plant material does not behave under mechanical load like steel or

181 concrete, and may not conform exactly to current mechanical models (James et al. 2014). According to Sellier and Fourcaurd (2009) material properties play a limited role in a tree’s dynamics. This is also implied by the results of research comparing the properties of wood from wind-damaged and undamaged trees. The differences obtained are often statistically insignificant (Cameron and Dunham 1999; Meyer et al. 2008; Tomczak et al. 2013; Jakubowski et al. 2014). Tomczak et al. (2011) state that mean values are not indicators of a tree’s resistance to the action of strong winds, and that the biomechanics of a trunk are better described by the axial and radial variation in wood properties. On trunk cross-sections, significantly greater rates of change in wood density were observed in the case of undamaged trees. In undamaged trees the wood density increased rapidly from the pith to the bark. In wind-damaged trees wood density increased slowly. A particularly large difference in wood density was observed on the compressed (leeward) side of the trunk (Tomczak et al. 2011). The goal of the present work is to analyse the variability in basic density and compression strength parallel to grain of the wood in pine trunks. We put forward the hypothesis that the density and strength of the wood will be greater in more slender trunks, and that the variability in the properties in slender trunks will be smaller. Model trees for the experiment were selected on the basis of DBH and height. All trees had similar DBH, and the distinguishing feature for the groups was tree height.

MATERIALS The study was carried out in mature pine stands, located in north-western Poland. A selection was made of 14 model trees with similar diameter at breast height (DBH) and similar length of crown (Cl). The mean height of seven of the trees was 23.7 m, while the mean height of the other seven was 27.6 m (Table 1). The difference was statistically significant (p-value<0.05). The slenderness ratio (HDR) was calculated by dividing the tree height (h) by the DBH value. The mean values of HDR were 74 for the shorter trees (S74), and 87 for the taller trees (S87). The difference was statistically significant (p-value<0.05). Prior to felling of the model trees, the crown diameter (Cd) was measured based on the vertical projection. The following indicators of crown structure were calculated: relative length (RCl) and slenderness (Cs). The relative length of the crown was given by the formula RCl=Cl/h, and the crown slenderness by the formula Cs=Cd/Cl.

Table 1. Description of model trees Slenderness [h:d] S74 (n=7) mean ± SD S87 (n=7) mean ± SD DBH [cm] 32,2 ± 1,0 31,7 ± 0,7 Tree height [m] 23,7 ± 0,7 27,6 ± 1,6 Crown length [m] 8,4 ± 1,9 8,3 ± 1,5 Crown diameter [m] 3,4 ± 1,2 4,0 ± 1,4 Relative crown length 0,36 ± 0,08 0,30 ± 0,06 Crown slenderness 0,42 ± 0,13 0,51 ± 0,27

Next the model trees were felled, and the tree length was measured to an accuracy of 0.1 m. Based on the value obtained it was determined at what distances the tested sections should be spaced. From each trunk we cut a total of five logs (80 cm trunk sections). The first, closest to the butt end of the trunk, corresponded to breast height. Trunks were cut in the following manner. From the point marking breast height: 40 cm upwards and downwards. Sections situated higher were determined using relative values, corresponding to 20%, 40%, 60% and 80% of the length of the trunk. From each tested section, samples were cut out for laboratory tests. The samples were located along two radii running eastwards and westwards (Fig. 1).

182 Figure 1. Schema for the collection of material for analysis of wood properties

Samples with standardised cross-section (20x20 mm) were located adjacent to each other, along the radius, the first at a distance of at least 1 cm from the pith. This eliminates the effect of cambial age on the wood properties, and thus enables information to be obtained on the mean value for the whole of the trunk cross-section. Basic density (Qbd) is the ratio of the dry mass of the wood to its volume at maximum swelling. Samples were weighed after drying to an accuracy of 0.001 g. To obtain results close to the wood properties characteristic of growing tree trunks, the strength of the wood was measured at a moisture higher than 30% (above the saturation point of the fibres). The limiting moisture of the membranes was obtained by immersing the samples in water until they attained dimensional stability, that is, until the increments in the individual dimensions of the samples measured at a time interval of 72 hours were equal to or less than 0.2 mm (PN−77/D−04101). Compression strength parallel to grain (Rc>30%) was determined in accordance with the PN−79/D−04102 standard. For the purpose of comparison of properties, the data were subjected to statistical analysis. Selected morphological features were compared between groups of trees with different slenderness using the t-Student test. Next Levene’s test of homogeneity of variance was performed. Analysis of variance (ANOVA) was used to identify significant differences in the measurements between groups of trees (HSD) and among samples from different parts of the trunk (SN, GO). When differences were found, we performed multiple comparisons using Tukey’s HSD test. Statistical conclusions were reached using a significance level of α=0.05. Calculations were performed using the Statistica 12PL application (StatSoft Inc.).

RESULTS AND DISCUSSION The shorter trees (S74) had crowns which were narrower (3.4 m), relatively longer and more slender (Table 1). With a relatively longer and slender crown the stability of the tree increases, because its centre of mass is lower. On the basis of the morphological properties of the shorter trees and the HDR value, they can be described as stable. The taller trees, according to the scale of values given by Burschel and Huss (1997), are classified as unstable. No statistically significant differences were found between the properties of the crowns (p-value<0.05). This means that the only differentiating factor between the studied groups of tree was their height. The height of the taller group of trees was greater by 3.9 m (difference statistically significant at p<0.05). In this study two properties were compared: basic density and compression strength parallel to grain. Density is a determinant of wood quality, and is a property strongly correlated with the structure of the wood (Saranpää 2003; Klisz et al. 2015). On the other hand, differences in wood density are observed between trees, stands and populations

183 (Swenson and Enquist 2007; Tomczak 2013). It is therefore a property which, like compression strength parallel to grain, one may attempt to correlate with mechanical stability. Such analyses have been carried out by, among others, Onoda et al. (2010). In our study, however, to eliminate the effect that the structure of the wood has on its properties, we selected trees with very similar DBH and different heights. At similar DBH the annual rings have similar width and a similar proportion of late wood. This results from the relationship, characteristic for any given species, between the wood structure and the rate of thickness increment. The variable having an impact on the slenderness ratio, therefore, was the tree height.

Table 2. Results of variance analysis basic density compression strength pararell to grain Source of Sum. D. F- p-value Sum. D. F- p-value variance sq. f. Mean sq. value Sq. f. Mean sq. value HDR 13966 1 13966 5,27 0,022311 322,0 1 322,0 22,72 0,000003 SN 575108 4 143777 54,24 0,000000 1949,3 4 487,3 34,39 0,000000 GO 10223 1 10223 3,86 0,050354 0,0 1 0,0 0,00 0,980031 HDR*SN 14081 4 3520 1,33 0,259107 111,6 4 27,9 1,97 0,098772 HDR*GO 727 1 727 0,27 0,600901 22,9 1 22,9 1,61 0,204654 SN*GO 12267 4 3067 1,16 0,329679 37,7 4 9,4 0,67 0,616546 HDR*SN*GO 1942 4 485 0,18 0,947071 27,9 4 7,0 0,49 0,741057 Error 909167 343 2651 5271,8 372 14,2 Legend: HDR – height diameter ratio; SN – sample number; GO – geographical orientation

Table 3. Mean basic density and compression strength parallel to grain from different parts of trunk basic density [kg/m3] compression strength parallel to grain [MPa]

S74 S87 S74 S87

SN mean n SD VC mean n SD VC mean n SD VC mean n SD VC DBH 474,2 53 63,1 13,32 491,7 54 59,2 12,05 25,6 52 3,8 14,84 26,1 63 4,3 16,48 20% 438,7 46 48,9 11,15 442,4 44 42,2 9,54 24,5 46 4,6 18,78 25,4 50 4,1 16,14 40% 379,2 39 40,6 10,71 403,3 40 33,7 8,37 20,6 40 3,6 17,48 22,7 44 3,2 14,10 60% 364,8 31 37,1 10,16 397,9 26 27,5 6,90 19,5 31 2,4 12,31 21,7 31 2,8 12,90 80% 409,4 16 105,4 25,75 396,9 14 38,2 9,62 18,2 17 2,7 14,84 22,4 18 3,9 17,41 In total 421,4 185 70,63 16,76 438,5 178 58,9 13,43 22,6 186 4,6 20,35 24,2 206 4,2 17,36 Legend: n – number of samples, SD – standard deviation, VC – variability coefficient

Table 4. Differences between parts of trunk basic density compression strength parallel to grain

S74 S87 S74 S87

SN relation absolute relative absolute relative absolute relative absolute relative DBH - 20% -35,5 -7,5 -49,3 -10,0 -1,1 -4,3 -0,7 -2,7 20% - 40% -59,5 -13,6 -39,1 -8,8 -3,9 -15,9 -2,7 -10,6 40% - 60% -14,4 -3,8 -5,4 -1,3 -1,1 -5,3 -1,0 -4,4 60% - 80% 44,5 12,2 -1,0 -0,2 -1,3 -6,7 0,7 3,2 Legend: absolute [kg/m3 or MPa], relative [%]

The wood density of the trees with lower slenderness ratio (S74) was 421 kg/m3, and that of the trees with the higher ratio (S87) was 439 kg/m3. Also the compression strength parallel to grain for the trees in the S87 group was higher, at 24.2 MPa (compared with 22.6 MPa for the S74 group). Analysis of variance and multiple comparisons showed that there exist statistically significant differences between the means for trees with different slenderness

184 ratio (HDR) and between the means obtained for samples taken from different parts of the trunk (SN) (Table 2). We found that the density and compression strength parallel to grain were statistically significantly lower (p-value=0.05) in the trunks with lower slenderness (S74), but only for the means from all samples from the whole of the trunk. Comparison of the properties only at breast-height level, for example, did not produce the expected results: no statistically significant difference were then found. The results of analysis of variance, however, indicate that significant differences do occur. They relate to the variation which we observed in the compared groups of trees. The highest values of the studied properties were found, naturally, in the lower parts of the trunk (at breast height and the point at 20% of the height of the tree). In the case of density, the variation in that property characteristic of pine was observed (Witkowska and Lachowicz 2013; Auty et al. 2014), with a fall in the value followed by an increase in the upper part of the trunk (Table 3). Similar variation was found in the compression strength parallel to the wood grain (Rc) in the trunks group S87. The strength of the wood in the trunks of trees with lower slenderness ratio varies in a different fashion. The value of this property is markedly lower in the top part of the trunk than in the lower part. Generally Qbd and Rc exhibited smaller variability in the trunks of trees with higher HDR (Table 4). Compared with other morphological features, the correlation of tree height with wood properties is weak. Tomczak (2014) showed that tree height correlates chiefly with wood compression strength. However, that analysis concerned juvenile wood, namely the central part of the trunk cross-section. Tomczak and Jelonek (2014) investigated relationships between morphological features of trees and the green density of wood on the perimeter part of the trunk cross-section. The investigated property in different parts of the trunk was found to be related to the tree height. The differentiation in the structure and properties of wood in the trunk is an example of a process leading to a biostructure that is optimum in physiological and mechanical terms. For example, juvenile wood, being lighter and mechanically weaker, occupying the central part of the trunk cross-section, fills in the “pipe” created by the heavier and stronger mature wood. Thanks to this kind of differentiation the stability of the tree – the ability of the trunk to transfer static and dynamic loads – appears to be significantly greater than it would be in the case of a structure with homogeneous structure and properties. Analysis of the data from the whole of the cross-section (including both young and mature wood) leads to similar conclusions, primarily in relation to compression strength parallel to grain.

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LIST OF STANDARDS 1. PN−77/D−04101. Drewno. Oznaczanie gęstości. 2. PN−79/D−04102.Drewno. Oznaczanie wytrzymałości na ściskanie wzdłuż włókien.

Streszczenie: Właściwości drewna sosen zróżnicowanych pod względem smukłości pnia. Część I: gęstość i wytrzymałość na ściskanie wzdłuż włókien. Celem pracy była analiza zmienności gęstości umownej i wytrzymałości drewna na ściskanie wzdłuż włókien w pniach sosen, przy założeniu że badane właściwości będą miały tym wyższe wartości im wyższy będzie współczynnik smukłości. Badania wykonano w dojrzałych drzewostanach sosnowych, z północno zachodniej części Polski. Wybrano 14 drzew modelowych o zbliżonej pierśnicy i zbliżonej długości korony. Średnia wysokość 7 drzew wynosiła 23,7 m, kolejnych 7 – 27,6 m. Średnia wartość współczynnika smukłości dla drzew niższych wynosiła 74 (S74), a dla drzew wyższych 87 (S87). Drzewa niższe charakteryzowały się koronami węższymi (3,4 m), względnie dłuższymi i bardziej smukłymi. Przy względnie dłuższej i smukłej koronie stabilność drzewa wzrasta, ponieważ środek ciężkości położony jest niżej. Biorąc pod uwagę cechy morfologiczne drzew niższych oraz wartość h:d można określić je jako stabilne. Natomiast drzewa wyższe według skali wartości podanej przez Burschela i Hussa (1997) należy ocenić jako niestabilne. Gęstość drewna drzew o niższym współczynniku smukłości (S74) wynosiła 421 kg/m3, u drzew o wyższym współczynniku (S87) 439 kg/m3. Również wytrzymałość drewna na ściskanie wzdłuż włókien była wyższa u drzew z grupy S87 i wynosiła 24,2 MPa (S74= 22,6 MPa). Analiza wariancji i porównania wielokrotne wykazały, że istnieją statystycznie istotne różnice pomiędzy średnimi dla drzew o różnym współczynniku smukłości oraz pomiędzy średnimi uzyskanymi dla prób pobranych z różnych części pnia. Na przekroju podłużnym pnia wartości badanych właściwości malały w kierunku od podstawy do wierzchołka i jest to cecha dla sosny charakterystyczna. Przy czym wyższe współczynniki zmienności oraz większe różnice pomiędzy punktami pomiarowymi, rozłożonymi wzdłuż strzały, zaobserwowano w przypadku drzew niższych, stabilniejszych. Drzewa, które określa się jako stabilne, charakteryzują się więc drewnem o niższej jakości technicznej i mniejszej jednorodności.

Corresponding author:

Arkadiusz Tomczak Poznań University of Life Sciences, Faculty of Forestry, Department of Forest Utilisation Wojska Polskiego 71A, 60 – 625 Poznań E-mail: [email protected]

187 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 188-194 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The effect of tree slenderness on wood properties in Scots pine. Part II: modulus of rupture and modulus of elasticity

ARKADIUSZ TOMCZAK, TOMASZ JELONEK, MARCIN JAKUBOWSKI, WITOLD PAZDROWSKI Poznań University of Life Sciences, Faculty of Forestry, Department of Forest Utilization

Abstract: The effect of tree slenderness on wood properties in Scots pine. Part II: modulus of rupture and modulus of elasticity. The aim of this work was analyse the variability in static modulus of rupture (MOR) and modulus of elasticity on static bending (MOE), in the trunks of pines. We put forward the hypothesis that the analysed properties will take higher values in the case of slender trunks, and additionally that the variation in the properties in slender trunks will be smaller. A study was made of 14 model trees from mature pine stands located in north-western Poland. All of the trees had similar DBH in bark of approximately 32 cm. The trees were divided into two groups: taller, with a mean height of 27.6 m, and shorter, with a mean height of 23.7 m. This selection led to groups of trees with trunks with lower (S74) and higher (S87) values of the slenderness ratio. Our results show statistically significant differences in MOR and MOE between the groups of trees. Higher values were recorded for the tall, more slender trees. The differences in the properties of wood from tall and short trees may suggest the conclusion that quality of material is of importance for a tree’s dynamics. It is hard to state how great is this importance, because the biomechanical system is a complex network of relationships and dependences.

Keywords: tree stability, height-to-diameter ratio, Pinus sylvestris

INTRODUCTION The trunk of a tree has a shape and structure appropriate to its physiological and mechanical functions (Mencuccini et al. 1997). Such a balance is essential for the survival of virtually all terrestrial plants. Its maintenance requires adaptive abilities, which have been acquired by plants in the course of their evolution. In the case of trees, survival depends chiefly on access to light and resistance to the action of physical factors such as wind or snow (Gardiner et al. 2016). Wind induces dynamic stresses which, if critical values are exceeded, may lead to breakage. Research comparing the properties of the wood of wind-damaged and undamaged trees has not supplied sufficient evidence to show that resistance depends on features of the material (Cameron and Dunham 1999; Meyer et al. 2008; Jakubowski et. al. 2014). Many researchers have concluded that the primary indicators of stability are features of the trunk and the crown (Petty and Swain 1985; Jelonek et al. 2013). One commonly used indicator of stability is the height-to-diameter ratio (HDR). Burshell and Huss (1997) constructed the following scale based on values of this ratio: HDR<45 – singly growing trees; HDR<80 – stable trees; 80100 – highly unstable trees. Wood is not a homogeneous material, and hence does not correspond to current mechanical models. On the other hand, the structure of plants cannot violate the laws of physics (Niklas 1992). The biomechanics and stability of trees have been the subject of many studies, often in the context of wind damage or the effect of the wind factor on trees’ growth and development (Spatz and Bruechert 2000; Tomczak et al. 2014). Experimental work is also carried out to simulate cases of damage (Peltola et al. 2000; Brüchert and Gardiner 2006). In some such studies, properties of the wood or features of its structure are used for the modelling of damage (Peltola et al. 1999). These are analysed chiefly in terms of the elasticity or rigidity of the trunk, assessed using the modulus of rupture. According to different authors, and at difference moisture, the static modulus of rupture of pine wood takes values of approximately 58.6 MPa (Mederski et al. 2015), 77.3 MPa (Wąsik et al. 2016) or 91.1 MPa (Gurau et al.

188 2008). The modulus of elasticity on static bending (MOE) according to Gurau et al. (2008) is approximately 11.20 GPa. Lindström et al. (2009), studying wood using non-destructive methods, estimated the MOE to be between 8.6 and 17.3 GPa, while Verkasalo (1992) reports values in a range from 9.7 to 19.1 GPa. Along the length of the trunk, the static modulus of rupture varies similarly to density, taking high values in the lower part of the trunk and low values in the top part (Tomczak et al. 2013), since the strength of wood is in correlation with its density (Vestøl and Høibø 2010). An interesting indicator of the technical value of wood is the ratio of strength to density. Theoretically, a material with high strength and low density has greater technical value. Tomczak (2013) analysed variation in the static modulus of rupture, as an indicator of quality, along the length of the trunk. It was found that the most technically valuable juvenile wood occurs between 20% and 40% of the height of the tree – a section in which the trunks of mature trees often breaks. The strength quality index was applied in a different fashion, from the perspective of the tree’s biomechanics, by Jelonek (2013). He proposed an index of stability that took account of a strength-based quality indicator describing properties of the wood tissue, and the slenderness of the tree. This is because in the biomechanical system, the most important factors for stability are properties of the wood and the tree architecture. The aim of this work is to analyse the variability in static modulus of rupture and modulus of elasticity on static bending, in the trunks of pines. We have hypothesis that the analysed properties will take higher values in the case of slender trunks, and additionally that the variation in the properties in slender trunks will be smaller.

MATERIALS A study was made of 14 model trees from mature pine stands located in north-western Poland. All of the trees had similar DBH in bark of approximately 32 cm. The trees were divided into two groups: taller, with a mean height of 27.6 m, and shorter, with a mean height of 23.7 m. This selection led to groups of trees with trunks with lower (S74) and higher (S87) values of the slenderness ratio. The differences were statistically significant (p-value<0.05). Other features of tree architecture and structural indices are described in the first part: The effect of tree slenderness on wood properties in Scots pine. Part I: Basic density and compression strength parallel to grain (Tomczak et al. 2016), along with a description and illustration of the experimental setup. For investigations of static modulus of rupture (MOR) and modulus of elasticity (MOE) five trunk sections were cut from each model tree. The sections were located at different heights: the first at breast height (DBH), and the remainder at points corresponding to 20%, 40%, 60% and 80% of the height of the tree. From each trunk section samples were cut out, located adjacently along radii running eastwards and westwards. Testing was carried out at a wood moisture greater than 30% (above the saturation point of the fibres), namely in conditions simulating those of a living tree. The limiting moisture of the membranes was obtained by immersing the samples in water until they attained dimensional stability, that is, until the increments in the individual dimensions of the samples measured at a time interval of 72 hours were equal to or less than 0.2 mm. The test of static modulus of rupture was carried out in accordance with the PN- 77/D-04103 standard. A sample with standardised dimensions (20x20x300 mm) was placed between two supports, and a load was applied at the midpoint of its length. The value of force at rupture was measured to an accuracy of 0.01 kN. Next the elastic modulus of the wood on static bending in a tangential direction was measured in accordance with PN-63/D-04117. During testing the material was subjected to an initial load of 100 N (with a deviation of 10 N), and after 30 s the initial deflection value was read. The force was then increased to 200 N (with a deviation of 10 N), and after a further 30 s the next deflection reading was made. The force was increased in steps of 100 N up to a value of 500N, and the deviation was read after

189 30 s in each case. The sample’s modulus of elasticity on static bending was calculated to the nearest 1 MPa (PN-63/D-04117).

RESULTS AND DISCUSSION Elasticity is the ability of materials to recover their shape (form) following the removal of external deforming forces. Rigidity is the deforming force necessary to produce unit displacement. As a result of deformations, stresses occur. In areas of the trunk cross-section where the stress is particularly high, the wood tissue is modified, chiefly through changes in the rate of thickness increments. The effect of swaying on the rate of increment in simulated conditions has been studied, among others, by Meng et al. (2006). Meanwhile, Tomczak et al. (2012) assessed trunk deformations in pine stands that were highly exposed to the wind. It was found that approximately 89% of the trees had a ovality trunk, the longer diameter being oriented parallel to the prevailing wind direction. The wind factor therefore has an impact on tree architecture. In our study, however, we did not find any effect of geographical orientation on wood properties. Slightly higher values were recorded on the eastward (sheltered) side of the trunk, but the differences were not statistically significant (Table 1). Similar conclusions are reported by Bascuñán et al. (2006), who compared the features and wood properties of trees of Pinus radiate at different ages. Independently of age, trees growing at different distances from the edge of the forest exhibited significant differences in height and trunk slenderness. There were also clear differences in mean values of dynamic modulus of elasticity (Ed). Moreover, a markedly higher value of Ed was found on the wind-facing part of the trunk than on the sheltered side, the differences becoming smaller as the distance of the tree from the edge of the forest increased. Zipse et al. (1998) carried out similar analysis for beech (Fagus sylvatica), finding in that case that the sheltered side was stronger and more rigid. Our results show statistically significant differences in MOR and MOE between the groups of trees. Higher values were recorded for the tall, more slender trees. Similar results were reported by Jelonek et al. (2012). Higher static modulus of rupture was found for the taller, slender trees. Moreover, greater strength was exhibited by trees with relatively shorter crowns, where the tree’s centre of mass was closer to the top (Jelonek et al. 2012). Also, Moore (2000) reported that trees with higher taper (lower ratio height-to-diameter) had higher maximum resistive bending moments than trees with low taper. During the growth of a tree, changes occur in its architecture. This is a genetically conditioned process. Additional stimuli are provided by changes in the tree’s surroundings, as a result of commercial thinning, for example. According to Kroon et al. (2008) the slenderness of trees in a stand may be affected by selection and breeding. Generally, for a short time after thinning, the risk of wind or snow damage to the remaining trees is high. It is only changes in the tree architecture and wood structure that bring about increased stability. Our analysis showed the mean values of MOR to be 46.1 MPa (S74) and 49.4 MPa (S87). The mean values of MOE were 4858 MPa (S74) and 5262 MPa (S87). The wood that underwent strength testing was wet, with moisture in excess of 30%. This can be expected to reflect the properties of wood in living trees. From each tree, five trunk sections were cut. This meant that we obtained real, and not modelled, values. Naturally, high values of MOR and MOE were found in the lower part of the trunk, and low values in the top part. The value of static and dynamic stresses decreases along the trunk, and hence in its upper part the wood has low density and reduced strength. Interesting results were obtained in the analysis of the changes in wood properties relating to stability. In tall, slender trees the values of MOR and MOE in the lower part of the trunk do not change much (MOR by only 0.4 MPa, and MOE by 184 MPa), while in shorter, more stable trees, the changes along the same section of the trunk were 6 MPa for MOR and 1013 MPa for MOE. There is thus a relationship between the

190 indicators of tree stability and the wood properties. These properties are determined by the composition and structure of the wood. Jelonek et al. (2015, 2016) found relationships between the indicators of tree stability and the ultrastructure of the wood tissue. In taller, slender trees the thickness of the walls of the tracheids in late wood is greater, while in the case of early wood it is smaller. Moreover the percentage content of crystalline cellulose is greater.

Table 1. Results of variance analysis modulus of rupture modulus of elasticity Source of Sum. sq. D. F-value p-value Sum. Sq. D. F-value p-value variance f. Mean sq. f. Mean sq. HDR 927,0 1 927,0 12,076 0,000573 1,9E+07 1 1,9E+07 15,20 0,000115 SN 11458,6 4 2864,6 37,320 0,000000 1,9E+08 4 4,8E+07 38,12 0,000000 GO 6,2 1 6,2 0,081 0,776697 2,3E+06 1 2,3E+06 1,80 0,180991 HDR*SN 680,4 4 170,1 2,216 0,066792 1,4E+07 4 3,5E+06 2,78 0,026601 HDR*GO 3,8 1 3,8 0,049 0,824695 1,2E+06 1 1,2E+06 0,96 0,328958 SN*GO 373,8 4 93,5 1,217 0,302968 6,1E+06 4 1,5E+06 1,21 0,305867 HDR*SN*GO 227,1 4 56,8 0,740 0,565472 6,0E+06 4 1,5E+06 1,18 0,317474 Error 27786,9 362 76,8 4,6E+08 362 1,3E+06

S74 S87 Table 2. Mean modulus of rupture [MPa] from different SN mean n SD VC mean n SD VC parts of trunk DBH 54,3 53 9,2 16,94 53,4 63 11,3 21,16 20% 48,4 46 8,2 16,94 53,8 43 9,6 17,84 40% 42,4 40 8,0 18,87 46,9 44 8,3 17,70 60% 38,0 31 5,8 15,13 42,6 28 5,3 12,44 80% 37,1 16 9,5 25,71 41,5 18 5,9 14,22 In total 46,1 186 10,4 22,56 49,4 196 10,3 20,85 Legend: n – number of samples, SD – standard deviation, VC – variability coefficient

S74 S87 Table 3. Mean modulus of elasticity [MPa] from different SN mean n SD VC mean n SD VC parts of trunk DBH 6030 53 1116 18,50 5854 63 1576 26,92 20% 5017 46 849 16,93 5670 43 1309 23,08 40% 4361 40 987 22,64 4773 44 1125 23,57 60% 3944 31 793 20,10 4679 28 866 18,50 80% 3531 16 777 22,01 4327 18 867 20,04 19 In total 4858 186 1276 26,26 5263 1393 26,47 6 Designations as in Table 2

Table 4. Differences between parts of trunk modulus of rupture modulus of elasticity

S74 S87 S74 S87

SN relation absolute relative absolute relative absolute relative absolute relative DBH - 20% -5,9 -10,9 0,4 0,75 -1013,1 -16,8 -184,1 -3,1 20% - 40% -6,0 -12,4 -6,9 -12,83 -656,2 -13,1 -896,7 -15,8 40% - 60% -4,4 -10,4 -4,3 -9,17 -417,2 -9,6 -93,8 -2,0 60% - 80% -0,9 -2,4 -1,1 -2,58 -412,8 -10,5 -352,5 -7,5 Legend: absolute [MPa], relative [%]

191

The differences in the properties of wood from tall and short trees may suggest the conclusion that quality of material is of importance for a tree’s dynamics. It is hard to state how great is this importance, because the biomechanical system is a complex network of relationships and dependences. This is shown by the example of the MOE value, where an interaction effect is observed, the only combined effect relating to slenderness and variability of wood (Table 4).

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192 15. NIKLAS K. J., 1992: Plant biomechanics: An engineering approach to plant form and function. University of Chicago Press, Chicago, Illinois, U.S. 16. MEDERSKI P. S., BEMBENEK M., KARASZEWSKI Z., GIEFING D. F., SULIMA-OLEJNICZAK E, ROSIŃSKA M., ŁĄCKA A., 2015: Density and mechanical properties of Scots pine (Pinus sylvestris L.) wood from seedling seed orchad. Drewno, 58(195): 117 – 124. DOI: 10.12841/wood.1644-3985.123.10 17. MENCUCCINI M., GRACE J. FIORAVANTI M., 1997: Biomechanical and hydraulic determinants of tree structure in Scots pine: anatomical characteristics. Tree Physiology, 17(2): 105-113. 18. MENG S. X., LIEFFERS V. J., REID D. E., RUDNICKI M., SILINS U., JIN M., 2006: Reducing stem bending increases the height growth of tall pines. Journal of Experimental Botany, 57(12): 3175 – 3182. 19. MEYER F. D., PAULSEN J., KÖRNER CH., 2008: Windthrow damage in Picea abies is associated with physical and chemical stem wood properties. Trees 22: 463−473. 20. MOORE, J. R., 2000: Differences in maximum resistive bending moments of Pinus radiata trees grown on a range of soil types. Forest Ecology and Management, 135(1): 63-71. 21. PETTY J. A., SWAIN C., 1985: Factors influencing stem breakage of conifers in high winds. Forestry 58(1): 75−84. 22. PELTOLA H., KELLOMAKI S., HASSINEN A., GRANANDER M., 2000: Mechanical stability of Scots pine, Norway spruce and birch: an analysis of tree−pulling experiments in Finland. Forest Ecology and Management, 135: 143−153. 23. PELTOLA H., KELLOMÄKI S., VÄISÄNEN H., IKONEN V. P., 1999: A mechanistic model for assessing the risk of wind and snow damage to single trees and stands of Scots pine, Norway spruce, and birch. Canadian Journal of Forest Research, 29(6): 647-661. 24. SPATZ H. C., BRUECHERT F., 2000: Basic biomechanics of self-supporting plants: wind loads and gravitational loads on a Norway spruce tree. Forest Ecology and Management, 135(1): 33-44. 25. TOMCZAK A., JELONEK T., PAZDROWSKI W., 2012: Ekscentryczność pni sosny zwyczajnej (Pinus sylvestris L.) z drzewostanów silnie eksponowanych na wiatr. Forestry Letters, 103: 41 – 46. 26. TOMCZAK A., JELONEK T., PAZDROWSKI W., 2013: Bending strength of Scots pine wood – relationships between values calculated at different heights of the trunk. Ann. Warsaw Agricult. Univ. – SGGW, For. and Wood Technol. 84: 247 – 252. 27. TOMCZAK A., JELONEK T., JAKUBOWSKI M., GRZYWIŃSKI W., SZABAN J., 2016: The effect of tree slenderness on wood properties in Scots pine. Part I: Basic density and compression strength parallel to grain. Ann. WULS - SGGW, For. and Wood Technol [in press]. 28. WĄSIK R., MICHALEC K., MUDRYK K., 2016: Variability in static bending strength of the “Tabórz” Scots pine wood (Pinus sylvestris L.). Drewno, 59(196): 153 – 162. DOI: 10.12841/wood.1644-3985.132.11. 29. VERKASALO E., 1992: Relationships of the modulus of elasticity and the structure of Finnish Scots pine. Silva Fennica, 26(3): 155–168. 30. VESTØL G. I., HØIBØ O., 2010: Bending strength and modulus of elasticity of Pinus sylvestris round timber from southern Norway. Scandinavian Journal of Forest Research, 25(2): 185 – 195. 31. ZIPSE A., MATTHECK C., GRÄBE D., GARDINER B., 1996: The effect of wind on the mechanical properties of the wood of beech (Fagus sylvatica L.) growing in the

193 borders of Scotland. Arboricultural Journal: The International Journal of Urban Forestry, 22(3): 247 – 257. DOI: 10.1080/03071375.1998.9747208

LIST OF STANDARDS 1. PN-63/D-04117. Fizyczne i mechaniczne właściwości drewna. Oznaczanie współczynnika sprężystości przy zginaniu statycznym. 2. PN−77/D−04103. Drewno. Oznaczanie wytrzymałości na zginanie statyczne.

Streszczenie: Właściwości drewna sosen zróżnicowanych pod względem smukłości pnia. Część II. Wytrzymałość na zginanie statyczne i moduł sprężystości. Celem pracy była analiza zmienności wytrzymałości na zginanie statyczne (MOR) i modułu elastyczności przy zginaniu statycznym (MOE) w pniach sosen. Założono, że wartości analizowanych właściwości będą wyższe w smukłych pniach. Dodatkowo, że zmienność właściwości w smukłych pniach będzie mniejsza. Badania wykonano w dojrzałych drzewostanach sosnowych, na czternastu drzewach modelowych. Wszystkie drzewa miały podobną pierśnicę (DBH) – około 32 cm w korze. Drzewa podzielono na dwie grupy: wyższe i niższe. Średnia wysokość drzew wyższych to 27,6 m, a niższych 23,7 m. W ten sposób wybrano drzewa z pniami mniej (S74) i bardziej smukłymi (S87). Drzewa wysokie, bardziej smukłe, charakteryzowały się drewnem bardziej sprężystym, o wyższej wytrzymałości na zginanie statyczne. Wysokie wartości MOR i MOE stwierdzono w dolnej części pnia, niskie w części wierzchołkowej. Wielkość naprężeń statycznych i dynamicznych zmniejsza się wzdłuż pnia, dlatego w jego wierzchołkowej części drewno ma niską gęstości i mniejszą wytrzymałość. U drzew wysokich, smukłych MOR i MOE w dolnej części pnia zmieniają się nieznacznie. MOR zaledwie o 0,4 MPa, a MOE o 184 MPa, podczas gdy u drzew niższych, stabilniejszych, zmiana na tym samym odcinku pnia wynosi w przypadku MOR 6 MPa i MOE 1013 MPa. Drzewa o smukłych pniach charakteryzują się więc drewnem o wyższej jakości technicznej i większej jednorodności.

Corresponding author:

Arkadiusz Tomczak Poznan University of Life Sciences, Faculty of Forestry, Department of Forest Utilisation Wojska Polskiego 71A, 60 – 625 Poznań E-mail: [email protected]

194 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 195-199 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Comparative compressive strength tests of solid elements and elements glued of small-sized fir wood

ANDRZEJ TOMUSIAK, IZABELA BURAWSKA, ANDRZEJ CICHY Department of Technology and Entrepreneurship in Wood Industry, Faculty of Wood Technology, Warsaw University of Life Sciences - SGGW

Abstract: Comparative Compressive Strength Tests of Solid Elements and Elements Glued of Small-Sized Fir Wood. The work consisted in testing the compressive strength of fir wood elements - both solid and glued from small fragments. The tests have shown that the elements glued from small fragments of waste materials are more resistant, and their compressive strength parallel to grain is ca. 25% higher than in case of solid wood elements made of the same wood species.

Keywords: compression, strength tests, fir wood

INTRODUCTION The processes of wood production and processing go together with a high amount of waste material being generated. According to estimations, about 30-40% of entire production corresponds to waste. The share of sawmills in the supply of waste wood materials amounts to over 63%. Waste wood from sawmills consists, mainly, of fragmented wood in the form of offcuts, wanes, root swellings, as well as shavings and bark. Out of the remaining 37% of wood waste, 14% corresponds to the furniture industry (waste consisting of engineered wood materials and solid wood, wood dust, sawdust and shavings) and another 13% to the engineered wood panel industry (fragments of solid wood, derivative wood products, shavings, sawdust and bark). Due to the significant amounts of wooden waste materials, it is desirable to try and make use of them, eg. by gluing them together in an adequate way and using them further in construction or for furniture making.

SCOPE OF RESEARCH The scope of research includes: • specifying the cross-section dimensions and the height of the samples, • specifying the mass and density of the samples, • specifying the water content of the samples with the oven dry method, • measuring the maximum force (load of rupture), • specifying the compressive strength.

RESEARCH MATERIAL The research material consisted of fir posts prepared by the Golbalux sp. z o.o. company. The posts had the following nominal dimensions: cross-section 160 mm x 160 mm and height of 456 mm. Considering the need to avoid a possible buckling of the cross-section that could affect the tests, the ratio of the height of the sample's section to the smaller side of the section was 2.85. The ends of the posts were smoothly polished, parallel to one another and perpendicular to their longitudinal axis, in accordance with the recommendations of the EN 408:2012 standard. The posts in group A were made of solid wood. The posts in group B were glued (in three dimensions - spatially) from an appropriate number of wooden elements in every plane,

195 until the required nominal cross-section and height dimensions were reached. The elements were joined together on their ends with finger joints. Each group consisted of 24 samples, in order to carry out a statistical analysis. WORK METHODOLOGY The tests were carried out with the use of a universal strength testing machine - Instron 8806 with the range of 2.500 kN, in the Water Centre at the Faculty of Construction and Environmental Engineering of the Warsaw University of Life Sciences-SGGW. Samples from both groups were subjected to compressive strength. The force was applied along the longitudinal axis, with the use of a special head that permitted to apply the compressive load and avoid bending at the same time (Fig. 1), with the speed of 3mm/min. The movement speed of the strength testing head was adjusted in such a way, as to reach the maximum load value during 90 ± 30 s from the beginning of the test. The head was protected against diverging from the longitudinal axis, so that the direction of the compressive force was in line with the longitudinal axis of the sample. The water content of wood was determined with the oven dry method, by cutting samples of 40 x 40 x 100 mm from every tested element. Afterwards, the water content was calculated in [%] from the formula (1):

(1) = ( − )/

where: mw – mass of a wet sample [g], ms – mass of a dry sample [g]. Density before drying was calculated from the formula (2):

(2) =

where m – total mass of the tested element [kg], V – total volume of the tested element [m3].

Figure 1. Sample during compression strength tests

Compressive strength in parallel to grain was calculated for samples from both groups from the formula (3):

196 (3) , =

where: compressive strength of the samples [MPa], , − maximum load [N], − − sample dimension in radial direction [mm], − sample dimension in tangential direction [mm].

For the purpose of comparison in the analysis of test results, the value of compressive strength parallel to grain of posts whose moisture content was = W, was recalculated and translated into the value of compressive strength parallel to grain at a fixed water content value of 12% ( ). In view of significant differences in water content in case of posts from ,, group A (19.1% on average) and group B (11.7% on average), the compressive strength value parallel to grain was recalculated and translated into a value corresponding to the water content of 12% (4).

(4) ,, = , ∙ (1 + 0.03 ∙ ( − 12))

Due to significant differences in the water content of individual posts, their density was also recalculated in order to correspond to the value of water content = 12% (5). (5) =∙(1−0.005∙ ( − 12))

Afterwards, we calculated the characteristic value of compressive strength ( in ) parallel to grain for samples from both groups, using the formula (6).

∑ ∙, (6) = min(1.2 ∙ ,, ; ) ∙

where: min 5% quantile of compressive strength [MPa], ,, − 5% quantile of compressive strength [MPa] for i - sample [MPa], , − correction coefficient equal to 1.0, − − number of samples.

TEST RESULTS The results of water content, destructive force and compressive strength tests, together with the cross-section dimensions, height, mass and density of the samples have been presented in Tables no. 1 and 2.

Table 1. Compressive strength test results for posts in group A (solid wood posts)

Fmax ρ σc,0 W ρW=12 σc,0,12 Parameter [kN] [kg/m3] [MPa] [%] [kg/m3] [MPa] average 649.5 500 25.5 19.1 482 30.8 standard deviation 102.4 77 4.1 2.6 75 4.5 coefficient of variation 15.8 15 16.1 13.5 16 14.7 5% quantile 557.7 414 21.8 16.5 402 25.6 characteristic value 25.6

197

Table 2. Compressive strength test results for posts in group B (glued posts)

Fmax ρ σc,0 W ρW=12 σc,0,12 Parameter [kN] [kg/m3] [MPa] [%] [kg/m3] [MPa] average 997.8 490 39.0 11.6 491 38.5 standard deviation 77.8 26 3.0 0.4 26 3.0 coefficient of variation 7.8 5 7.8 3.1 5 7.7 5% quantile 878 455 34.3 11.1 455 33.4 characteristic value 33.4

Table 3. Comparison of the average density value and compressive strength for groups A and B ρW=12 σc,0,12 Group A 482 30.8 Group B 491 38.5 change 1.8 24.9

SUMMARY The tests have shown that the average compressive strength of posts made of glued wood is almost 25% higher in comparison with solid wood posts. Additionally, in case of glued posts, the coefficient of variation of compressive strength is two times smaller than in case of solid wood posts. The increase in strength is definitely due to a more homogeneous wood structure, resulting from the elimination of wood defects that affect negatively the strength value. The average density of samples in groups A and B was similar, so density was not a factor that would condition the variation in compressive strength. Therefore, it can be concluded that by gluing together small elements of wood waste, quality structural elements with larger section can be obtained and used for wooden construction purposes.

REFERENCES 1. EN 408:2012. Timber structures. Structural timber and glued laminated timber. Determination of some physical and mechanical properties. 2. KRZYSIK F. 1957: Nauka o drewnie Wydawnictwo PWRiL, Warszawa 3. MIELCZAREK Z. 1994: Budownictwo drewniane, Wydawnictwo Arkady, Warszawa

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Streszczenie: Badania porównawcze wytrzymałości na ściskanie elementów litych i klejonych przestrzennie z drewna jodłowego małowymiarowego. W pracy badano wytrzymałość na ściskanie elementów litych i klejonych przestrzennie z drewna jodłowego małowymiarowego. Badania wykazały, że elementy klejone przestrzennie z drewna odpadowego małowymiarowego posiadają ok. 25 % większą wytrzymałość na ściskanie wzdłuż włókien niż elementy lite wykonane z tego samego gatunku drewna.

Corresponding authors:

Izabela Burawska email: [email protected] Andrzej Cichy email: [email protected] Andrzej Tomusiak email: [email protected] Department of Technology and Entrepreneurship in Wood Industry Faculty of Wood Technology Warsaw University of Life Sciences - SGGW 02-776 Warsaw, ul. Nowoursynowska 159 Poland

199 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 200-205 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The impact of the pine annual ring width on the screw withdrawal resistance

ANDRZEJ TOMUSIAK1, MAREK GRZEŚKIEWICZ1, ANDRZEJ MAZUREK2

1 Department of Technology and Entrepreneurship in Wood Industry, Faculty of Wood Technology, Warsaw University of Life Sciences - SGGW, 159 Nowoursynowska St., 02-776 Warsaw

2 Department of Wood Science and Wood Preservation, Faculty of Wood Technology, Warsaw University of Life Sciences - SGGW, 159 Nowoursynowska St., 02-776 Warsaw

Abstract: This paper presents investigation of the impact of the pine wood (Pinus sylvestris L.) annual ring width on the screw withdrawal resistance. For tests samples made of 2-layer laminated pine wood were used: Solid lam and Lam FJ. Samples made of Solid Lam were divided on to the three sets with different annual ring width: slow a. r. w. 0.64-2.5mm, medium a. r.w. 2.5-3,5mm and fast a. r. w. 3.5-4.6mm. Samples made of Lam FJ varied in annual growth ring. Screws used in industry practice were screwed in tested samples. The screw withdrawal resistance were determined using empiric method according PN_EN 1382:2000. Characteristic screw withdrawal resistance were calculated according Eurocode 5. Correlations withdrawal resistance and wood density were determined for each wood sample set and for all samples. As a result of test it was found that for all samples coefficient of correlation of withdrawal resistance and wood density was 0.71. and it was found that growth ring width does not influence withdrawal resistance and the differences between average values are not statistically significant for the same class of wood. Tested pine wood fulfils the requirements of Eurocode 5.

Keywords: pine wood ring, screw withdrawal resistance

INTRODUCTION The aim of the study consists in determining how growth ring width influences the screw withdrawal resistance - self-drilling screws. The scope of the study includes: screw withdrawal resistance determination in accordance with the PN-EN 1382:2000 standard, wood sample density determination, determination of the moisture content of the tested wooden elements with the use of the oven-dry method.

MATERIALS AND METHODS The tested wooden elements were made of European pine wood. The first batch of elements was glued of two solid wood elements at the height of the section (Solid lam), the second one was glued with finger joints (in length) and then glued in height (Lam FJ). The influence of growth ring width on fastener withdrawal capacity was tested on standard samples - Figure 1. Due to the fact that the samples were cut out from elements that were previously sawn by the Contracting Party, it was not possible to identify a purely tangential or radial section. In all the samples the section was radially-tangential and this is the section that has been tested. We cut out samples of every element that was glued of two solid elements (Solid lam) in the way shown in Fig. 1 the samples fulfilled the standard requirements. Later, we determined the growth ring width of all elements and divided them into three groups. The first one included wood of slow growth with growth ring width from 0.64-2.5 mm - about 52 samples; the second group included about 84 samples with medium growth ring width from 2.5-3.5 mm; and the third group of samples had wide growth rings from 3.5-4.76 mm and about 53 samples. Such a high number of samples made the test results more reliable. It should be noted that in accordance with Eurocode 5, the number of tests should not be smaller than 30 pcs. We also prepared a control group of about 40 samples with the same dimensions made of elements glued first in their length and then in height (Lam FJ). The screws used in industry practice are presented in Figure 2.

200

Figure 1. Sample dimensions and position of fasteners 3 mm diameter and 40 mm length, proportions in sample dimension according PN-EN 1382:2000 standard.

Figure 2.1 Characteristics of the fasteners (screws) used for tests

The screw withdrawal resistance was tested in accordance with the PN-EN 1382:2000 standard: "Timber Structures. Test methods. Withdrawal capacity of timber fasteners." in accordance with the above-mentioned standard, withdrawal capacity is defined by the following equation (1): F  N  f = max (1) d × l mm2  p   2 where: f- withdrawal resistance [N/mm ], Fmax- maximum force at withdrawal [N], d- diameter of the smooth part of the round nail or [mm], lp- fastener penetration together with the tip [mm]. Sample moisture content was determined in accordance with the EN 131831-1 standard on samples with dimensions of 53x40x105 mm in the area of the fastener. The wood of the samples was free from resin pockets. The moisture content of wood was determined with the oven-dry method and calculated with the use of the equation (2). m − m w = w s ⋅100% (2) ms where: w – moisture content of the tested wooden elements [%], mw – wet sample mass [kg], ms – dry sample mass [kg]. The drying process was carried out in a drying chamber in the temperature of about 105ºC, in accordance with the above-mentioned standard. Additionally, wet wood density was specified as the ratio of wet mass to volume, using the formula (3):

201 mw 3 Qw = [kg/m ] (3) Vw where: Q - wet wood density [kg/m³], m - wet sample mass [kg], w w Vw- wet sample volume [m³]. For the sake of comparison, the characteristic values of selected parameters were also calculated on the basis of test results (DD ENV 1995-1-1:1994 standard), with the use of the following equation (4):

k k = k1 × m x)( (4) where: k1 - coefficient depending on the number of trials and the coefficient of variation (from the table), m(x) – mean value of the tested parameter.

RESULTS AND DISCUSSION Table 1 presents the mean values of withdrawal resistance for samples cut from Solid lam elements in three groups of different growth ring width; and for samples cut from Lam FJ elements without division into growth ring types. Table 2 presents the characteristic values of wood density and fastener withdrawal resistance calculated using the equation (5).

Table 1. Withdrawal resistance [N/mm²] of self-drilling screws (diameter 3 mm) - presentation with statistical measures. Source material Solid lam Lam FJ Growth ring width slow annual medium annual fast annual variable growth growth growth 0.64-2.5mm 2.5-3.5mm 3.5-4.76mm Categories Min resistance [N/mm2] 21.4 26.8 28.1 29.1 Max resistance [N/mm2] 47.7 41.6 42.3 42.4 Average resistance [N/mm2] 33.9 33.0 34.0 34.4 Standard deviation [N/mm2] 5.03 3.56 3.55 3.19 Coefficient of variation [%] 14.8 10.8 10.5 9.3 Moisture content [%] 7.5 7.5 7.6 8.1 Density [kg/m3] 474 446 455 484

Table 2. Characteristic values of withdrawal resistance and wood density Sample kind Characteristic value Characteristic value (kind of material and growth ring width) of withdrawal resistance of wet wood [N/mm²] [kg/m³] Solid lam slow annual growth 26.7 373 Solid lam medium annual growth 26.0 351 Solid lam fast annual growth 26.8 358 Lam FJ variable annual growth 27.1 377

The average withdrawal resistance of screws tested in samples obtained from Solid lam elements in the group of slow annual growth wood (thin annual rings) amounted to 33.91 MPa; in the group of medium annual growth wood - 33.02 MPa; and in fast annual growth (widest annual rings) - 33.97 MPa. The obtained results had the following coefficients of variation: 14.8%, 10.8% and 10.5%. The differences in average withdrawal resistance values were not statistically significant. Therefore, growth ring width does not affect the withdrawal resistance within the same class of wood. Moreover, Table 2 shows that the average characteristic density of Solid lam wood was 361 [kg/m3], so the analyzed material can be graded as class C24 (> 350

202 and < 370 kg/m3) in accordance with EN338: 2012. On the other hand, Lam FJ wood should be graded as class C27 (> 370 and < 380 kg/m3). The test of statistical significance of withdrawal resistance differences between medium growth Solid lam wood and glued Lam FJ wood shows statistically significant differences between the average values, which is due to the lower density of medium annual growth wood - 351 kg/m³, at the limit of class C24. We also carried out a test of significance of the differences between the average withdrawal resistance values of Solid lam and Lam FJ sets, which showed that these differences are not statistically significant. Figures 3 show the regression equations of the correlation between withdrawal resistance and density for all tested samples. The obtained correlation coefficients (over 0.5) show that the correlation is high and, in case of samples cut from slow growth Solid lam the coefficient amounts to 0.80, medium growth:0.82 and fast growth 0.70. In case of samples cut from Lam FJ, the correlation coefficient is only 0.51, which is due to the fact that sample density has a small range of variation and there may be different results for the same density. We also specified the correlation coefficient for Solid lam samples: it amounted to 0.76; while for all the tested samples it was 0.71. The tests suggest that wood density is an important factor that influences the withdrawal resistance of screws. The Eurocode 5 standard also states that it is the basis factor of increase of the withdrawal resistance. in accordance with the above- mentioned standard, the withdrawal resistance of a screw is calculated via the following equation (5):

 N  f = 52,0 d − 5,0 × l − 1,0 × ρ 8,0 (5) ,kax ef k  2  mm  where: fax,k – the characteristic withdrawal resistance of the screw in case of withdrawal perpendicular to grain [N/mm2], d- external diameter of the threaded part of the screw [mm], lef- depth of penetration of the profiled part of the shaft from the tip's side [mm], ρk – characteristic density of wood [kg/m³]

20 y = 0,0733x - 0,1858 10 R = 0,71

Withdrawalresistance[MPa] 0 350 400 450 500 550 600 Density [kg/m3]

Figure 3. Relation between screw withdrawal resistance and wood density for all the tested samples, i.e.: slow, medium and fast annual growth samples cut of Solid lam elements and Lam FJ elements glued in length and in height, n=258

By filling in the data for our case, we can calculate the characteristic value on the basis of this equation, and it's equal to ca. 21 MPa on average; so it's smaller than the value obtained

203 on the basis of withdrawal capacity tests. This allows us to conclude that the withdrawal resistance of the tested screws meets the requirements of the Eurocode 5 standard and even exceeds them by about 5.2 MPa. In general, we can assume that the increase of wood density by 10% causes an increase of withdrawal resistance by about 6% (Babecki, 2011). It should be noted that the moisture content of the tested wood samples was comparable - about 8%. Moreover, the research conducted by Babecki [2011] also shows that the direction of screws in the wood (in parallel or in perpendicular to grain) is not statistically significant and does not matter in practice.

CONCLUSIONS The study has revealed that: 1. Within the same class of wood, the growth ring width does not influence withdrawal resistance and the differences between average values are not statistically significant. 2. The characteristic withdrawal resistance determined on the basis of the tests is higher than the resistance calculated through the equation taken from the standard, which means that the tested screw fulfils the requirements of Eurocode 5. 3. The tests have proven that fastener withdrawal capacity depends, most of all, on wood density, which is also confirmed by the equation (14); and the correlation coefficient was very high for all the analyzed samples and amounted to 0.71.

REFERENCES 1. BABECKI R.,2011: Badanie nośności na wyciąganie wkrętów zwykłych i samowiercących oraz gwoździ gładkich w drewnie sosnowym [fastener withdrawal capacity tests for standard and self-drilling screws and smooth nails in pinewood] Master thesis at the Faculty of Wood Technology, Warsaw University of Life Sciences (SGGW) 2. OSTASIEWICZA S., RUSNAK Z., SIEDLECKA U. 2000: Statystyka. Elementy teorii i zadania. [Statistics. Elements of theory and problems] Wydawnictwo Naukowe PWN, Warsaw 3. Standards 4. DD ENV 1995-1-1:1994 Eurocode 5. Design of timber structures. Part 1.1 General rules and rules for buildings. 5. PN-EN 1382:2000 Timber Structures. Test methods. Withdrawal capacity of timber fasteners.

204

Streszczenie: Wpływ szerokości rocznych przyrostów drewna sosnowego (Pinus sylvestris L.) na wytrzymałość na wyciąganie wkrętów. Do badań wykorzystano drewno sosnowe (Pinus sylvestris L.) klejone warstwowo (dwie warstwy): klejonkę z drewna litego (Solid lam) i klejonkę z segmentów drewna litego łączonych na długość za pomocą złączy wieloklinowych (Lam FJ). W elementach wykonanych z Solid lam, podzielonych na zbiory o zróżnicowanej słoistości, wąskosłoiste drewno, o przyrostach w granicach 0.64-2.5mm, średniosłoiste drewno, 2.5-3,5mm, szerokosłoiste 3.5-4.6mm, osadzano samowkręcające się wkręty do drewna, stosowane w praktyce przemysłowej. W przypadku próbek wykonanych z Lam FJ charakteryzowały się one zróżnicowaną słoistością. Określono empirycznie wytrzymałość na wyciąganie wkrętów według PN-EN 1382:2000. Obliczono wytrzymałości charakterystyczne wkrętów na wyciąganie według Eurocode 5. Określono korelacje pomiędzy wytrzymałością wkrętów na wyciąganie a gęstością dla poszczególnych zbiorów i dla wszystkich badanych próbek. W wyniku badań stwierdzono wysoką korelację pomiędzy wytrzymałością na wyciąganie wkrętów i gęstością drewna (R=0.71 dla wszystkich badanych próbek) i nie stwierdzono statystycznie istotnego wpływu słoistości na wytrzymałość na wyciąganie w obrębie tej samej klasy drewna. Badane drewno sosnowe spełniało wymagania stawiane przez Eurocode 5 dla drewna konstrukcyjnego.

Corresponding author:

Andrzej Tomusiak Department of Technology and Entrepreneurship in Wood Industry Faculty of Wood Technology Warsaw University of Life Sciences – SGGW 159 Nowoursynowska St. 02-776 Warsaw, Poland email: [email protected] phone: +48 22 59 38 540

205 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 206-212 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Аспекты влияния органо-минеральных покрытий на огнестойкость древесины

АЛЕКСЕЙ ЦАПКО

Кафедра технологии деревообработки Национального университета биоресурсов и природопользования Украины – НУБиП Украины

Abstract: Aspects influence of organo-mineral ceiling on fire wood. The results of studies and wood burning fire protection established influence on the rate and depth of charring, and correspondingly to reduce the working section of a wooden structure at high exposure.

Keywords: wood, coating, fireproofing efficiency, charring, burning, fire wood.

ВВЕДЕНИЕ Причиной выхода из строя деревянных конструкций является уменьшение их рабочего сечения в результате обугливания при горении и последующего разрушения. По мере уменьшения рабочего сечения деревянной конструкции, напряжение от нормативной нагрузки увеличивается, и при достижении ими предела прочности древесины, проходит обрушение конструкции. Повысить уровень пожарной безопасности объектов, где используются строительные конструкции из древесины, возможно с помощью ее огнезащитной обработки, суть которой заключается в предоставлении древесине способности противостоять действию пламени и распространению пламени по поверхности [1].

МЕТОДИКА ИССЛЕДОВАНИЯ Для расчета предела устойчивости деревянных конструкций в общем случае необходимо решение двух задач: теплотехнической и прочностной [2]. Решение теплотехнической задачи устойчивости деревянных конструкций заключается: а) в определении времени (τ), с начала теплового воздействия пожара к возгоранию древесины в конструкции; б) в определении изменения рабочего сечения деревянной конструкции после возгорания древесины при пожаре за счет процесса ее обугливания. Решение прочностной задачи устойчивости, применительно к деревянным конструкциям, заключается: а) в определении изменения соответствующих напряжений в расчетных сечениях конструкций от нормативных нагрузок в зависимости от изменения рабочих связей деревянной конструкции за счет обугливания древесины после ее воспламенения при пожаре; б) в проверке условий прочности деревянной конструкции на воздействие соответствующих нормативных нагрузок, с учетом изменения напряжений от этих нормативных нагрузок в зависимости от времени горения древесины к потере конструкцией несущей способности. Изменение напряжений растяжения σр(τ) центрально-растянутых элементов, в зависимости от времени их горения при пожаре τ следует определять из выражения:

206 N н σ p ()τ = , (1) Fнт ()τ где: Nн - продольная сила от нормативных нагрузок, Н; Fнт(τ) - площадь поперечного сечения элемента, нетто, в зависимости от времени горения при пожаре τ, м2.

Время τр - от начала возгорания элемента конструкции при пожаре к потере им несущей способности определяется из условия: если

σ p (τ ) ≥ R p . (2) Изменение напряжений сжатия σс(τ) центрально-сжатых элементов, в зависимости от времени их горения при пожаре τ следует определять: а) по прочности из условия:

N н σ c ()τ = (3) Fнт ()τ б) по устойчивости из условия:

N н σ c ()τ = (4) ()()τϕ ⋅ Fс τ где: φ(τ) - коэффициент продольного изгиба, определяемый с учетом изменения рабочего сечения элемента в момент времени τ его горения; Fс(τ) - расчетная площадь поперечного сечения элемента, с учетом его обугливания.

Время τ от начала возгорания элемента при пожаре к потере им несущей способности, определяется из условия: если

σ p (τ ) ≥ Rc . (5) Изменение изгибающих напряжений σв(τ) и скалывающих напряжений σск(τ) изгибаемых элементов, в зависимости от времени τ их горения при пожаре, определяются из выражений:

M н σ в ()τ = , (6) W р ()τ

Qн ⋅ S бр (τ ) σ ск = , (7) J бр ()()τ ⋅b τ где: Мн - изгибающий момент в расчетном сечении от нормативных нагрузок, кН·м; Wр (τ) - момент сопротивления рабочего сечения элементов, в зависимости от времени горения при пожаре, м3; Qн - поперечная сила в расчетном сечении от нормативных нагрузок, кН; S (τ) - статический момент, брутто, в зависимости от времени τ горения расчетного сечения при пожаре, м3; Jбр (τ) - момент инерции расчетного сечения, масса, в зависимости от времени τ горения расчетного сечения при пожаре, м4; b (τ) - ширина элемента, в зависимости от времени τ его горения при пожаре, м.

Время τ от начала возгорания элемента при пожаре к потере им несущей способности, определяется из условий: а) прочности на изгиб

207 если

σ в (τ ) ≥ Rв , (8) б) прочности на скалывание если

σ ск (τ ) ≥ Rск . (9)

РЕЗУЛЬТАТЫ По экспериментальным данным, средняя скорость обугливания древесины в конструкциях такова: массивные элементы сечением не менее 150х150 мм - 0,6 мм/мин., дощатая обшивка, перегородки из досок толщиной 15-20 мм - 0,8÷1,0 мм/мин. [3]. Эти данные относятся к древесины необработанной защитными веществами. Что касается защищенной древесины то значение скорости обугливания неизвестные и зависят от природы защитных покрытий и их свойств. Прогнозирование средней скорости обугливания для древесины предложено проводить по зависимости [4]: m Vo = , (9) ρ w где m – скорость выгорания древесины (скорость потери массы), кг/(м2∙с); 3 ρw – плотность древесины в сухом состоянии (влажность 10÷12%), кг/м .

Для необработанных образцов максимальная скорость выгорания составляет 8,2 г/(м2•с). Показатели скорости развития и прекращения горения для древесины обработанной органо-минеральным покрытием, существенно отличаются от предыдущего, а именно, при количестве защитного средства 260 г/м2 достигается минимальная скорость выгорания 2,11 г/(м2•с) [5]. Так, плотность поверхностного слоя необработанной древесины составляет 460÷480 кг/м3, а для огнезащищенной – 500÷510 кг/м3, а соответственно, скорость обугливания древесины, которая определена по (9), составляет для защищенной ниже 0,000236 м/мин. и соответственно для необработанной - 0,00096 м/мин. Рассмотрим деревянную стойку из цельной древесины. Материал стойки - сосна первого сорта. Сечение bхh=0,22х0,20 м. Влажность древесины - 10÷12 %, нагрузка на стойку Nн = 740 кН. Варианты защиты: а) без защиты; б) огнезащита органо-минеральным покрытием. Задаем последовательные моменты времени горения деревянной стойки при пожаре, определяем рабочий сечение стойки (Fс(τ)) и напряжения сжатия (σс(τ)) (рис. 1). Определяем время τ от начала возгорания деревянной стойки при пожаре к потере ею

несущей способности по (1), согласно которой выполняются условия σ p (τ ) ≥ Rc = 25 МПа. Это условие выполняется для необработанной древесины на 40 минуте, а для обработанной - сдвигается более чем на 120 минут. Рассмотрим деревянную двускатную дощатую балку покрытия. Пролет балки 10 м; ширина балки 17 м; высота в середине пролета hс = 1,3 м; высота на опоре - hоп = 0,8 м; материал - сухие сосновые доски второго сорта. Опора шарнирная. Нормативная нагрузка; суммарную нагрузку от собственного веса балки, собственного веса покрытия, снеговой нагрузки qн = 11,5 кН/м.

208 Определяем расчетные сопротивления древесины балки, работающей на изгиб.

σс(τ), МПа 26

24 1 2

14 0 30 60 90 120 τ, мин.

Рисунок 1. Зависимость напряжения сжатия (σс(τ)) от времени горения τ деревянной стойки: 1 - необработанная древесина, 2 - обработанная

Согласно нормативам для сосны второго сорта имеем: - расчетное сопротивление на изгиб Rв = 26 МПа; - расчетное сопротивление на скалывание вдоль волокон древесины Rск = 3,2 МПа. Определяем значение изгибающего момента М в сечении балки, наиболее опасного с нормальным напряжением. Определяем положение наиболее опасное по нормальным напряжениям расчетного сечения:

l ⋅ hоп x = = 07,3 м. (10) 2 ⋅ hc Определяем высоту балки в расчетном сечении: 2(h − h )⋅ x h = h + c оп = 95,0 м. (11) p оп l Определяем изгибающий момент в расчетном опасном сечении: q ⋅ (lx − x) M = н = 122 кН·м. (12) x 2 Определяем значение максимальной силы на опоре балки: ⋅lq Q = = 5,57 кН. (13) 2 Для элементов прямоугольного сечения значение σск(τ) можно определить по выражению:

5,1 ⋅Qн σ ск ()τ = . (14) Fb ()τ Определяем значение изгибающего момента (М) в сечении балки, наиболее опасного с нормальным напряжением. Определяем для избранных моментов времени размеры рабочего сечения балки h(τ) и b(τ) с учетом скорости обугливания древесины; момент

209 сопротивления W(τ) расчетного сечения балки; соответствующие напряжения изгиба σв(τ) в расчетном сечении (рис. 2).

σв(τ), МПа 27

1 18

0 0 100 200 300 400 τ, мин.

Рисунок 2. Зависимость напряжения изгиба (σв(τ)) от времени обугливания τ деревянной балки: 1 - необработанная древесина, 2 – обработанная

Определяем напряжения скалывания σск(τ) в опорном сечении балки в избранные моменты времени с учетом уменьшения рабочего сечения балки за счет обугливания (рис. 3).

σск(τ), МПа

1 2

0 0 100 200 300 400 τ, мин.

Рисунок 3. Зависимость напряжения скалывания (σв(τ)) от времени обугливания τ деревянной балки: 1 - необработанная древесина, 2 - обработанная

210 Рассмотрение полученных расчетов свидетельствует о том, что при обугливании исчерпания прочности балки на изгиб происходит раньше, чем исчерпания прочности балки на скалывание. Поэтому определение границы устойчивости от обугливания балки необходимо проводить по потере прочности на изгиб. Определенное время после начала разрушения древесины балки к потере балкой своей несущей способности от усилий изгиба на опоре балки от изгибающего момента (М) составляет больше 120 мин.

ВЫВОДЫ Таким образом, обработка древесины органо-минеральным покрытием снижает скорость обугливания рабочего сечения и увеличивает огнестойкость деревянных конструкций более чем в три раза.

REFERENCES 1.Цапко Ю.В., 2013: Влияние поверхностной обработки древесины на огнестойкость деревянных конструкций. Восточно-Европейский журнал передовых технологий, Вып. 5/5 (65); 11–14. 2. Романенков И.Г., 1991: Огнезащита строительных конструкций. Стройиздат. Москва; 320. 3.Молчадский И. С.,2005: Пожар в помещении. ФГУ ВНИИПО, Москва; 456. 4.Gusiy S., Yurii Tsapko, 2013: The study of some aspects of the impact on the stability of wood protection wood structures. “1st International Conference on the Chemistry of Construction Material by the GDCh Division of Chemistry of Construction Chemicals October 7-9, Berlin; 209-212. 5. Guzii, Yurii Tsapko, A. Kravchenko, M. Remenets, 2016: Fire Protection of wooden storage containers for explosive and pyrotechnic products. // Eurika: Physics Sciences and Engineering, Number 2; 34-42.

REFERENCES 1.Tsapko Ju.V., 2013: Vlijanie poverhnostnoj obrabotki drevesiny na ognestojkost' derevjannyh konstrukcij. Eastern-European journal of enterprise technologies, 5/5 (65), 11– 14. 2.Romanenkov I.G., 1991: Ognezashhita stroitel'nyh konstrukcij. Moscow, Russia, Strojizdat; 320. 3.Molchadskij I.S., 2005: Pozhar v pomeshhenii. Moscow, Russia, FGU VNIIPO, 456. 4.Gusiy S., Yurii Tsapko, 2013: The study of some aspects of the impact on the stability of wood protection wood structures. “1st International Conference on the Chemistry of Construction Material by the GDCh Division of Chemistry of Construction Chemicals. Berlin; 209-212. 5.S. Guzii, Yurii Tsapko, A. Kravchenko, M. Remenets, 2016: Fire Protection of wooden storage containers for explosive and pyrotechnic products. // Eurika: Physics Sciences and Engineering, Number 2; 34-42.

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Streszczenie: Wpływ substancji organo-mineralnych na zabezpieczenie ogniowe drewna. . Praca opisuje wpływ zabezpieczeń na prędkość i głębokość zwęglenia drewna narażonego na ogień.

Corresponding author:

Tsapko Aleksey Department of Wood Processing National University of Life and Environmental Sciences of Ukraine, Kyiv, vul. Geroiv Oborony 15, 03041, Ukraine email: [email protected] phone: +380678474027

212 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 213-219 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Вычисление изменения температуры воздуха во фризере во время замораживания тополиных кряжей

НАТАЛИЯ ТУМБАРКОВА1, НЕНЧО ДЕЛИЙСКИ1, ЛАДИСЛАВ ДЗУРЕНДА2, ИЗАБЕЛА РАДКОВА1

1Факультет лесной промышленности, Лесотехнический университет, София, Болгария 2Факультет наук и технологии древесины, Техннический университет в Зволене, Словакия

Abstract: Equations for the computation of the experimentally determined change in the processing air medium temperature Tm in freezer during freezing of logs have been suggested. The decreasing of Tm during the freezing of the logs is approximated by exponential equations, which after determined processing time go into linear equations. The values of the variables in the suggested equations have been determined in the work for the case о о of the change in Tm from about 25 С to about –30 С during separatly 50 h freezing in freezer of two poplar logs with diameter of 240 mm and length of 480 mm. The suggested equations are necessary for participation in the boundary conditions of mathematical models, which describe the logs’ freezing process at concrete values of the processing air medium’s parameters.

Keywords: mathematical description, processing air medium, poplar log, freezing, defrosting

ВВЕДЕНИЕ При разнообразных технологических и инженерных расчетах приходится определять степень льдистости деревянных сортиментов в зависимости от температуры воздействующей на них воздушной среды и от продолжительности этого воздействия. Такие расчеты можно производить при помощи математических моделей, которые адекватно описывают весьма сложный процесс замерзания гигроскопически связанной и свободной воды в древесине. В граничных условиях таких моделей участвует температура обрабатывающей (воздействующей на сортименты) воздушной среды Tm [2, 3, 7, 8]. Поэтому, для решения таких моделей необходимо включить в них достаточно точное математическое описание Tm. Целью настоящей работы является составление уравнений, которые аппроксимируют изменение температуры обрабатывающей воздушной среды Tm во фризере во время замораживания в нем деревянных сортиментов, а также использование этих уравнений для вычисления экспериментально установленного изменения Tm для случаев многочасового замораживания во фризере тополиных кряжей с конкретными параметрами.

МЕХАНИЗМ РАСПРОСТРАНЕНИЯ ТЕПЛА В КРЯЖАХ ВО ВРЕМЯ ИХ ЗАМОРАЖИВАНИЯ Во время охлаждения кряжей с целью их замораживания кроме чисто тепловых процессов осуществляется обмен влагой между обрабатывающей средой и кряжами. Известно, что величина коэффициента влагопроводности древесины в сотни раз меньше ее коэффициента температуропроводности [1, 4, 5, 7]. Благодаря этому во время замораживания древесины происходит незначительное изменение ее влажности по сравнению с изменением ее температуры. Этот факт позволяет пренебречь обменом влажности между обрабатывающей средой и кряжами и изменение температуры в них

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во время замораживания рассматривать как результат обмена только теплом между ними, а также принять, что распространение тепла в кряжах происходит единственно путем теплопроводности. Поэтому механизм распространения тепла в подвергнутых замораживанию кряжах можно описать математически при помощи уравнения теплопроводности. В цилиндрических координатах при переменных значениях теплофизических характеристик древесины его можно представить следующим образом в одномерном (1D) варианте, описывающем разпространение тепла только по радиусу подвергнутых замораживанию кряжей [2, 3, 6]:

2 ∂ rT τ),(  ∂2 rT τ),( 1 ∂ rT τ),(  λ∂ T u),(  ∂ rT τ),(  c T u ρ u)(),( λ= T u),(  +  + r + q (1) e r  2    v τ∂  ∂r r ∂r  ∂T  ∂r 

с началным условием

(rT 0, ) = T0 (2)

и граничным условием, описывающим конвективное тепловое взаимодействие между цилиндрической поверхностью кряжей и окружающей воздушной средой:

∂T τ),0( αr τ),0( −= []T τ),0( − Tm τ)( , (3) ∂r λr τ),0(

где се – эффективная удельная теплоемкость древесины, учитывющая отсутствие или наличие льда в соответствующих точках объема кряжей во время их замораживания, -1 -1 J.kg .K ; λr, λr(0,τ) – коэффициент теплопроводности древесины в радиальном направлении соответственно внутри кряжей и на их поверхности во время -1 -1 -3 замораживания, W.m .K ; ρ – плотность древесины, kg.m ; qv – внутренный объемный источник тепла, отражающий выделение латентного тепла воды в древесине во время -3 ее кристаллизации при замерзании, W.m ; αr(0,τ) – коэффициент теплопередачи в радиальном направлении между поверхностью кряжей и окружающей воздушной средой во время замораживания, W.m-2.K-1; r – радиальная координата, с которой решается математическая модель: 0 ≤ r ≤ R, m; R – радиус подвергнутых замораживанию кряжей, m; T – температура, K; T0 – начальная температура кряжей перед их замораживанием, K; T(0,τ) – температура поверхности кряжей во время их замораживания, K; Tm-fr, Tm-dfr – температура воздушной среды вблизи кряжей во время их замораживания, K; τ – время, s.

МАТЕМАТИЧЕСКОЕ ОПИСАНИЕ ТЕМПЕРАТУPЫ Тm Для компьютерного решения математической модели (1) ÷ (3) необходимо располагать математическим описанием участвующей в уравнении (3) температуры воздействующей на кряжи воздушной среды Tm. При экспериментальном исследовании процесса замораживания кряжей во фризере нами установлено, что Tm изменяется по сложной криволинейной зависимости во времени. Эта зависимость с достаточной для расчетов точностью может быть представлена посредством переходящих одну в другую экспоненциальной кривой и прямой линией (см. рис. 1). Экспоненциальное понижение Tm в начале процесса замораживания кряжей может быть описано математически при помощи следующего экспоненциального уравнения:

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exp asympt asympt  τ  exp T = T + T − T exp−  @ 0 τ≤τ≤ , (4) m me ()m0 me   e  τexp  asympt где Tm0 – начальное значение Tm, K; Tme – асимптотическое значение Tm в конце ее lin экспоненциального понижения, K; Tmе – конечное (последнее) значение линейного понижения Tm, K; τ – текущее значение времени процесса замораживания кряжей, s; exp exp τexp – постоянная времени экспоненты Tm = f τ)( , s; τe – текущее время в конце экспоненциального понижения Tm, s; @ – при выполнении условия.

Рис. 1. Изменение на Tm-fr и Tm-dfr во время замораживания кряжей во фризере

exp Линейное понижение Tm после истечения времени τe (рис. 1) можно представить при помощи следующего уравнения:

lin exp exp Tm = a − b( τ−τ e ) @ τe τ≤τ< fr , (5)

где

exp a = Tme , (6)

exp lin Tme −Tme b = , (7) exp τfr τ− e

exp lin Переменные Tmе и Tmе в уравнении (7) означают соответственно конечные значения Tm при их экспоненциальном и при линейном изменениях в процесе замораживания кряжей (см. рис. 1), K. Для обеспечения наилучшего соответствия между експериментально установленными и вычисленными по уравнениям (4) ÷ (7) значениями Tm они должны быть сопоставлены друг с другом. В качестве критерия наилучшего соответствия между сравниваемыми значениями Tm можно использовать минимальное значение min σn−1 среднеквадратической ошибки, вычисляемой по уравнению:

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N calc experim 2 ∑ ()Tn − Tn σ = n=1 , (8) n−1 N −1

calc experim где посредством Tn и Tn обозначены соответственно вычисленные и экспериментально установленные значения Tm, а n – это очередной номер моментов просеса замораживания данного кряжа, в которых производится сравнение между ними: 0 ≤ n ≤ N.

ВЫЧИСЛЕНИЕ ПЕРЕМЕННЫХ В УРАВНЕНИЯХ ДЛЯ ОПРЕДЕЛЕНИЯ Tm Для вычисления переменных в приведенном выше описании Tm, а также для min вычисления минимального значения среднеквадратической ошибки σn−1 , нами составлена компьютерная программа в вычислительной среде MS Excel 2010. При помощи компьютерной программы определены значения переменных в уравнениях (4) ÷ (7) по отношению к експериментально установленному изменению Tm во время замораживания в горизонтальном фризере тополиных кряжей с диаметром 0.24 m и длиной 0.48 m. Автоматическое измерение и запись данных понижения температуры Tm во время экспериментов осуществлялось с заданным интервалом через 15 min при помощи Data Logger-а типа HygrologNT швейцарской фирмы ROTRONIC. Продолжительность процесса замораживания каждого из кряжей составляла 50 h. Это означает, что количество экспериментальных точек N в уравнении (8) для каждого кряжа равнялось 200. В таблице 1 приведены вычисленные при помощи экселовской программы значения переменных, которые участвуют в уравнениях (4) ÷ (7) для случаев поотдельного замораживания двух тополиных кряжей, обозначенных ниже как Кряж Т1 и Кряж Т2. В соответствии с приведенными в этой таблице значениями переменных, уравнения (5) и (7) получают следующий вид:

• Для замораживания кряжа Т1:

exp  τ  Tm = 257 99. + 83.37 exp−  @ 0 ≤τ≤ 28800s , (9)  5400 

lin −5 Tm = 258 17. − 73.9 ⋅10 ( −τ 28800) @ 28800s ≤τ< 180000s , (10)

• Для замораживания кряжа Т2:

exp  τ  Tm = 257 35. + 61.40 exp−  @ 0 ≤τ≤ 28800s , (11)  5220  lin −5 Tm = 257 52. − 89.7 ⋅10 ( −τ 28800) @ 28800s ≤τ< 180000s . (12)

На рис. 2 показано экспериментально установленное и вычисленное по уравнениям (9), (10), (11) и (12) изменение Tm во время замораживания кряжей Т1 и Т2. На рисунках видна весьма хорошая точность аппроксимации экспериментальных значений Tm при помощи этих уравнений. Об этом свидетельствуют небольшие min значения среднеквадратического отклонения σn−1 , которые для обоих кряжей находятся в пределах 1.35 K для экспоненциальных и 0.65 K для линейных аппроксимирующих уравнений.

216

Таблица 1. Значения переменных в уравнениях (9) ÷ (12) при замораживании во фризере тополиных кряжей с диаметром 0.24 m и длиной 0.48 m

Еди- Значение переменных Обозна- № Наименование переменных ница чение Кряж Т1 Кряж Т2 СИ Переменные экспоненциального понижения Тm в процессе замораживания кряжей Измеренное значение Т в начале 295.82 297.96 1. m T K процесса замораживания кряжей m0 (22.67 oC) (24.81 oC) Экспериментальное асимптотическое 257.99 257.35 2. значение Т , к которому стремится Т T asympt K m m fr-me (–15.16 oC) (–15.80 oC) при ее экспоненциальном понижении Постоянная времени 3. экспоненциального понижения Тm в τexp s 5 400 5 220 процессе замораживания Текущее время в конце 28 800 28 800 4. экспоненциального понижения Т в τexp s m fr-e (8.0 h) (8.0 h) процессе замораживания кряжей Вычисленное по уравнению (9) exp 258.17 257.52 5. значение Тm в конце ее 8 h экспоненц. T K me (–14.98 оС) (–15.63 оС) понижения Минимальное среднеквадратическое min 6. отклонение Тm во время ее σn−1 K 1.35 1.23 экспон.пониж. Переменные линейното понижения Тm в процессе замораживания кряжей Начальное значение Т при ее m 258.17 257.52 7. линейном понижении в процессе a = T exp K fr me (–14.98 оС) (–15.63 оС) замораживания Коэффициент наклона линейного -1 -5 -5 8. понижения Тm в процессе bfr K·s 9.73·10 7.89·10 замораживания Текущее время в конце линейного lin 180 000 180 000 9. понижения Тm в процессе τ s e (50 h) (50 h) замораживания Вычисленное по уравнению (10) lin 243.46 245.59 10. значение Тm в конце ее линейного K Tme (–29.69 оС) –27.56 оС понижения Минимальное среднеквадратическое min 11. отклонение Тm во время ее линейного σn−1 K 0.65 0.42 понижения

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25 20 эксперимент 15 вычислено

C 10 o , , 5 m t 0 -5 -10 -15

Температура -20 -25 -30 -35 0 5 10 15 20 25 30 35 40 45 50 Время τ, h

25 20 эксперимент 15 вычислено

C 10 o , , 5 m t 0 -5 -10 -15

Температура -20 -25 -30 -35 0 5 10 15 20 25 30 35 40 45 50 Время τ, h

Рис. 2. Изменение tm во время 50 h замораживания во фризере кряжей Т1 (слева) и Т2 (справа) ЗАКЛЮЧЕНИЕ В данной работе предложены уравнения для аппроксимации экспериментально установленного изменения температуры воздушной обрабатывающей среды Tm во время замораживания во фризере деревянных сортиментов. Понижение Tm во время замораживания сортиментов представлено при помощи экспоненциальных уравнений, которые после определенной продолжительности процесса переходят в линейные уравнения. Составлена компьютерная программа на MS Excel 2010 для определения значений переменных, участвующих в предложенных уравнениях на основе обработки экспериментально установленного изменения Tm во время замораживания. В качестве критерия наилучшего соответствия вычисленных по уравнениям и соответствующих им экспериментальным значениям Tm использовано минимальное значение min среднеквадратического отклонения σn−1 . При помощи компьютерной программы определены значения переменных, участвующих в предложенных уравнениях для случаев понижения Tm в диапазоне от 20 оС до –30 оС во время поотдельного 50 h замораживания тополиных кряжей с диаметром 0.24 m и длиной 0.48 m. Предложенные уравнения необходимы для их участия в граничных условиях математической модели, описывающей процессы замораживания кряжей при конкретных значениях параметров обрабатъвающей воздушной среды.

ЛИТЕРАТУРА 1. ВИДЕЛОВ, Х., 2003: Сушене и топлинно обработване на дървесината. ЛТУ, София.

218

2. ДЕЛИЙСКИ, Н., 1979: Математично моделиране на процеса на нагряване чрез топлопроводност на цилиндрични дървени сортименти. Научни трудове на ВЛТИ, серия МТД, т. XXV, С., Земиздат: 21-26. 3. ДЕЛИЙСКИ, Н., ДЗУРЕНДА, Л., 2010: Моделирование тепловых процессов в технологиях обработки древесины. ТУ-Зволен, Словакия. 4. ШУБИН, Г. С., 1990: Сушка и тепловая обработка древесины, Лесная промышленность, Москва. 5. ЧУДИНОВ, Б. С., 1968: Теория тепловой обработки древесины. Наука, Москва. 6. DELIISKI, N., 2013: Modelling of the energy needed for heating of capillary porous bodies in frozen and non-frozen states. ISBN 978-3-639-70036-7, Lambert Academic Publishing, Scholars’ Press, Saarbrücken, Germany, 116 p., http://www.scholars- press.com//system/ covergenerator/build/ 1060 7. ŁAWNICZAK, M., 1995: Zarys hydrotermicznej i plastycznej obróbki drewna. Czesć I. Warzenie i parzenie drewna. Poznañ. 8. STEINHAGEN, H. P., 1991: Heat transfer computation for a long, frozen log heated in agitated water or steam - a practical recipe. Holz als Roh- und Werkstoff, № 7-8.

Streszczenie: Zaproponowano równania określające zmierzoną eksperymentalnie zmianę temperatury powietrza Tm w zamrażarce podczas zamrażania kłód. Obniżanie temperatury medium jest aproksymowane równaniami wykładniczymi, zmieniającymi się w liniowe po ustaniu procesu. Zaproponowane równania są niezbędne do określenia warunków brzegowych modelu matematycznego opisującego procez zamrażania kłód w powietrzcu jako medium chłodzącym.

Corresponding authors:

Natalia Tumbarkova, Nencho Deliiski, Izabela Radkova Faculty of Forest Industry, University of Forestry, Kliment Ohridski Bld. 10, 1796 Sofia, BULGARIA, e-mails: [email protected], [email protected], [email protected]

Ladislav Dzurenda, Faculty of Wood Sciences and Technology, Technical University of Zvolen, T. G. Masaryk 24, 96053, Zvolen, SLOVAKIA, e-mail: [email protected]

219 Annals of Warsaw University of Life Sciences – SGGW Forestry and Wood Technology № 96, 2016: 220-225 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Изменения прочностных свойств гравировой кожи ANNA VILHANOVÁ, MARCELA CIESLAROVÁ

Departement of Furniture and Wood Products, Technical University in Zvolen

Аннотация: Целью работы создание подходящей степени гравировки кожи различной плотности на базе глубины выгорания и определения влияния различных степеней гравировки на крепкость кожи. Для эксперимента были отобраны образцы для испытаний бычьной кожи задней части, которые используются для покрытия наиболее нагруженных части мягкой мебели. Техника гравировки была применена помощью ЦO2 лазерa в четырех этапах. Индивидуальные уровни гравировки были разные интенсивностью и скоростью лазерного лучa. Глубинa прогара была измерена с помощью микрометра.

Κлючевые слова: гравировкa кожи, ЦO2 лазер, глубинa прогара ВВЕДЕНИЕ Лазерная гравировка технология, которую можно считать в качестве замены ручной гравировки. Через него можно создавать различные надписи, логотипы и орнаменты. Наиболее часто используемый тип лазера ЦО2-лазер. Технология лазерной гравировки может быть использована на гибкие материалы, например текстиль, кожа для жестких материалов, например. дерева или металла [Belli et al. 2005, Ondogan et al. 2005]. Лазерные устройства в области текстиля и кожи используется с 19-го века, и там широко популярны. Их основными преимуществами являются точность, эффективность, диапазон автоматизации [Kan et al. 2014, Lu et al. 2010, Sutcliffe et al. 2000, Kovacs et al. 2006]. Лазерное излучение обладает уникальными характеристиками - высокий степень монохроматичести, когерентности, низкая расходимость и способность фoкулачие в небольшое пятно. Гравировка или резка вяэкой пучей излучения представляет собой процесс многопараметрический. Параметры, влияющие на процесс резания или гравировки вяэкой пучей могут быть разделены на три группы,: - свойства вяэкой пучей - свойства характеристик лазерного устройства и процесса резания, гравировки, - характеристики заготовки [Barnekov et al. 1986]. Геометрия режущего разрывa зависит от многих факторов, связанных с процессом резки вяэкой пучей. Его ширина связана с диаметром вяэкой пучей , скоростью подачи луча, использование вспомогательного газа и свойств материала заготовки. Ширина режущего разрыва при резке, а также при гравировке определяет скорость резки, с его еувеличением ширина разрыва уменьшается. Увеличение мощности вяэки пучей при постоянной скорости также приводит к увеличению ширины режущего разрывa. Глубина разреза зависит главным образом от производительности вяэки пучей, скорости резания, типа и давления вспомогательного газа. С увеличением производительности и уменьшительнoй скоростю резки увеличивается глубина разрывa (Gajtanska, 2015). Резка или гравировка кожи возможно, в зависимости от доминирующих процессом декомпозиции материала, рассматриваться как резка химической деградацией материала.

220 ЭКСПЕРИМЕНТАЛЬНАЯ ЧАСТЬ Для гравировки были выбраны четыре типа кожи различной плотности и различной отделки поверхности. Образцы кожи использованы в эксперименте исходили из бычьих шкурей европейского происхождения. Были сделаны хромовыми солями и окрашиваные анилиновыми красками. Плотность кожи была определена в соответствии с соотношением:

= м В [кг.м−3] (1) где: м = вес образцa В = объем образцa

В = л × б × х [м3] (2) где: л = длина образцa б = ширина образцa х = толщина образцa Выбранные типы кожи были подвергнуты четырем степеням гравировки. На различных этапах гравировки были разные мощности и скорости. Как было упомянуто выше, для достижения желаемых свойств режущего разрывa при обработке материала ЦО2 лазером необходимо для конкретного материала выбрать правильную скорость и мощность лазерного устройства.

Рисунок 1 - Гравировка ЦО2 лазером

Таблица 1 - Характеристики выбранных степеней гравировки Мощность лазера Скорость лазерa Степень гравировки [W] [м/c] I. 40 20 II. 43 20 III. 46 20 IV. 43 30

Глубина перегораниa была измерена для гравированного рисунка с использованием цифровово толщиномера.

221 Прочность кожи была определена в соответствии с соотношением:

Φ σ = []MPa (3) ΤΑΓΑ C где: Ф = максимальная сила при разрыве образца, C = начальная площадь поперечного сечения рабочей части испытуемого образца,

РЕЗУЛЬТАТЫ И ОЦЕНКА Целью эксперимента было определить влияние выбранных факторов, в нашем случае плотность кожи, мощность лазера и скорость лазера на глубину разрывa суставов в нашем случае это глубина гравировки. В таблице 2 приведены значения глубины перегораниa кожи различной плотности, которые подверглись лазерной гравировкe CO2 в одиночных оговоренных ступенях гравировки. Таблица 2 – Глубина перегораниa на различных этапах гравировки Плотность Глубина перегораниa Тип кожи кожи [мм] [кг/м3] I. степень II. степень III. степень IV. степень сливочная 601 0,18 0,7 1,34 0,38 светло- 634 0,2 0,6 0,9 0,4 коричневая белая 690 0,12 0,61 1,34 0,38 темно- 678 0,24 0,6 0,96 0,41 коричневая

На рисунке 2 графически показаны различия глубину перегораниа в различных стадиях гравировки. Из результатов можно констатировать, что наибольшая глубина перегораниa была достигнута в 3. стадии гравировки, где мощность лазера был 46 W и скорость былa 20 м/c.

222 1.6

1.4

1.2

1 сливочная

] 0.8 светло-коричневая мм [ белая 0.6 темно-коричневая 0.4 Глубина перегораниa перегораниa Глубина 0.2

0 I. степень II. степень III. степень IV. степень

Рисунок 2 - Глубина выгорания кожи на различных этапах гравировки При материалах обрабатываных гравировкой важнее, кроме характеристик гравировки, наблюдать изменение прочностных свойств выгравированного материала. Таблица 3 показывает зависимость предела прочности при растяжении дублёной кожи подвергнутой гравировке в различных степенях. Таблица 3 - Прочность для кожи гравировки на различных этапах гравировки Прочность Прочность кожи после гравировки кожи перед [MПa] Тип кожи гравировкой I. степень II. степень III. степень IV. степень [MПa] сливочная 19 17 12 8 13 светло- 12 12 11 10 11 коричневая белая 17 13 15 9 17 темно- 15 12 8 10 11 коричневая

На рисунке 3 графически показано изменение прочности из-за отдельных видов кожи влиянием гравировки в различных степенях. Из этих значений можно констатировать, что наибольшая потеря прочности наступилa, при гравировке в степени III, где она была избрана самая высокая мощность лазера.

223 70

40 темно-коричневая белая 30 светло-коричневая 20 сливочная Прочность кожи [MПa] 10

0 I. II. III. IV. степень степень степень степень

Рисунок 3 - Изменения прочности кожани воздействием гравировки ЗАКЛЮЧЕНИЕ Иэ результатов эксперимента можно костатировать, что для обивочной кожи используемой в производстве мягкой мебели лучше использовать при гравировке высшую скорость лазерного луча и более низкую мощность. Этот вывод был продемонстрирован при сравнении второй и четвертой степени гравировки, где была избрана одинаковая производительность, но на четвертой степени была выбрана более высокая скорость и снижение прочности влиянием гравюровки было ниже, чем на второй степени

СПИСОК ЛИТЕРАТУРЫ:

1 BELLI, R., MIOTELLO, A., MOSANER, P., TONIUTTI, L. 2005: Laser cleaning of ancient textiles. Applied Surface Science, 247, s. 369–372. 2 ONDOGAN, Z., PAMUK, O., ONDOGAN, E. N., OZGUNEY, A. 2005: Improving the appearance of all textile products from clothing to home textile using laser technology. Optics and Laser Technology, 37, s. 631–637. 3 KAN, C.W. 2014: CO2 laser treatment as a clean process for treating denim fabric. Journal of Cleaner Production, 66, s. 624–631. 4 LU, J.M., WANG, M.J. J., CHEN, C.W., WU, J.H. 2010: The development of an intelligent system for customized clothing making. Expert Systems with Applications, 37, s. 799–803. 5 SUTCLIFFE, H., COOPER, M., FARNSWORTH, J. 2000: An initial investigation into the cleaning of new and naturally aged cotton textiles using laser radiation. Journal of Cultural Heritage, 1, s. 241–S246. 6 KOVACS, L., ZIMMERMANN, A., BROCKMANN, G., GÜHRING, M., BAURECHT, H., Papadopulos, N., et al. 2006: Three-dimensional recording of the human face with a 3D laser scanner. Journal of Plastic, Reconstructive and Aesthetic Surgery, 59, s. 1193– 1202. 7 BARNEKOV, V.,G. MCMILLIN, W.,CH. HUBER, H.,A. 1989: Laser machning wood composites. In: Forest Products Journal, ISSN 0015-7473, vol. 39, s. 76-78

224 8 GAJTANSKA, M. SUJA, J. IGAZ, R. KRIŠŤÁK, Ľ. RUŽIAK, I. 2015: Rezanie smrekového dreva CO2 laserom. TU vo Zvolene, ISBN 978-80-228-2837-6, 82 s.

Streszczenie. Zmiana właściwości wytrzymałościowych skóry grawerowanej. Celem pracy było uzyskanie właściwego stopnia grawerowania skóry o różnych gęstościach bazując na głębokości wypalania i ustalenie wpływu różnych stopni grawerowania na wytrzymałość skóry. Do badań zostały przygotowane próbki ze skóry wołowej, która jest wykorzystywana do tapicerowania najbardziej intensywnie obciążonych części mebli. Zostało zastosowane czteroetapowe grawerowanie laserem CO2 . Poszczególne stopnie grawerowania były uzyskane po przez stosowanie różnych intensywności i szybkości promieni laserowych. Głębokość wypalania została zmierzona mikrometrem.

225 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 226-229 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The gross calorific value and the net calorific value of selected exotic wood species

BOGUSŁAWA WALISZEWSKA, MICHAŁ DUDA, HANNA WALISZEWSKA, AGNIESZKA SPEK-DŹWIGAŁA, AGNIESZKA SIERADZKA

Institute of Chemical Wood Technology, Faculty of Wood Technology, Poznań University of Life Science

Abstract: The gross calorific value and the net calorific value of selected exotic wood species. In the study, the gross calorific value and the net calorific value of selected exotic species present on the Polish market were determined. The gross calorific value and the net calorific value of exotic wood were quite high and comparable with those of native species recognized as species of high calorific value which are used for fuel.

Keywords: exotic wood, heating value,

INTRODUCTION Wood as a renewable raw material is used in many industries. Despite the development of technology, wood compared with other raw materials has not lost its significance, and is even becoming a more and more valuable material. In Poland, mainly native species are used due to their prevalence. However, in the past few years exotic species have become more and more popular. According to the International Union of Forest Research Organizations (IUFRO), there is a commercial interest in about 140 species (Kozakiewicz 2004). Growth conditions of trees from tropical climate differ from those from the temperate climate. The specificity of climate affects the different qualities of wood, including, among others, dyeing. More and more often Polish manufacturers offer floor panels, panelling, furniture made from exotic wood with a beautiful colour and drawing, construction woodwork and other (Kozakiewicz 2006). In addition, exotic wood due to its properties different from those of native species, is used for the production of artistic goods: jewellery, ornaments, toys and musical instruments. Since the dawn of history, wood has served men as fuel and currently remains an important source of energy for some local groups of recipients. As a raw material created during the photosynthesis process, wood contains a small amount of non-combustible substances, and during its combustion several times less pollution is released to the atmosphere than while coal combustion. It is an ecological fuel, totally renewable, and the use of its energy is environmentally and climate friendly. The use of recovered wood for energy purposes is also a significant environmental aspect. Thermal treatment of waste coming from the wood industry, apart from the possibility of obtaining energy, contributes to: - improvement of the environment condition; - saving landfill space; - reduction of the amount of carbon dioxide in the atmosphere by replacing fossil fuels; - reduction of fire hazard at landfills; - decomposition of numerous harmful substances (Ratajczak et al., 2003).

226

MATERIALS AND METHODS The study was conducted on four exotic wood species: doussie (Afzelia africana), merbau (Intsia sp.), padouk (Pterocarpus soyauxii Toub.) and wenge (Millettia Laurentii De Wild.). Heartwood separated from lumber underwent size reduction into small pieces using a circular saw and was next grounded by means of a PULVERISETTE 15 laboratory knife mill. Analytical fraction, i.e. dust <0.1 mm was separated by sieving. Determination of gross calorific value was performed by means of a KL-12MN calorimeter according to PN-81/G-04513, which is designed to measure the gross calorific value of solid fuels. For the purpose of the analysis, wood material was prepared in the form of compressed tablets. The analysis consisted of the measurement of complete combustion of the sample in an oxygen atmosphere placed in a combustion bomb which was immersed in water and the measurement of the temperature rise of the water. The values were calculated according to the formula:

C(D − k) − c kJ Q a = t [ ] s m kg where: J C - heat capacity of the calorimeter of 12 783.69 [ ] o C o Dt –temperature rise of the main period [ C] k – correction for heat exchange with the surrounding [°C] c - sum of corrections for additional thermal effects [J] m –mass of the sample of the fuel

For a more complete characterization of the analyzed raw material, also its net calorific a value Qi that is the gross calorific value decreased by the heat of vaporization of water separated from the fuel during combustion was determined. These values were calculated according to the following formula:

kJ Q a = Q a – 24,42(Wa – 8,94Ha) [ ] i s kg where:

a J Q s - average gross calorific value of solid fuel in the analytical state [ ] g J 24.42 –heat of vaporization of water at 25 °C corresponding to 1% of water in the fuel [ ] g Wa –moisture content in the analytical sample of fuel [%] 8.94 –analytical factor for conversion of hydrogen content into water content Ha –hydrogen content in the analytical sample of fuel, where Ha = 6.5%.

227

RESULTS

Fig . 1. Gross calorific value of analyzed exotic wood species

The results of gross calorific value measurements for the tested exotic trees species are shown in Fig. 1. The values ranged from 20 770 kJ/kg to 22 530 kJ/kg. The highest gross calorific value was observed for padouk heartwood and the lowest for merbau wood species. The other two analyzed exotic species, i.e., wenge and merbau, had similar values at the level of 21 140 and 20 990 kJ/kg respectively. Analyzing the obtained results it can be concluded that the values for exotic species are high comparing to native species. Stolarski et al. (2013) reported lower values of this parameter for deciduous species: for example the gross calorific value for robinia 19 400 kJ/kg, for poplar 19 930 kJ/kg and for willow 19 890 kJ/kg. Whereas Prosinski (1984) for pine heartwood with density 0.55 g/cm3, and resin content at the level of 8.1%, reported gross calorific value of 21 400 kJ/kg. Therefore, it can be observed that the results obtained from the determination of gross calorific value of exotic wood species are comparable with this parameter for coniferous species characterized by significant resin content.

21500 21060 21000

20500

20000 19260 19630 19460 19500 [kJ/kg] 19000

18500

18000 doussie wenge merbau padouk

Fig . 2. Net calorific value of analyzed exotic wood species

The calculated net calorific values of analyzed exotic wood species are shown in Fig. 2. This is the gross calorific value taking into account the heat of vaporization of water separated

228 from the sample during combustion. The highest net calorific value of 21060 kJ/kg was reported for padouk heartwood, and the lowest, 19 260 kJ/kg for doussie wood. Similar to gross calorific value results, when comparing the net calorific values, one can notice that wenge and merbau wood showed similar value of this parameter which amounted to 19 630 and 19 460 kJ/kg respectively. Similar values for wood of deciduous species are reported by Prosiński (1984), i.e. for a completely dry birch wood - 19 620 kJ/kg, for alder - 19 780 kJ/kg, and for oak - 20 330 kJ/kg.

It can be concluded that the studied exotic wood species had relatively high gross calorific values and net calorific values and that the values of these parameters were comparable with those of resinous species or deciduous species considered as species of high calorific value growing in temperate climate.

REFERENCES 1. KOZAKIEWICZ P., 2004: Drewno egzotyczne – od pochodzenia po wykorzystanie. Przemysł drzewny, styczeń 2004: 25-30. 2. KOZAKIEWICZ P., 2006: Merbau – drewno egzotyczne z Azji i Oceanii. Przemysł drzewny, wrzesień 2006: 21-24. 3. PROSIŃSKI S., 1984: Chemia drewna. PWRiL. 4. RATAJCZAK E., SZOSTAK A., BIDZIŃSKA G., 2003: Drewno poużytkowe w Polsce. Wyd. ITD., Poznań: 97. 5. STOLARSKI M., KRZYŻANIAK M., WALISZEWSKA B., SZCZUKOWSKI S., TWORKOWSKI J., ZBOROWSKA M., 2013: Lignocellulosic biomass derived from agricultural land as industrial and energy feedstock. Drewno. Pr. Nauk. Donies. Komunik. 2013, vol. 56, nr 189.

Streszczenie: Ciepło spalania i wartość opałowa wybranych gatunków drewna egzotycznego. W pracy zbadano ciepło spalania i wartość opałową wybranych gatunków drewna egzotycznego: doussie, merbau, wenge i padouka spotykanych na rynku polskim. Badane parametry były dość wysokie i porównywalne z gatunkami rodzimymi uznawanymi jako wysokokaloryczne i stosowanymi na opał. Największą wartością (22 530 kJ/kg) ciepła spalania charakteryzowało się twardzielowe drewno padouka.

Corresponding author:

Bogusława Waliszewska Institute of Chemical Wood Technology, Faculty of Wood Technology, Poznań University of Life Sciences ul.Wojska Polskiego 38/42, 60-637 Poznań, Poland email: [email protected] phone: +48 61 848 74 65

229 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 230-236 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Thermal modification of lignocellulosic particles to obtain a solid biofuels with improved properties

MAŁGORZATA WALKOWIAK, MAGDALENA WITCZAK, WOJCIECH J. CICHY Environmental Protection and Wood Chemistry Department, Wood Technology Institute – ITD, Poznań RYSZARD KANIEWSKI Laboratory of Chemical Evaluation and Processing of Fibre Raw Materials, Institute of Natural Fibres & Medicinal Plants – IWNiRZ, Poznań

Abstract: Thermal modification of lignocellulosic particles to obtain a solid biofuels with improved properties. The aim of the study was to investigate the effect of the thermal pretreatment of lignocellulosic raw materials on the properties of solid biofuels. The preliminary studies included mustard straw, hemp straw, grass stalks, tobacco stalks, sunflower hulls, miscanthus straw, rape straw, cereal straw, Virginia mallow straw and rape seeds. Torrefaction was carried out in nitrogen atmosphere at 220°C for 30 minutes. It was specified the weight loss of the torrefied samples. In the raw and torrefied materials the ash content, elemental analysis, calorific value and water absorption were determined. It was found that the thermal treatment of the tested lignocellulosic materials is able to provide solid biofuels with improved properties - better calorific value and hydrophobicity. The obtained results indicate for further research needs, particularly in terms of conditions of the torrefaction process.

Keywords: lignocellulosic materials, biomass, solid biofuels, thermal modification, torrefaction, bioenergy

INTRODUCTION Since the first industrial revolution, acquisition of energy raw materials around the world has been systematically growing. Because of the limited deposits of fossil fuels, renewable energy sources draw increasing attention. Biomass, among the other sources, and its use for energy production, can significantly help reduce greenhouse gas emissions and meet the targets established in Kyoto Protocol. One of the essential problems of energy companies using biofuels to produce heat and electricity is a large diversity of properties of biomass. This situation is related to the origin of biomass (woody biomass, agriculture biomass), conditions of storage (atmospheric conditions) and the period of acquisition. One way to significantly reduce the adverse properties of the biomass as a fuel is its preliminary heat treatment under controlled process conditions. In recent years, torrefaction of lignocellulosic biomass has attracted more interest in research resulting from its potential applications. In order to recognize the role played by torrefaction in improving the properties of biomass, a number of studies have been described, for instance: Bergmann, 2005 [1, 2], Prins et al, 2006 [3], Van der Stelt et al, 2011 [4], Tumuluru et al, 2011 [5], Medic et al, 2012 [6]. Appropriately conducted heat treatment may lead to the homogeneous property of the produced biofuel, especially in a significant reduction in the natural hydrophilic properties of the material. In literature, the heat treatment process is defined as torrefaction, synonyms include: mild or slow pyrolysis, high-temperature drying, roasting, wood cooking and wood browning. The name of torrefaction is adopted from roasting of coffee beans, which is performed at lower temperature while using air. Nevertheless, an important mechanical effect of torrefaction on biomass is supposed to be similar to its effect on coffee bean, which is the resulting brittle structure. In the 1930’s the principles of torrefaction were first reported in relation to woody biomass. Process was carried out on its application to produce a gasifier fuel [1]. Bourgois

230 and Guyonnet in 1980 described the torrefaction wood as efficient biofuel for combustion and gasification [7]. Researchers studied combustion process of torrefied wood and torrefied biomass since 1990’s [8-11]. Torrefaction is a thermochemical process at a temperature of 200-300oC. It is carried out under atmospheric conditions and in absence of oxygen (for example: nitrogen [3]). The efficiency of mass and energy in torrefaction process depends on temperature, time and type of biomass. In addition, the process is characterized by low particle heating rates (<50oC/min) and the time of process oscillates in one hour. During the torrefaction process partial decomposition of biomass with the separation of volatile products occurs. The main product is a solid state, which is often called as torrefied biomass or char. Thermal modification has the favorable effect to increase the calorific value and hydrophobic properties of the biomass. The aim of the study was to investigate the effect of thermal pretreatment of lignocellulosic raw materials to the properties of the solid biofuels. The work is a continuation of previously conducted studies related to the wood torrefaction [12]. Extending of this issue for another kinds of lignocellulosic materials is a new cognitive aspect of this subject.

MATERIALS AND METHODS

The samples were chosen from different lignocellulosic materials: mustard straw, hemp straw, grass stalks (hay), tobacco stalks, sunflower hulls, miskanthus straw, rape straw, cereal straw, Virginia mallow straw, rape seeds and willow. In raw materials as well as torrefied materials the following parameters were determined: moisture, ash, ultimate analysis, gross calorific value, net calorific value and water absorption. Pre-ground material was disintegrated in a knife-mill or impact mill into grains of the desired size. In samples of 1.0 mm grain size, ash content was determined [13]. In samples of <0.2 mm grain sizes, the elementary composition was determined [14] using the elementary analyzer Flash 1112 of Thermo Electron Corporation. The determination was done in three replications, the weighed portions of samples showed 3–4 mg each. For the multi-stage calibration of the instrument, material standards with different content of C, H, N was applied. Furthermore, contents of chlorine and sulphur was determined according to directions in standard EN 15289:2011 [15] using the ion chromatograph ICS-1100 Series of Dionex (column: Dionex IonPacTM AS22, temperature of column: 30°C, conductivity detector, eluent: 4,5 mM Na2CO3/1,4 mM NaHCO3, flow: 1,2 ml/min, volume of sample: 25µl). Gross calorific value was determined according to the standard EN-14918:2010 [16], using the calorimeter KL-12 Mn of Precyzja Bit Company. The calculation of net calorific value was conducted in accordance with the procedure in the mentioned standard [16]. Determination of water absorption (immersion test) was done according to the own procedure based on the method for the determination of water absorption in the torrefied pellets (project SECTOR, 7th Framework Programme). Samples of known moisture content immersed in water during 1h. Then, the samples were filtered by gravity and weighed. The water absorption ratio was expressed as weight percent of mass absorbed water to the mass of dry sample. Torrefaction process was carried out in nitrogen atmosphere at 220°C for 30 minutes with particle heating rates 22°C/min. Samples were conditioned in inert environment for 15 minutes before and after the torrefaction process. Next, the products were placed in a desiccator, and after reaching ambient temperature, weighed to determine mass loss.

231 RESULTS AND DISCUSSION Figure 1 shows the mass loss of the tested materials after the torrefaction process, expressed as weight percent based on dry mass of the raw material. The highest weight loss in the assumed conditions of the thermal treatment was characterized by Virginia mallow (42.5%) and rape straw (40.6%), the lowest by sunflower hulls (13.9%). The values obtained for the other samples ranged between 14.8 - 32.5%. The results were in accordance with a wide range of data presented in the literature [1, 3, 7]. 50

20 Mass loss [%]loss Mass

Figure 1. Value of mass loss after torrefaction process Table 1 summarized the characteristic of fuel properties of the tested raw and torrefied materials - ash content, gross calorific value and net calorific value. In most lignocellulosic materials, after the torrefaction process a high increase of the mineral substances was observed. The greatest increase of the ash content was recorded in the rape straw and mustard straw, respectively from 9.6 to 15.9% and from 11.6% to 16.1%. Such a significant increase in the mineral content could be explained by weight loss of the analyzed materials during the thermal treatment. Table 1. Characteristic of fuel properties of raw and torrefied materials Raw materials Torrefied materials Gross Net Gross Net Ash calorific calorific Ash calorific calorific Material value value value value Ad Qgr,d Qdaf Ad Qgr,d Qdaf wt.% MJ/kg MJ/kg wt.% MJ/kg MJ/kg cereal straw 3.1 18.3 17.0 4.3 19.9 19.5 grass stalks (hay) 5.1 19.4 19.0 8.0 20.5 21.2 hemp straw 2.6 18.4 17.5 3.7 19.7 19.2 miskanthus straw 6.8 17.9 17.9 6.9 18.4 18.5 mustard straw 11.6 17.6 18.5 16.1 18.9 21.3 rape seeds 7.4 20.1 20.2 10.2 22.4 23.7 rape straw 9.6 17.7 18.2 15.9 18.7 21.1 sunflower hulls 2.8 20.2 19.3 3.5 21.0 20.5 tobacco stalks 3.3 19.3 18.5 3.7 19.6 19.1 Virginia mallow straw 5.0 18.7 18.3 8.0 19.1 19.6 willow 2.0 19.1 17.9 2.3 19.7 18.9

d - dry basis daf - dry, ash-free basis

232

Table 2. Elemental analysis of raw and torrefied materials Raw materials Torrefied materials

Material Cd Hd Nd Sd Cld Cd Hd Nd Sd Cld wt.% wt.% wt.% wt.% wt.% wt.% wt.% wt.% wt.% wt.% cereal straw 47.7 6.1 0.2 0.06 0.03 50.4 5.5 0.5 0.07 0.05 grass stalks (hay) 48.8 6.2 1.9 <0.01 0.30 52.8 4.7 2.1 0.20 0.30 hemp straw 45.4 6.1 0.5 0.03 0.50 50.0 5.3 0.5 0.04 0.20 miskanthus straw 43.9 5.8 0.8 0.09 0.20 48.4 5.6 1.0 0.10 0.20 mustard straw 44.1 5.5 2.1 0.60 1.60 47.2 4.8 3.1 0.80 2.10 rape seeds 47.6 6.4 6.2 0.20 0.03 53.4 5.2 7.5 0.70 0.03 rape straw 43.9 5.9 0.9 0.50 1.10 50.0 4.2 1.3 0.90 1.30 sunflower hulls 49.2 6.2 0.7 0.10 0.10 52.6 5.7 0.6 0.10 0.08 tobacco stalks 47.4 6.2 0.5 0.04 0.02 49.4 5.5 0.6 0.06 0.01 Virginia mallow straw 46.0 6.1 0.5 0.07 0.10 50.8 4.9 0.6 0.08 0.10 willow 49.6 6.0 0.7 0.06 0.01 51.4 5.4 0.9 0.07 0.03 d - dry basis Elemental analysis (Table 2) shows a significant increase the share of carbon in a materials after torrefaction process (6.1% in rape straw and 5.8% in rape seeds). In other lignocellulosic materials the increase of carbon was from 1.8% to 4.8%. At the same time the decrease (from 0.2% to 1.7%) of the hydrogen content after the torrefaction process was observed. The carbon content in analyzed raw materials ranged from 43.9% (rape straw and miscanthus) to 49.6% (willow) and from 47.2% (mustard) to 53.4% (rape seeds) in torrefied materials. The share of hydrogen in starting materials was in the level of 5.5÷6.4% (in mustard and rape seeds) and after the torrefaction process: 4.2÷5.7% (in rape straw and sunflower hulls). The nitrogen content in most of the raw materials ranged from 0.2% (cereal straw) to 0.9% (rape straw). Only three materials had the higher concentration of this element (hay – 1.9%, mustard – 2.1%, rapeseed – 6.2%). Torrefaction process had influence to the increase of the nitrogen in the tested materials which is probably associated with their weight loss. In torrefied materials nitrogen content ranged from 0.5% in hemp straw to 7.5% in rape seeds. A similar relationship was found in case of sulfur and chlorine content. The determined total sulfur ranged from <0.01% for grass stalks to 0.6% in mustard. In torrefied materials it was from 0.04% to 0.8%, respectively in the hemp straw and mustard. The chlorine content in the raw materials ranged from 0.01% (willow) to 1.6% (mustard), while in the thermally modified samples: 0.01÷2.1% (tobacco stalks and mustard). The increase of coalification level of the products in the torrefaction process resulted in most of the tested materials higher calorific values (Table 1). Gross calorific value (on dry basis) determined in the raw materials ranged from 17.6 MJ/kg in mustard straw to 20.2 MJ/kg in sunflower hulls. Net calorific value (on dry and ash free basis) was from 17.0 MJ/kg in cereal straw to 20.2 MJ/kg in rapeseeds. In the torrefied samples the determined parameters were on the higher levels. The gross calorific value in these materials was from 18.4 MJ/kg (miscanthus) to 22.4 MJ/kg (rapeseeds) and the net calorific value: 18.5÷23.7 MJ/kg. The highest increase in the net calorific value parameter was found in case of rapeseeds (from 20.2 to 23.7 MJ/kg) which can be related to a significant increase of coalification of this material: from 47.6% to 53.4%. The advantage of fuels produced from torrefied materials is their better hydrophobicity. The aim of absorption test was to compare the resistance of raw and torrefied materials to water absorption under full immersion conditions. Figure 2 shows the test results.

233 It can be concluded that the torrefied materials have a considerably higher resistance to water absorption than the raw materials, not undergone to thermal modification.

1000 raw material torrefied material 800

600

400 Water absorption [%] absorption Water

200

Figure 2. Water absorption of analyzed materials

SUMMARY Based on laboratory tests it was found that the thermal treatment of the lignocellulosic materials carried out under an inert atmosphere (nitrogen), was able to provide solid biofuels with improved fuel properties. It was found that in the analyzed modified materials the ash content was increased, which was a result of a weight loss after the thermal processing of these materials. Furthermore, due to a higher level of coalification of the torrefied materials, the increased of the net calorific value was observed. This was in the range from 0.5 MJ/kg (tobacco stalks and miskanthus straw) to 3.5 MJ/kg (rape seeds). It can be concluded that a significant result of the torrefaction was the better resistance of the torrefied materials for the water absorption. The results indicated the need for further research which will be aimed to obtained solid biofuels with enhanced fuel properties, particularly in terms of parameters of the torrefaction (temperature and processing time).

REFERENCES 1. BERGMANN P.C.A. (2005): Combined torrefaction and pelletisation, The TOP process, ECN-C-05-073; 2. BERGMANN P.C.A., KIEL J.H.A. (2005): Torrefaction for biomass upgrading, ECN- RX-05-180; 3. PRINS M.J. (2005): Thermodynamic analysis of biomass gasification and torrefaction; 4. VAN DER STELT M.J.C., GERHAUSER H., KIEL J.H.A., PTASINSKI K.J. (2011): Biomass upgrading by torrefaction for the production of biofuels: A review. Biomass and Bioenergy, 35, 3748-3762;

234 5. TUMULURU J.S., SOKHANSANJ S., HESS J.R., WRIGHT C.T., BOARDMAN R.D. (2011): A review on biomass torrefaction process and product properties for energy applications, Industrial Biotechnology, 7, 5, 384-401; 6. MEDIC D., DARR M., SHAH A., POTTER B., ZIMMERMAN J. (2012): Effects of torrefaction process parameters on biomass feedstock upgrading, Fuel, 91, 147-154 7. LIPINSKY E.S., ARCATE J.R., REED T.B. (2002): Enhanced wood fuels via torrefaction, Fuel Chemistry Division Preprints, 47, 1, 408; 8. BERGMANN P.C.A., BOERSMA A.R., KIEL J.H.A., PRINS M.J., PTASINSKI K.J., JANSSEN F.J.J.G. (2005): Torrefaction for entrained-flow gasification of biomass, ECN-C-05-067; 9. BERGMANN P.C.A., BOERSMA A.R., ZWART R.W.R, KIEL L.H.A. (2005): Torrefaction for biomass co-firing in existing coal-fired power station. Biocoal, ECN-C- 05-013; 10. XIE YAN-JUN, LIU YI-XING, SUN YAO-XING (2002): Heat-treated wood and its development in Europe, Journal of Forestry Research, 13[3], 224-230. 11. AHAJJI A., DIOUF P.N., ALOUI F., ELBAKALI I., PERRIN D., MERLIN A., GEORGE B. (2009): Influence of heat treatment on antioxidant properties and colour stability of beech and spruce wood and their extractives, Wood Science Technology, 43, 69-83; 12. WITCZAK M., WALKOWIAK M., CICHY W. (2011): Pre-treatment of biomass by torrefaction preliminary studies, Drewno. Prace naukowe. Doniesienia. Komunikaty., 54, 185, 89-96; 13. EN 14775:2010 Solid biofuels – Determination of ash content; 14. PN EN ISO 16948:2015 Solid biofuels – Determination of total content of carbon, hydrogen and nitrogen; 15. PN EN ISO 16994:2015 Solid biofuels – Determination of total content of sulphur and chlorine; 16. EN-14918:2010 Solid biofuels – Determination of calorific value.

235

Streszczenie: Modyfikacja termiczna cząstek lignocelulozowych w celu otrzymania biopaliw stałych o ulepszonych właściwościach. Celem pracy było poznanie wpływu wstępnej obróbki termicznej roślinnych surowców lignocelulozowych na właściwości otrzymanych biopaliw stałych. Badaniami objęto następujące materiały lignocelulozowe: słoma gorczycy, słoma konopi, łodygi traw (siano), łodygi tytoniu, łuski słonecznika, słoma miskantusa, słoma rzepakowa, słoma zbożowa, łodygi ślazowca pensylwańskiego, śruta rzepakowa i zrębki wierzby energetycznej. Proces modyfikacji termicznej prowadzono przez 30 minut w temperaturze 220°C w atmosferze azotu. Po zakończeniu toryfikacji określono ubytek masy surowców. Dalsze analizy obejmowały oznaczenia popiołu, składu elementarnego (zawartość C, H, N, S i Cl), ciepła spalania, absorpcji wody i wyznaczenia wartości opałowej. Stwierdzono, że wzrost zawartość popiołu w materiałach toryfikowanych jest efektem ubytku masy. Analiza elementarna wykazała wzrost udziału węgla, przy jednoczesnym spadku udziału wodoru w próbach modyfikowanych termicznie. Wzrost uwęglenia produktu względem surowca wyjściowego skutkował większymi wartościami ciepła spalania oraz wartości opałowych. Materiały toryfikowane wykazywały znacznie wyższą odporność na absorpcję wody niż surowce nie poddane modyfikacji termicznej. Analiza wyników wykazała, że badane toryfikowane materiały lignocelulozowe mają korzystniejsze właściwości paliwowe niż surowce nie poddane obróbce termicznej.

Corresponding author: Małgorzata Walkowiak Magdalena Witczak Wojciech Cichy Wood Technology Institute Winiarska Street, no. 1, 60-654 Poznań E-mail address: [email protected] [email protected] [email protected] Phone: +48 61 849 24 78 +48 61 849 24 31

236 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 237-240 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Mechanical properties of one-layer experimental particleboards from shoots of tall wheatgrass and industrial wood particles

KRZYSZTOF WARMBIER1), LESZEK DANECKI2), WŁODZIMIERZ MAJTKOWSKI3)

1)Institute of Technology, Kazimierz Wielki University in Bydgoszcz 2)Research and Development Centre for Wood-Based Panels Industry in Czarna Woda 3)Plant Breeding and Acclimatization Institute, Research Division in Bydgoszcz

Abstract: Mechanical properties of one-layer experimental particleboards from shoots of tall wheatgrass and industrial wood particles. One-layer particleboards have been produced using tall wheatgrass Agropyron elongatum and industrial pine chips. Variable parameters were: proportion of tall wheatgrass chips (0, 12.5, 25, 50, 75, 100%) and the resin content (8 and 10%). The modulus of elasticity (MOE), modulus of rupture (MOR) and internal bond (IB) were studied. These properties decreased with an increase in the share of tall wheatgrass shavings and increased for the appropriate amount of glue.

Keywords: particleboard, tall wheatgrass, mechanical properties, resin content

INTRODUCTION In many countries, including Poland, the production of particleboards is constantly rising. Particleboards are the most commonly used wood composite. A shortage of forest resources makes it necessary to seek alternative cellulose materials for the production of particleboards. Kurowska, Borysiuk (2009) in their study took into account the use of hay as a substitute for chips used for the inner layers of three-layer boards. It was found that 20% of hay decreases the bending strength and modulus of elasticity. At the same time, these boards were characterised by density distribution in the cross-section similar to the distribution of the density for control boards made in 100% from chips. The possibility of using cut grass for the manufacture of particleboards was demonstrated in a study by Nemli and others (2009). One of the possible alternatives may be raw material grown for energy purposes namely tall wheatgrass Agropyron elongatum. The usefulness of wheatgrass has been the subject of research by scientists from the University of California in the USA. Yi Zheng and others (2007) took into account different types of glue (PDMI and UF) and the density of the boards. It was found that with an increase in the density of the particleboards, mechanical properties improve. Some efforts have been made to eliminate the heavy layer of wax that occurs on these plants. A typical commercial particleboard is a three-layer board, which consists of the inner layer and two external layers. The characteristics of these layers vary significantly. External layers, made of smaller particles of higher resin content, have a greater ratio of concentration and density, and consequently better mechanical properties. External layers are extremely important in the transmission of the load in components made of particleboards. When these objects are subjected to bending, external layers transfer more than two-thirds of the bending moment. We assume that the particles of wheatgrass as a substitute for wood particles will be used only for the internal layer of three-layer particleboards. In this case, a comparative study of the properties of three-layer particleboards with the internal layer made of wheatgrass and industrial particles would be inefficient. Therefore, it was decided to examine one-layer particle boards as a simulation of the inner layer of a three-layer board.

237 The purpose of this study was to evaluate some mechanical properties of one-layer particleboards made from tall wheatgrass Agropyron elongatum and industrial wood particles with different proportions of wheatgrass particles and different levels of resin.

MATERIALS Raw material for the study consisted of stems of tall wheatgrass Agropyron elongatum and industrial pine wood particles. The annual wheatgrass stalks were collected from the experimental field in Bartążek near Olsztyn. Stem diameter ranged between 3-5 mm and the height of about 2 m. Stems were stored in open air in special bales and then chipped in a hammer mill. The industrial pine particles were supplied by Pfleider Prospan in Wieruszów (Poland). The pine particles were sieved in a shaker using 4 and 1 mm sieves. Particles that had passed through the 4 mm sieve and remained in the 1 mm sieve were used to produce experimental one-layer particleboards to simulate the internal layer of a three-layer board. The particles were dried for moisture content below 3%.

Table 1.Manufacturing parameters

Board thickness 10 mm Board dimensions 40 cm x 40 cm Target board density 550 kg/m3 Press temperature 1800C Maximum pressure 2.5 MPa Press closing time 20 s Pressing time 3,20 min

Adhesive resin Silekol 310 was used, which is a mixture of polymers of urea, melamine and formaldehyde in aqueous solution. The board manufacturing parameters are listed in Table 1. Two levels of resin content were assumed: 8 and 10%. The ratio of the wheatgrass particles to the industrial wood particles was another variable factor. Six values of this indicator were adopted: 0, 12.5, 25, 50, 75 and 100%. All boards were stored under controlled conditions (50% relative humidity and a temperature of 200C) for a period of two weeks. Samples were cut from the boards, on the basis of which the following mechanical properties were determined in accordance with the relevant EN standards: modulus of elasticity (MOE) and modulus of rupture (MOR) (EN 310, 1993) and internal bond (IB) (EN 319, 1993). 20 samples were prepared for each variant.

RESULTS Density is one of the factors affecting the properties of particleboards. The target density was 550 kg/m3, however, the true density of individual boards was in the range 528 to 571 kg/m3, and the standard deviation was 16 kg/m3. Given this small change in the density of the boards, its influence on the mechanical properties was not taken into account. Mean values of mechanical properties of the studied particleboards is presented in Figure 1. Error bars represent standard deviation for the twenty samples. The two variables, the contents of the wheatgrass particles and resin content in the particleboard significantly affect all specified mechanical properties (MOE, MOR and IB). The mechanical properties of bending strength of particle boards (MOE and MOR) gradually decreased with increasing particle content of wheatgrass from 0% to 100%. For control boards made from 100% pine shavings and 10% resin content, these values for a resin content of 8% were respectively lower by 19.8% and

238

Figure 1. Mechanical properties of particleboards

239 13%. MOE of particleboards containing 25% of wheatgrass particles was on average lower by 4.3 for 10% of resin content and 0.8% for the resin content of 8%. In contrast, MOR decreased by 10 and 8.9% respectively. Another mechanical property IB also decreased with the increase of the share of wheatgrass particles. For the control boards with resin content of 10% the values were higher by 13.2% than the boards with 8% resin content. Increasing the resin content from 8% to 10% significantly improved mechanical properties of particleboards.

CONCLUSION One-layer experimental particle boards were produced using particles made from tall wheatgrass Agropyron elongatum as a substitute for industrial chips made from pine wood. Since these boards were to simulate the inner layer of typical three-layer boards, pine shavings were made with fraction of 4 > F > 1 mm. Wheatgrass particle content had a significant impact on all mechanical properties (MOE, MOR and IB). Tall wheatgrass particles can be used as a substitute for pine wood added to the inner layer of three-layer particleboards.

REFERENCES 1. EN 310, 1993: Wood-based panels. Determination of modulus of elasticity in bending and of bending strength. 2. EN 319, 1993: Particleboards and fiberboards. Determination of tensile strength perpendicular to the plane of the board. 3. KUROWSKA A., BORYSIUK P., 2009: Particleboards with grass plant additive. Ann. WULS-SGGW, Forestry and Wood Technology. 68:463-466. 4. NEMLI G., DEMIREL S., GUMUSKAYA E., ASLAN M., ACAR C., 2009: Feasibility of incorporating waste grass clippings (Lolium perenne L.) in particleboard composites. Waste Management 29: 1129-1131. 5. WILCZYŃSKI A., WARMBIER K., DANECKI L., MROZEK M., 2011: Properties of experimental particleboards with the core layer made from willow (Salix viminalis). Ann WULS-SGGW, Forestry and Wood Technology: 194-198. 6. ZHENG P., PAN Z., ZHANG R., JENKINS B.M., BLUNK S., 2007: Particleboard quality characteristics of saline jose tall wheatgrass and chemical treatment effect. Bioresource Technology 98: 1304-1310.

Streszczenie: Właściwości mechaniczne eksperymentalnych jednowarstwowych płyt wiórowych wytworzonych z pędów perzu wydłużonego i wiórów przemysłowych. Wykonano jednowarstwowe płyty wiórowe stosując wióry perzu wydłużonego Agropyron elongatum i przemysłowe wióry sosnowe. Parametrami zmiennymi były: udział wiórów perzu wydłużonego (0, 12.5, 25, 50, 75, 100%) i stopień zaklejenia (8 i 10 %). Badano moduł sprężystości (MOE), wytrzymałość na zginanie (MOR) i wytrzymałość na rozciąganie poprzeczne. (IB) Właściwości te malały ze wzrostem udziału wiórów perzu wydłużonego i rosły dla odpowiedniego stopnia zaklejenia.

Corresponding author:

Krzysztof Warmbier Institute of Technology, Kazimierz Wielki University Chodkiewicza 30 85-064 Bydgoszcz, Poland e-mail: [email protected]

240 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 241-248 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Impact of structures of selected lounge furniture seats on the comfort of use

KRZYSZTOF WIADEREK, ŁUKASZ MATWIEJ, MARIKA DETTLAFF Department of Furniture Design, Faculty of Wood Technology, Poznań University of Life Sciences

Abstract: Impact of structures of selected lounge furniture seats on the comfort of use. The main objective of the study was to determine the impact of structures of four seats on comfort during short-term use. Fifty-five volunteers participated in the tests in which the Force Sensitive Applications sensing mat was used to record contact pressure. Each person completed a survey in order to describe their feelings of comfort. On the basis of the laboratory tests and the survey, it was found that application of various types of supporting layers influences seat comfort and quality of use.

Keywords: seat, lounge furniture, seating furniture, contact pressure, survey, comfort

INTRODUCTION The structure of a seat, its shape and softness, height of the usable surface, furniture type and time spent on it determine the comfort of use. However, it is necessary to define the terms: comfort and discomfort. Comfort is a state of subjective pleasure resulting from a reaction to an environment or a situation. Nevertheless, it should be assumed that comfort and discomfort are two various opposites on a given scale including extreme discomfort, transitory state and extreme comfort (Vlaović, Bogner, Grbac, 2008). A fundamental aspect in upholstered furniture is an anthropotechnic system which results from the combination of two elements - a human body and a seat, causing their direct interaction which is unusual when using other pieces of furniture (Smardzewski, 2010). The human exerts pressure on the surface and the surface exerts pressure on the body. In a sitting position, the greatest pressure is caused by ischial tuberosities. Pressure on soft tissues of the human body during sitting influences the feeling of discomfort, what with time can intensify pressure pain caused by the closing of blood vessels. Blood vessels close when pressure is 32 mm Hg (Krutul, 2004). The objective of the study was to determine the impact of structures of selected lounge furniture seats on short-term comfort of use on the basis of the experimental tests with the participation of volunteers who used the sensing mat, and the survey.

MATERIALS The subject of the tests included four seats of the same dimensions of 480x580x140 [mm] varying in terms of the structure. Static factors during the research were: seat dimensions, a place of pressure measurement, a height of the usable surface, upholstery frame dimensions, a type of upholstery fabric, places of fabric stitching, weight of wadding, felt and an interlining fabric. Dynamic factors were: a type of supporting layer, a type of spring layer, respondent anthropometric data. The tests included the observations of: the distribution and values of contact pressure as well as an active body contact surface of the seat. The structures of the analyzed seats are presented in Figures 1-4. The structural difference involved changes in a supporting layer such as: webbing straps, fibreboard and a wave spring.

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Fig 1. Cross-section of Seat I: 1-upholstery frame, 2-interlining fabric, 3-polyurethane foam T35/42, 4-polyurethane foam T35/42, 5-felt, 6-wadding, 7-Bonnell spring unit, 8-upholstery fabric, 9-webbing straps

Fig 2. Cross-section of Seat I: 1-upholstery frame, 2-interlining fabric, 3-polyurethane foam T35/42, 4-polyurethane foam T35/42, 5-felt, 6-wadding, 7-Bonnell spring unit, 8-upholstery fabric, 9-fibreboard

Fig 3. Cross-section of Seat I: 1-upholstery frame, 2-interlining fabric, 3-polyurethane foam T35/42, 4-polyurethane foam T35/42, 5-felt, 6-wadding, 7-Bonnell spring unit, 8-upholstery fabric, 9-wave spring

The test station was equipped with a computer with the Force Sensitive Applications software (FSA), the FSA sensing mat, a measure to check a popliteal height, four seats placed evenly so that the height of a seat was 438 mm in accordance with Atlas miar człowieka by Gedliczka [Atlas for Human Measurements] (2001) for a 50th centile male adult. A tool to measure pressure was the sensing mat of the dimensions of 660x660 mm with the system of 32x32 sensors and the Force Sensitive Applications software. Each volunteer took the position on a seat twice: first, on the sensing mat placed directly on each seat and second, on a seat without the mat. It was necessary to sit twice as the mat hinders the feelings of comfort and seat softness which users were asked about in the survey. In the analysis, the seat pressure distribution coefficient (SDP) and discomfort coefficient were used and are calculated with the use of the following formulas (Matwiej, Wiaderek, Szczechowiak, 2015):

242 SPD= [%] where: n - number of sensors in which contact pressure has non-zero values - contact pressure in any mat sensor; - average contact pressure for n sensors, and the discomfort coefficient D according to the formula:

D= [daN/m4] A- contact surface; - average contact pressure for n sensors; SPD- seat pressure distribution coefficient.

Fig 5. Test station

The test was conducted among 55 people of various anthropometric measurements. The first task of each user was weighing and measuring and then, taking position in the test station (Fig 5). The test recording the image of the mat on one seat lasted for around 90 seconds. After that time, a volunteer one more time took the position on the seat without the mat and without the time limit, but for no shorter than 90 seconds. Analogically, the procedure was repeated for a next seat with the same user. The survey included the following issues and questions, for example: - sex, height, weight - How do you assess the softness of the seat? - How do you assess the comfort of the seat? - Which seat would you choose when purchasing lounge furniture?

RESULTS The laboratory tests enabled the observation of diverse pressure distribution and values for the analyzed seats with each person. The tests resulted in creating the maps of pressure distribution on a seat surface.Figures 6-9 show the maps of pressure distribution for various seat structures. All given examples concern the same examined person - a selected male adult of the height of 1900 mm, the weight of 85 kg and the popliteal height of 490 mm. The analysis of the data of a given case shows that the value of average pressure on a sensor was highest in the case of Seat II, that is 7.66 kPa. When it comes to Seat I, this value was lower,

243 that is 6.56 kPa. In the case of the remaining structures: the value for Seat III was 6.76 kPa and 7.55 kPa for Seat IV. The selected list of results and presented values are representative in relation to the average results obtained during the test of 55 volunteers.

Fig 6. Map of pressure on Seat I

Fig 7. Map of pressure on Seat II

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Fig 8. Map of pressure on Seat III

Fig 9. Map of pressure on Seat IV

The analysis of all results enabled calculating the average distribution of pressure appearing on the contact surface of the body with the surface of the analyzed seats. The values of the discomfort coefficient D were calculated and average values are presented in the graph below

245 (Fig 10). The analyzed case with the lowest discomfort coefficient was Seat I (47.17 daN/m4). Seat IV received a similar value of 47.36 daN/m4. The highest discomfort coefficient was found for Seats II (51.32 daN/m4), whereas Seat III obtained a similar value of 51.21 daN/m4. A high discomfort coefficient means that the seat structure is less comfortable. The lower the discomfort coefficient is, the more comfortable the seat is.

Fig 10. Comparison of average discomfort coefficients D for all seats

During the subjective test, the respondents selected Seats I and IV. Each seat was chosen by 31% of the respondents (Fig 11). The structure option least often selected, that is by only 13% of the respondents, was Seat II. When analyzing the preferred seat by a given person in terms of pressure distribution and the calculated discomfort coefficient, the objective selection list was prepared (Fig 12). According to the tests on the sensing mat, the best seat was Seat I preferred by 47% of the respondents. Seat IV was preferred by 35% of the respondents, whereas options II and III were chosen by just 9%.

Fig 11. Percentage distribution of subjective seat selection

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Fig 12. Percentage distribution of objective seat selection

There is a clear impact of the seat structure on pressure distribution, thus on comfort and the quality of use. The tests with the sensing mat showed that the structure of Seat I was most comfortable according to the researched group. At the same time, this result corresponds to the subjective selection in 66%. In terms of the discomfort coefficient D as well as the pressure distribution coefficient, the more favourable values were obtained by Seat IV with the Bonnell spring unit filling. Seat III, whose structure differs as it does not have the Bonnell spring unit, had the level of discomfort worse by 7.6%. This comparison directly indicates the improvement of comfort of seats with an additional filling in the Bonnel spring unit consisting of high-resilience foam HR32/30.

REFERENCES

1. Gedliczka A. (2001) Atlas miar człowieka. Dane do projektowania i oceny ergonomicznej. Centralny Instytut Ochrony Pracy, Warszawa 2. Krutul R. (2004) Odleżyna, profilaktyka i terapia. Revita 3. Matwiej Ł.,Wiaderek K., Szczechowiak A. (2015) Project of lumbar area stiffness regulator for an upholstered bed enabling the minimalization of user's discomfort. Annals of Warsaw University of Life Sciences - SGGW 92, Warszawa 4. Smardzewski J. (2010): Niektóre biomechaniczne aspekty w projektowaniu mebli do wypoczynku i snu. Prace i materiały IWP nr 23. Instytut Wzornictwa Przemysłowego. Warszawa 5. Vlaović Z., Bogner A., Grbac I. (2008) Comfort Evaluation as the Example of Anthropotechnical Furniture Design. Coll Antropol. 32, Zagrzeb, s 277-283

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Streszczenie: Wpływ konstrukcji wybranych siedzisk mebli do wypoczynku na komfort użytkowania. Głównym celem pracy było określenie wpływu konstrukcji czterech siedzisk na komfort podczas ich krótkiego użytkowania. Badania były przeprowadzone przy użyciu maty sensorowej Force Sensitive Applications z odczytem naprężeń kontaktu z udziałem 55 wolontariuszy. Każda osoba wypełniała ankietę w celu określenia odczuć komfortu. Na podstawie przeprowadzonych badań laboratoryjnych i ankietowych stwierdzono, iż zastosowaniowe różnego typu warstwy podtrzymującej wpływa na komfort i jakość użytkowania siedzisk.

Corresponding author:

Krzysztof Wiaderek, Łukasz Matwiej Uniwersytet Przyrodniczy w Poznaniu, Wydział Technologii Drewna Wojska Polskiego 38/42 60-627 Poznań, [email protected] [email protected]

248 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 249-255 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The production potential of the furniture market in Poland MAGDALENA WIĘCKOWSKA Faculty of Forestry in Hajnówka, Bialystok University of Technology (PB) EMILIA GRZEGORZEWSKA Department of Technology and Entrepreneurship in Wood Industry Faculty of Wood Technology, Warsaw University of Life Sciences (SGGW)

Abstract: The paper shows the comparative analyses relating to the production potential of the furniture market and manufacturing in Poland. Furniture industry among others also falls within that category. Therefore selected indicators of economic production, i.e.: production sold, the average level of employment in a given year, dynamics of productivity growth measured as output per 1 employee, were used. Moreover, the diversion in the manufacture of furniture were presented. Time range of research adopted for 2009-2014.

Keywords: manufacturing, furniture industry, sold production, employment status, production productivity

INTRODUCTION Wood sector plays an important role in Polish economy [Grzegorzewska E. 2013, p. 308]. Especially the furniture industry which since the nineties is one of the fastest growing sectors of the processing industry in Poland. The furniture branch sells 90% of its production heading abroad [Grzegorzewska E. and Więckowska M. 2015, p. 111]. Poland recorded a significant increase in the production of furniture in 1997-2006 - an average of 11.5 % growth per year [Grzegorzewska et al. 2012, p. 55]. The most spectacular results in Polish economy, the furniture industry reached in the years 1995-2000. During that period the average annual growth rate of sold production fluctuated around 25-30% [GUS 1996, 1997, 1998, 1999, 2000, 2001]. In 2000-2005, the growth rate slowed down (to approx. 6-7%), but still maintained a clear growth trend [GUS 2001, 2002, 2003, 2004, 2005, 2006]. Only in the period 2000-2002 macroeconomic crisis reflected on the results of the sector negatively. However, after that period the furniture branch was able to adapt to new conditions. Already in 2003, in relation to 2002, it reported 30% increase in sold production. In the next years the positive growth rate was maintained in the branch. Nevertheless the growth of sold production in relation to the successive years was never again equally spectacular (ranged from 19% in 2004 to 2.9% in 2008) [GUS 2005, 2006, 2007, 2008, 2009]. The next crisis - in 2008-2009 - affected less adversely the financial liquidity position and debt of furniture companies with the highest level of employment [Grzegorzewska E. and Stasiak – Betlejewska R. 2014, p. 322]. However the branch, despite the downturn in global markets, continued growth in sold production value. Moreover there is worth to note that in the furniture industry in sold production regularly occurs the seasonal fluctuations. A characteristic feature of seasonality was the increase in sales in four months during the year (March, September, October and November) and decrease in the remaining eight months [Gawrońska A. 2015, p. 15; Olkowicz M. 2013, p. 66] Average approx. 30% of annual furniture sold production falls on the period from September to November, i.e. three autumnal months [Olkowicz M. 2013, pp. 66 – 67]. Indicators of the furniture industry development and the whole Polish economy confirm on the one hand, the high growth potential of the furniture sector, but on the other hand - high variability of growth rates indicates on immaturity of the sector. Moreover despite such good economic results of the furniture branch, also the specific character of Polish furniture enterprises is very diverse [Więckowska M. 2015, p. 96]. Therefore, referring to

249 determinants mentioned above, this article tackles the subject of researching the potential of the furniture industry in the next period, i.e. 2009-2014.

OBJECTIVE AND RESEARCH METHODOLOGY The primary objective of the analysis was to determine the production potential of the furniture industry against the background of industrial processing. The study covered the years 2009-2014. In the conducted analyses the following indicators were used: production sold, the average level of employment in a given year, dynamics of productivity growth measured as output per 1 employee. Moreover, trends in the manufacture of furniture were presented. According to GUS methodology sold production concerns the total activity of an economic entity, i.e., both industrial and non-industrialproduction. Sold production of industry includes [GUS 2015]: − the value of finished products sold (regardless of whether or not payments due were received for them), semi-finished products and parts of own production; − the value of paid work and services rendered, i.e. both industrial and non-industrial; − flat agent’s fee in the case of concluding an agreement on commission terms and full agent’s fee in the case of concluding an agency agreement; − the value of products in the form of settlements in kind; − products designated for increasing the value of own fixed assets. Gross value added accounts for the portion of output manufactured in industry that remains after deducting the value of intermediate consumption.

RESEARCH RESULTS As results from research conducted by the Central Statistical Office, in 2009 sold production of the furniture industry amounted to 27.7 billion PLN, which means that its share in the manufacturing sector stood at 3.7% (Fig. 1).

1200 40 1000 35 30 800 25 600 20 400 15 10 200 5 0 0 2009 2010 2011 2012 2013 2014 Manufacturing 741.7 815 950.4 985.3 993.7 1028.4 Furniture industry 27.7 25.7 30.2 28.8 31.6 35.3

Figure 1. Furniture sold production against the background of manufacturing in the years 2009-2014 [billion PLN] Source: Statistical Yearbook of Industry - Poland 2010-2015

In the considered period, sold production of the processing industry was growing year- on-year. At the end of the period it amounted to 1028.4 billion PLN and was by 38.7% higher than five years earlier. The highest growth in this area (116.6%) was observed in 2011. On the other hand, the sold production of furniture increased considerably by 27.4% and in 2014 amounted to 35.3 billion PLN. However it should be noticed, that a decrease of furniture sold production was noted in 2010 and 2012, respectively by 7.3% and 4.6%. In contrast, the highest growth rate in this area, which came to 117.5%, furniture industry achieved in 2011.

250 Another indicator, which was analyzed in the process of evaluating the production potential, was the average level of employment in the furniture industry against a background of manufacturing (Fig. 2).

2300 155.0 2250 150.0 2200 145.0 2150 140.0 2100 135.0 2050 130.0 2000 125.0 2009 2010 2011 2012 2013 2014 Manufacturing 2261.7 2229.8 2251.2 2217.7 2186.6 2091.3 Furniture industry 151.0 144.9 144.3 138.6 137.2 133.9

Figure 2. The average level of employment in the furniture industry against the background of manufacturing [thous. persons] Source: Statistical Yearbook of Industry - Poland 2010-2015

In the period 2009-2014 the number of people employed in the furniture industry fell by 11.3%, from 151.0 to 133.9 thous. people. Considering the criterion of employment, participation of the furniture enterprises in manufacturing decreased slightly from 6.7% to 6.4%. The largest 4% drop was recorded in these companies in 2010 and 2012. Similar trends were observed for manufacturing. The employment level in the considered period decreased by 7.5%. In 2014 were employed 2091.3 thous. people, which mean, that from the beginning of the period, the employment decreased of more than 170 thous. It is worth noting that throughout the period covered by the study, with the exception of 2011, in the manufacturing recorded a negative trend in the employment. The largest decline (4.4%) took place in 2014. In addition to the employment level, important information on the production potential of enterprises delivers also labour productivity measured by output per 1 employee. In 2014 that indicator in the furniture industry enterprises amounted to 239.2 thous. PLN and was almost twice lower than in manufacturing (462.7 thous. PLN). As appears from the figure 3, the dynamics of the labor productivity growth in the furniture industry measured by sold production per 1 employee was variable. In 2011, 2013 and 2014 observed increase in this indicator - the growth was respectively 116.0% and 111.5%. In other years the trend has been reversed, however it should be noted that the declines were slight and did not exceed 3%. In turn, in the manufacturing a growth rate of labor productivity measured by the value of sold production per 1 employee was being observed from year by year. In 2010-2011, the companies active in the processing industry achieved the best results. This productivity indicator amounted to 111.8% (2010) and 107.8% (2011).

251 120.0 115.0 110.0 105.0 100.0 95.0 90.0 85.0 2009 2010 2011 2012 2013 2014 Manufacturing 103.0 111.8 107.8 102.1 103.4 102.8 Furniture industry 99.9 97.0 116 97.0 111.5 106.4

Figure 3. The dynamics of labor productivity measured by the value of sold production per 1 employee [%] Source: Statistical Yearbook of Industry - Poland 2010-2015

The production potential of the furniture industry also is determined by the production scale, i.e. the volume of pieces of furniture manufactured in a given period. In 2009 in the furniture industry was produced in total more than 17.8 million pieces of wooden furniture for dining and living room (table 1). Throughout the period covered by the analysis this category of products was ranked first in regard to the highest quantity of manufactured pieces of furniture. In 2014 their production amounted to 23.6 million units. Upholstered seats used in the house were located on the second position. Moreover in 2014 their production exceeded 12 million units and was higher by 6.2% than 5 years earlier.

Table 1. Production of the furniture industry in the period 2009-2014 [thous. units] Itemisation 2009 2010 2011 2012 2013 2014 Seats convertible into beds excluding 1906 2 284 2 581 2 957 3 237 3 597 garden seats or camping equipment Upholstered seats used in the house 11 422 10 495 10 217 11 082 11 077 12 125 Wooden kitchen furniture for fitted 1 661 1 622 938 1 332 834 895 kitchen Other wooden kitchen furniture 2 509 1 854 2 279 3 038 3 246 3 233 Wooden furniture for bedroom 3 380 3 560 3 444 3 645 3 645 5 213 Wooden furniture for dining and 17 826 19 616 20 169 20 505 20 196 23 680 living room Source: Production of Industrial Products in 2014 r., GUS, Warsaw 2015

In the case of other products of the furniture industry the dynamics was higher. The best results in this area obtained for seats convertible into beds and for wooden furniture for bedroom. In the analyzed period, the dynamics of their production volume amounted to 188.7% for the first group and 144.2% for the second one. Exceptions was wooden kitchen furniture for fitted kitchen, which production was nearly 50% less than 5 years earlier.

CONCLUSIONS GUS studies show that in the period 2009-2014 sold production of furniture industry grew by 27.4% and at the end of the period amounted to 35.3 billion PLN. At the same time in the manufacturing was noted the growth by 38.7%. This contributed to a slight decline in share of furniture market in the sold production from 3.7% to 3.4%. In the analyzed period, the number of people employed in the furniture industry decreased by 11.3% from 151.0 to

252 133.9 thous. people. On the other hand, in 2014 in the manufacturing 2091.3 thous. people (in total) found the employment, i.e. by more than 170 thous. less than at the beginning of the period. Thus, taking into account the employment criterion, share of furniture enterprises in the manufacturing decreased slightly from 6.7% to 6.4%. The high production scale also indicates on the significant production potential of the furniture industry. In 2014 the native companies had produced nearly 48.7 million pieces of furniture, more than 10 million units more than 5 years earlier. With this 23.7 million units accounted wooden furniture for dining room and living room, i.e. by 1/3 more than 5 years earlier. The highest increases in production volume were achieved in the case of seats convertible into beds and wooden furniture used in the bedroom. In the analyzed period, the growth rate of production amounted to 188.7% and 144.2%. In summary it can be said that despite the reduction in the level of employment and labor productivity in the furniture industry, there was an increase in the volume of production of Polish furniture industry in the years 2009-2014. In addition, the attention should be paid to the significant increase in the value of production sold in this market. Therefore it can be assumed that in the case of improvement indicators related with employment - the production potential of the furniture market could be utilized in more fully way. In the future it could contribute to achieve even better economic results than in previous years.

Acknowledgements

Research was carried out under development project Implementation of Eco-glueing innovative technology of composite materials veneered asymmetrically, used in furniture production (No. TANGO1/266389/NCBR/2015) financed by The National Centre for Research and Development

REFERENCES

1. GAWROŃSKA A., Seasonality of sold production of furniture in Poland in the years 2004-2015. Intercathedra, No. 31/1, 2015, pp. 11 – 15 2. GRZEGORZEWSKA, E., NIZIAŁEK, I., JENCZYK-TOŁŁOCZKO, I., Assessment of the furniture industry condition in Poland, Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology, No. 78, 2012, pp. 55 – 59. 3. GRZEGORZEWSKA E.: The influence of global economic crisis on import and export of furniture in Poland. Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology, No. 82, 2013, pp. 308 – 312. 4. GRZEGORZEWSKA E., STASIAK – BETLEJEWSKA R., The Influence of Global Crisis on Financial Liquidity and Changes in Corporate Debt of the Furniture Sector in Poland. DRVNA INDUSTRIJA, No. 65/4, 2014, pp. 315 – 322. 5. GRZEGORZEWSKA E., WIĘCKOWSKA M., Profitability change trends in the wood sector in Poland in the years 2008- 2014. Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology, No. 92, 2015, pp. 109 – 112. 6. GUS [1996]: Rocznik Statystyczny Przemysłu 1995 (Statistical Yearbook of Industry - Poland 1995). Zakład Wydawnictw Statystycznych, Warszawa 7. GUS [1997]: Rocznik Statystyczny Przemysłu 1996 (Statistical Yearbook of Industry - Poland 1996). Zakład Wydawnictw Statystycznych, Warszawa 8. GUS [1998]: Rocznik Statystyczny Przemysłu 1997 (Statistical Yearbook of Industry - Poland 1997). Zakład Wydawnictw Statystycznych, Warszawa 9. GUS [1999]: Rocznik Statystyczny Przemysłu 1998 (Statistical Yearbook of Industry - Poland 1998). Zakład Wydawnictw Statystycznych, Warszawa

253 10. GUS [2000]: Rocznik Statystyczny Przemysłu 1999 (Statistical Yearbook of Industry - Poland 1999). Zakład Wydawnictw Statystycznych, Warszawa 11. GUS [2001]: Rocznik Statystyczny Przemysłu 2000 (Statistical Yearbook of Industry - Poland 2000). Zakład Wydawnictw Statystycznych, Warszawa 12. GUS [2002]: Rocznik Statystyczny Przemysłu 2001 (Statistical Yearbook of Industry - Poland 2001). Zakład Wydawnictw Statystycznych, Warszawa 13. GUS [2003]: Rocznik Statystyczny Przemysłu 2002 (Statistical Yearbook of Industry - Poland 2002). Zakład Wydawnictw Statystycznych, Warszawa 14. GUS [2004]: Rocznik Statystyczny Przemysłu 2002 (Statistical Yearbook of Industry - Poland 2003). Zakład Wydawnictw Statystycznych, Warszawa 15. GUS [2005]: Rocznik Statystyczny Przemysłu 2004 (Statistical Yearbook of Industry - Poland 2004). Zakład Wydawnictw Statystycznych, Warszawa 16. GUS [2006]: Rocznik Statystyczny Przemysłu 2005 (Statistical Yearbook of Industry - Poland 2005). Zakład Wydawnictw Statystycznych, Warszawa 17. GUS [2007]: Rocznik Statystyczny Przemysłu 2006 (Statistical Yearbook of Industry - Poland 2006). Zakład Wydawnictw Statystycznych, Warszawa 18. GUS [2008]: Rocznik Statystyczny Przemysłu 2007 (Statistical Yearbook of Industry - Poland 2007). Zakład Wydawnictw Statystycznych, Warszawa 19. GUS [2009]: Rocznik Statystyczny Przemysłu 2008 (Statistical Yearbook of Industry - Poland 2008). Zakład Wydawnictw Statystycznych, Warszawa 20. GUS [2010]: Rocznik Statystyczny Przemysłu 2009 (Statistical Yearbook of Industry - Poland 2009). Zakład Wydawnictw Statystycznych, Warszawa 21. GUS [2011]: Rocznik Statystyczny Przemysłu 2010 (Statistical Yearbook of Industry - Poland 2010). Zakład Wydawnictw Statystycznych, Warszawa 22. GUS [2012]: Rocznik Statystyczny Przemysłu 2011 (Statistical Yearbook of Industry - Poland 2011). Zakład Wydawnictw Statystycznych, Warszawa 23. GUS [2013]: Rocznik Statystyczny Przemysłu 2012 (Statistical Yearbook of Industry - Poland 2012). Zakład Wydawnictw Statystycznych, Warszawa 24. GUS [2014]: Rocznik Statystyczny Przemysłu 2013 (Statistical Yearbook of Industry - Poland 2013). Zakład Wydawnictw Statystycznych, Warszawa 25. GUS [2015]: Rocznik Statystyczny Przemysłu 2014 (Statistical Yearbook of Industry - Poland 2014). Zakład Wydawnictw Statystycznych, Warszawa 26. GUS [2015]: Produkcja Wyrobów Przemysłowych w 2014 r. (Production of Industrial Products in 2014 r.). Zakład Wydawnictw Statystycznych, Warszawa 27. OLKOWICZ M., The portfolio management as support for the development of new products in the furniture industry - part 1. Intercathedra, No. 29/2, 2013, pp. 60 – 68. 28. WIĘCKOWSKA M., Structural changes of furniture industry entities in Poland according to the Regon Register in the years 2009 – 2014. Intercathedra, No. 30/3, 2014, pp. 96 – 102.

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Streszczenie: Potencjał produkcyjny rynku meblarskiego w Polsce. W artykule zaprezentowano analizy porównawcze dotyczące potencjału produkcyjnego rynku meblarskiego i przetwórstwa przemysłowego, do którego zaliczane jest meblarstwo. W tym celu posłużono się wybranymi wskaźnikami ekonomiczno-produkcyjnymi, tj.: produkcja sprzedana, przeciętny poziom zatrudnienia, dynamika wydajności mierzonej produkcją sprzedaną na 1 zatrudnionego. Ponadto zaprezentowano tendencje zmian w produkcji wyrobów przemysłu meblarskiego. Zakres czasowy badań przyjęto na lata 2009-2014.

Słowa kluczowe: przetwórstwo przemysłowe, branża meblarska, produkcja sprzedana, poziom zatrudnienia, wydajność produkcji

Corresponding author:

Magdalena WIĘCKOWSKA ([email protected]), Faculty of Forestry in Hajnówka, Bialystok University of Technology, Bialystok, Poland; Emilia GRZEGORZEWSKA ([email protected]), Department of Technology and Entrepreneurship in Wood Industry, Faculty of Wood Technology, Warsaw University of Life Sciences – SGGW, Warsaw, Poland

255 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 256-261 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Dynamic burnishing of wood

GRZEGORZ WIELOCH University of Life Science, SGGW, Warsaw, Poland, ZDZISŁAW WARMUZ Domus, Katowice, Poland

Abstract: „Dynamic burnishing of wood” The subject of the article is dynamic burnishing of Wood, which is used in a different way than previously because it is used to surface structuring. Described technology is a method using burnishing of wood outer layer via multiplied impact by elements hanged on head which rotations result in their movement with simultaneous transmitting kinetic energy. Kinetic energy is changed into energy of plastic deformation of outer layer which is structured. A head with hammers and head driving device were used in the experiment.

Keywords: wood, dynamic burnishing, structuring head

INTRODUCTION

Burnishing is one of the methods of finishing treatment during grinding and machining . During burnishing a tool and treated object perform movements relative to each other depending on the type of burnishing. Burnishing has boomed as technology enabling improvement in surface smoothness with simultaneous enforcement of outer layer of treated objects. Static, turning or glide burnishing were studiem among others by: [Dranovskij 1963], [Fidyk 1972], [Mamet 1974], [Nawrat 1978, 1979], [Wieloch 1979, 1985, 2004, 2012]. Efforts to apply above mentioned forms of burnishing weren`t spread despite promising results. The only type of burnishing which was widely used in e industry was rolling. It was used to smoothing particle boards and MDF boards.

DYNAMIC BURNISHING

Another type of burnishing which at present is in the range of interest, is dynamic burnishing, used for surface structuring. The technology of such structuring consists of burnishing of wood outer layer via multiplied impact by elements hanged on head which rotations result in their movement with simultaneous transmitting kinetic energy. Stored energy in burnishing elements (steel or glass balls, steel shot, rings and so on) is passed to machined surface. Kinetic energy is changed into energy of plastic deformation of outer layer. The characteristic feature of this type of burnishing distinguishing it from static burnishing is variability of strength with which burnishing elements impact the machined object. The effects of burnishing depend not only from geometry of burnishing element and energy of impact on machined object but also from the number of strikes per unit area and topography of these strikes, [Zaleski 2005]. This is especially important for early and late wood processing [Kiepuszewski, Cegielski 1966]..

DUST-FREE STRUCTURING OF WOOD

Described below method of wood surface structuring is further developing innovative

256 technology. At present it is under investigation but in this early stage we can safely say that the prognosis for it are promising. It involves the formation of local plastic deformation of the surface layer of the object that exceeds the value of the plastic tension of the machined object. This is the result of the contact interaction of hard and smooth tool (of different shape e.g. ball, roller) with machined surface. It is important that the burnishing processing is not a shaping processing as the shape of the object has already been formed during pre-operations. Plastic deformations are caused by the alignment of forces causing surface pressures in excess the value of the yield stress of the machined object. They cause besides movement of surface roughness also squeeze in surface layer of machined object. The effect of the movement of the surface roughness is its reduction on machined surface while the effect of squeeze essential change in properties of the surface layer of machined object.Wood surface structuring means giving it texture of wood, which looks like used for a long time via highlighting annual rings of wood. Sometimes it means marking on the surface other elements e.g. traces after tools treatment, imitation of wear because of use or pretending traces of insects reset. In the case of structuring three methods are widely used: sanding, brushing and dressing is based on [Kiepuszewski, Cegielski 1966, Wieloch 2004, Zaleski 2005]. Sanding is based on application of a sand stream which when thrown with high energy hits the surface and pulls out its fragment. In the case of brushing metal or plastic brushes rotating hit wood surface pulling out softer fragments of wood. Disadvantages of above described technologies is much dust created during structuring and torn apart cell structure

of wood surface. In the case of dressing necessity of accomplishment of adequate knife.

Fig. 1. Wood after dust-free structuring of wood

STRUCTURING PROCESS

During the experiment a grinder produced by Prochera type KSB-2 with stepless regulation of spindle was used. Instead of grinding head a burnishing head was used. The head was equipped in patented machining elements performed according to unique

257 technology. In this case chains finished with rings from stainless steel wire were used. The chains were threaded on sprig pilots. It resulted in easier regulation and even distribution on the whole width of the head. Fixing springs to head enabled obtaining good distribution of hitting [4] whole structured surface.

STRUCTURING HEAD - BASIC TECHNICAL DATA Positioning of head over transporter- maximal thickness of machined element - 80 mm Outer diameter of ring dz - 6,35 mm Diameter of structuring head D – 220 mm Speed of head –regulated stepless by frequency converter 150 – 2000 obr/min. Feed speed - regulated stepless u = 1 – 10 m/min. Quantity of spring pilots 32 The length of spring pilots 205 mm Drive motor power of head1,5 kW Drive motor power feed 0,25 kW

Material feed took place on transport belt. Lack of need to fix work-pieces during structuring indicates that during this process minimal forces are induced. Elements which contact the surface do not brush it like it happens during brushing but hit it. [Fig. 2 and 3].

Fig.2 and 3. Grinder produced by Procher type KSB-2

258

Fig.4. Head for structuring; one can notice burnishing elements moved away from head by centrifugal force.

Grinder

Spring pilot

Hammers

Structured wood

Fig.5. Construction of dynamically

burnishing head with hammers retrorsed under the action of centrifugal force- 300 rot/min

259

Fig.6. Not working head. One can notice dangling hammers from pilots.

Elements contacting surface do not brush it, as it happens during brushing, but hit it. [Fig.5]. Thereby the surface is hardened getting unique texture resulting of anatomical structure of wood. In this technological process the surface is grinded and scratch out of smooth material doesn`t take place, whereby to gain final effect later polishing or grinding of surface is not necessary. The technology described above is dustless and because of the fact that softer fragments of wood are indented in wood we obtain not only rustical surface but also its hardening. Differentiation of indents is strictly connected with annual increase of wood which can be observed on Fig. 2.

CONCLUSION

Does the above mean that this method has no drawbacks? We aren`t sure yet. It is widely known that wood after humidification comes back to its former original position and often seems to swells. Experiments in this field are being continued and we hope that they will give response to the signaled problems.

REFERENCES 1. DRANOVSKIJ M.S., 1963: Issledovanije i razrabotka oborudovanja dlja termoprokata dreviesiny. Lesnaja Promyszlennost. Moskva. 2. FIDYK S., 1972: Metoda ujednolicenia grubości i wygładzenia powierzchni drewna i tworzyw drzewnych. Prace Instytutu Technologii Drewna. Poznań nr.19, 1/2, 61/62. 3. KIEPUSZEWSKI S., CEGIELSKI S.,1966: Podstawy technologiczne kulowania obrotowego i badanie ścieralności powierzchni kulowanej. Prace Poznańskiego Towarzystwa Przyjaciół Nauk. 4. MAMET A.,1974: Wpływ parametrów powierzchniowej obróbki przez ślizgowe nagniatanie na chropowatość powierzchni drewna. Maszyn. Pracy doktorskiej.

260 5. NAWRAT G.,1978: Uszlachetnianie zaokleino przemysłowych. Przemysł Drzewny nr 9. 6. NAWRAT G. ,1979: Uszlachetnianie oklein wybranych gatunków drewna. a. Przemysł Drzewny nr 2. 7. Policzkowanie drewna – rustykalne powierzchnie.,2016. Meble. Materiały i akcesoria. Nr 8. 8. WIELOCH G., KRUSZEWSKI M.,1979: Badania możliwości utwardzania warstwy wierzchniej na drodze nagniatania udarowego. Materiały V Sympozjum Naukowo - Technicznego Poznań – Zielonka. 9. WIELOCH G., 1979: Badania możliwości utwardzania warstwy wierzchniej na drodze nagniatania udarowego. Materiały V Sympozjum Naukowo -Technicznego Poznań – Zielonka 10. WIELOCH G., 1985: Stan struktury geometrycznej powierzchni drewna po nagniataniu udarowym. Roczniki AR w Poznaniu 162, Techologia drewna, nr 18. 11. WIELOCH G.., 2004: Studia nad stanem struktury geometrycznej powierzchni drewna i tworzyw drzewnych po walcowaniu wygładzającym. Roczniki AR w Poznaniu, Rozprawy naukowe. z.353. 12. WIELOCH G., PORANKIEWICZ B., MOSTOWSKI R., 2010: Wykorzystanie skrawania do strukturyzacji powierzchni drewna. Szkoła Obróbki Skrawaniem. „Obróbka Skrawaniem – współczesne problemy. Politechnika Łódzka tom.4 13. WIELOCH G., ZBIEĆ M., 2012: 14. ZALESKI K., 2005: Urządzenie do fizycznego modelowania procesu nagniatania dynamicznego rozproszonego. Przegląd mechaniczny, rok wyd..LXIV, nr 9S. 15. www. prochera com.pl (dostęp maj 2015)

Streszczenie: Bezpyłowa strukturyzacja drewna (BSD). Przedstawiona metoda strukturyzacji powierzchni drewna nazwana „policzkowaniem” jest metodą w fazie badań, ale można śmiało powiedzieć, że rokowania dla niej są obiecujące. Polega ona na wytworzeniu miejscowego odkształcenia plastycznego w warstwie wierzchniej przedmiotu przekraczającego wartość naprężenia uplastyczniającego materiały, Jest to skutek stykowego współdziałania twardego i gładkiego narzędzia o kształcie krążka, z powierzchnią obrabianą. Powodują one oprócz przemieszczania nierówności, także zgniot w warstwie wierzchniej obrabianego przedmiotu. Strukturyzacja powierzchni drewna to nadaniu jej wyglądu starego drewna poprzez uwypuklenie rysunku słojów rocznych drewna. Poprzez głębsze wciśnięcie drewna wczesnego aniżeli drewna późnego Przedstawiono skonstruowaną głowicę obtłukującą opartą o zbiór luźnych bijaków.

Corresponding authors:

GRZEGORZ WIELOCH: University of Life Science, SGGW, ul.Nowoursynowska 159, Warsaw, Poland, [email protected] ZDZISŁAW WARMUZ: “Domus”, Katowice, Poland, [email protected]

261 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 262-270 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

An assessment of the technological parameters of processing medium-size raw material for industrial use

WIERUSZEWSKI MAREK, MIRSKI RADOSŁAW Department of Wood-based Materials, Faculty of Wood Technology, University of Life Sciences in Poznan

Abstract: An assessment of the technological parameters of processing medium-size raw material for industrial use. The shortage of large-size raw material and its high prices are the reason for searching materials with lower cost of processing. It is possible to use some sorts of medium-size raw material and obtain parameters that meet the requirements of industry. The research shows that some sorts of medium-size raw material can be successfully used instead large-size as their parameters meet the requirements of industry. Wood for industrial use, after qualitative sorting allows to achieve a satisfactory level of performance in relation to indicators of processing large-size sawmill wood

Keywords: sawmilling, wood medium sized, efficiency

INTRODUCTION Due to the current age structure and species composition of forests large amounts of wood from young trees are used for economic purposes. This wood has different characteristics than the wood from mature trees (Leśnictwo 2015). However, regardless of the rules of wood material acquisition and classification, the age and habitat of trees are decisive to wood properties (Spława-Neyman 1998, Andrzejczyk, Drozdowski 2007). In Poland pine is the predominant species as its total share in tree stands amounts to about 67% (Leśnictwo 2015). In lowlands there is a vast majority of pine-trees among other species. The share of pine trees in individual nature and forest regions looks as follows: Greater Poland and Pomerania (Region III) – over 87%, Lesser Poland (Region VI) – over 77%, Masovia and Podlasie (Region IV) – over 73%, Masuria and Podlasie (Region II) and the Baltic (Region I) – about 63-65%. Wood is a natural raw material that can be processed within a wide range of its applications (Krzysik 1974, Kokociński 2005). The main goal of the primary breakdown industry is to produce sawn material in the form of edged and non-edged timber, woodwork, elements for the furniture industry,semi-finished products and otherproducts made of wood. (Buchholz 1990, Hruzik et al. 2005, Hruzik 2006). The increasing demand for wood materials and products and simultaneously, the decreasing supply of large-size sawmill wood is the problem which should be solved by extension of the raw material base through wider use of thinner assortments, including medium-size wood (Fig. 1), which makes about 46% of the raw material acquired. Rational raw material processing as well as constant improvement and introduction of new technologies are necessary to ensure the cost-effectiveness of production and the desired amount of products. The efficiency of use of medium-size raw material for mechanical processing (S2B) is estimated at 45-60%. It results from considerable influence of the assortments of products (Buchholz 1990, Hruzik 2006, Ratajczak 2011).

262 Hard firewood, Small-size 5% wood, 5% Other, 2.20% Medium-size Medium-size hardwood, 11% softwood, 35% Large-size hardwood, 7%

Soft firewood, 4% Large-size softwood, 33%

Figure 1. The percentage of wood acquired, according to assortments in the National Forest Holding ‘State Forests’ (Leśnictwo 2015)

According to the Polish Standard PN–91/D–95018 and Technical Conditions concerning medium-size wood (Directive 33 and 34 issued by the Director of the National Forest Holding ‘State Forests’ on 17 April 2012) the large-size utility wood class S2 is divided into subgroup S2AC for energy purposes and subgroup S2AP for industrial purposes, with a considerable share of permissible curvature (12cm/m) and specific quality parameters. Both of these subgroups are defined as pile wood, but subgroup S2AP is called industrial wood, which is also used for mechanical purposes. In spite of the development of technology, production of different plasticsand competition between materials, wood is becoming an increasingly valuable material due to its natural origin, unique properties and peculiar beauty. Owing tothe development of technology and innovative solutions there are more possibilities of wood processing and application. The importance of wood as a raw material is proved by the fact that whenever possible, it is replaced by other materials and due to the growing deficit of wood there are attempts to rationalise its processing (Krzysik 1974, Ratajczak 2011, Kozakiewicz, Krzosek 2013).

AIM AND RANGE OF STUDY The study is an analysis of the possibilities to use S2AP softwood assortments in primary breakdown and an attempt to determine the influence of the dimensional parameters of theseassortments described with sawing indexes. The results of investigations for selected medium-size pinewood batches were sorted in order to identify dimensional groups according to diameters and to determine sawing indexes for semi-finished products for mechanical production. The study involved investigations aimed at specifying how useful this form of medium-size pinewood material was for primary processing to acquire sawn materials.

MEASUREMENT METHODS 726 short medium-size logs (72%) with reduced curvature limited to 3 cm/m (twice as much as the maximum permissiblecurvature in class S2B) were sorted out of the batch of

263 1,000 pieces of medium-size S2AP pinewood. Each piece was measured. The usefulness of the short medium-size logs for processing was also assessed on the basis of the thinner (upper) end diameter (dg) and length (l). The following dimensional groups were identified for the upper diameter scales,without bark, at 4-cm intervals: I. 9-12cm, II. 13-16cm, III. 17-20cm, IV. 21-24cm, V. 25-28cm. Individual dimensional groups of medium-size material were sawn into 44-mm thick lath elements and 16-mm thick plank assortments, which were edged and shortened to the dimensions listed in Table 1.

Table 1.Aquantitative comparison of individual groups of sawn assortments Thickness Assortment [mm] Width [mm] Length [mm] [mm] Lath 44 73 610 Plank 1210 x 75 16 75 1210 Plank 1210 x 105 16 105 1210 Plank 960 x 75 16 75 960 Plank 960 x 105 16 105 960 Plank 800 x 75 16 75 800

The sawing indexes for individual dimensional groups were calculated according to the following formula:

∑ = ∗ 100 [%] where: 3 ∑Vt – total volume of timber [m ], 3 Vk – the volume of the short medium-size logs from which timber was made [m ].

RESULTS OF STUDY Analysis of diameters The measurements and their analysis revealed that short medium-size logs with the thinner end diameter of 12 cm had the greatest share (18%) in a randomly selected batch of medium-size pinewood S2AP with a nominal length of 2.4 m. The next most numerous groups consisted of the material with diameters of 13cm (14%) and 11cm (12%).Short medium-size log diameter groups II and I were predominant – they had a total quantitative share of 74%. Short medium-size logs with diameters of 10-20 cm were the predominant assortment group of medium-size wood as they amounted to 91% of the total quantity of the S2AP material under analysis (Fig. 2).

264 50

39.8 40 34.2

20 17.4

10 5.4 3.2 participation [%] participation 0 9-12 13-16 17-20 21-24 25-28 diameter [cm] Figure 2. The percentage of individualdimensional groups in the S2AP batch

According to the Polish Standard PN – 91/D – 95018 concerning medium-size wood material, the wood in class S2A must have a maximum lower diameter of 24 cm. As can be seen in Fig. 3, there were some pieces of wood with larger diameters. The calculation of the average taper of 0.7cm/m at the lower end thickness ofthe short medium-size logs showed that about 7% of round wood in the batch under analysiscould be classified as short large-size logs.

short large- size logs

short medium- size logs

0 20 40 60 80 100

participation [%]

Figure 3. The percentage of short medium-size logs and short large-size logsin the batch

Analysis of material length The analysis of the dimensions of the short medium-size and large-size logs under study showed that the vast majority of pieces of wood was 2.51 m long. The next most numerous groups consisted of short medium-size logs, which were 2.50m and 2.52m long

265 (Fig. 20). The vast majority of short medium-size logs was 2.47-2.55 m long, which made 92% of the quantity of the batch under study (Fig. 4). 25.00 19.80 20.00 19.00 15.80 15.00 10.80 10.00 7.20 7.00 4.20 participation [%] participation 4.60 5.00 4.00 1.20 1.90 0.00 236 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260

length scale [cm]

Figure 4. The quantitative share of material in the length scale

According to the Polish Standard PN – 91/D – 95018and Technical Conditions concerning medium-size wood material(Directive 33 and 34 issued by the Director of the National Forest Holding ‘State Forests’), the permissible deviations for S2AP wood within the lengths of 2-7 mcannot exceed +/- 0.05 m. As results from the measurements, the maximum permissible length ofshort medium-size logs from the batch with the nominal length of 2.4 m is 2.45 m. The measurements revealed that as much as 489 pieces of round wood, i.e. 97.8% of the total batch exceeded this limit.

Analysis of the volume of S2AP round wood for industrial production The total volume of the whole S2AP group under study was calculated on the basis of dimensional measurements. The volumes of dimensional groups II and III were predominant (Table 2).

Table 2. The volumes of individual dimensional groups in class S2A Percentage Dimensional group Diameter range [cm] [%] I 9-12 19.46 II 13-16 34.74 III 17-20 24.95 IV 21-24 11.54 V 25-28 9.31

The values in Fig. 5 and 6show that volumes of short medium-size logs were predominant. The volume of short large-size logs amounted to about 17%.

266 short large-size logs

short medium- size logs

0 20 40 60 80 100 participation [%]

Figure 5. The percentage of volume of short large-size logs in the S2A batch

The actual volume of the research material was measured in order to determine the influence of dimensional parameters on the batch volume. The result was theoretically compared with the actual volume of the whole S2AP batch and it revealed the difference (surplus) of about 5% of the volume of the batch under study (Fig. 25).

Volume - Addition

Volume - ordered

0 20 40 60 80 100

participation [%]

Figure 6. The share of additional wood volume in the wood volume

Analysis of the influence of dimensional groups in sawing indexes The average index of class S2AP efficiency measured in the sawing procedure of selected assortments for the production of transport pallets amounted to about 50.29%. After the verification of sawing in the thickness groups of medium-size wood, the material efficiencies shown in Fig. 7 were compared. The highest efficiency (about 54%) was noted in dimensional group II (13-16cm), whereas the lowest efficiency (about 46%) was observed in

267 group I (9-12cm). The maximum efficiency in thickness group II amounted to about 3% of the average efficiency for the whole S2B batch. 56

46 Efficiency [%] Efficiency 44

42 9-12 13-16 17-20 21-24 25-28 mediana

Diameter [cm]

Figure 7. The sawing indexes for S2AP medium-size wood

Fig. 8 shows that the total volume of the elements acquired from the research batch was 13.144m3. Laths had the greatest volume (60%). Assortments of planks had the lowest share (40%).

20 products [%] products Share in structure of in structure Share 0 Lath Plank Plank Plank Plank Plank 1200x75 1200x105 960x75 960x105 800x75

Figure 8. The percentage of volume of semi-finished products

SUMMARY Assortments with square sections (laths) predominated in the structure of sawn products. Their share amounted to about 60%. In the group of side elements there were full- size and short-size planks to be edged at a scale of 2 cm. Among the five thickness groups in quality class S2AP, the highest efficiency was observed in dimensional group II 13-16cm) – about 54%. It is noteworthy that among all the dimensional groups the lowest efficiency was

268 noted in thickness group I (46.30%). This situation shows that the permissible curvature in medium-size wood assortments and variation of diameters within a particular thickness group have considerable influence on sawing results. The results confirm the influence of dimensions in the thickness group. In quality class S2APthere was 12% of 10-cmshort medium-size logs and 35.09% of 11-cmshort medium-size logs in thickness group I. Thus, we can conclude that even a minimal increase in the share of material with thicker assortments results in higher efficiency.

CONCLUSIONS The research was conducted on the sample batch under industrial conditions. It showed the influence of selected dimensional groups of short medium-size softwood logs on sawing indexes. The following conclusions can be formulated: 1. The dimensional group with the upper end diameter of 13-16 cm was the most numerous and it was characterised by the highest efficiency. Efficiency can be increased by appropriate material sorting. 2. S2AP wood came from the batch which underwent preliminary sorting to improve its quality (reduce the curvature). The result showed that there were differences between the experimental processing efficiencies and average values noted in the sawing long- size wood processed in sawmills. 3. The sorting of the research material into dimensional groups revealed considerable differences in the values of sawing indexes between individual dimensional groups. It shows that it is justified to sort medium-size wood in order to increase the processing efficiency. 4. The medium-size pinewood material consisted of only short medium-size logs with the maximum thicker end diameter of 24 cm. The analysis of diameters showed that there was a considerable group ofshort large-size logs, which were delivered in the group of medium-size stacked wood. 5. There are considerable surpluses in the length of assortments acquired. They increase the actual volume of wood. The excess of materialis eliminated by reducing the length of assortments.

REFERENCES 1. Andrzejczyk T., Drozdowski St. 2007: Impact of site conditions on the structure and volume of spruce-pine stands in the Augustowska Primeval Forest. SYLWAN n. 151 (1):30-40, 2. Buchholz J. 1990. Technologia tartacznictwa, Skrypt AR w Poznaniu. 3. GUS 2015: Leśnictwo 2015. 4. Hruzik G.J. 2006: Zużycie surowca i materiałów drzewnych w wyrobach przemysłu tartacznego. Drewno-Wood 2006, vol.49, nr 175, s.25-44.

269 5. Hruzik G.J., Gotych W., Wieruszewski M. 2005: Efektywność produkcji przykładowych wyrobów tartacznych na rynek krajowy i europejski. Przemysł Drzewny nr 5, s.18-21. 6. Krzysik F. 1974. Nauka o drewnie, PWN Warszawa 1974. 7. Puchniarski T.H. 2008. Sosna zwyczajna Hodowla i ochrona. PWRiL Warszawa 2008. 8. Spława-Neyman S. 1998. Prace Instytutu Technologii Drewna. Średniowymiarowy surowiec sosnowy. 42 (3-4): 37-59. 9. Kozakiewicz P. , Krzosek S. 2013: Inżynieria materiałów drzewnych. Wydawca: Wydawnictwo SGGW 2013 10. Kokocinski W. 2005:Anatomia drewna. Wydawca: Prodruk 2005, Wydanie II. 11. Ratajczak E., Bidzińska G., Szostak A. 2011: Foresight w drzewnictwie Polska 2020. Obszar badawczy: Ekonomika drzewnictwa. Wydawca Instytut Technologii Drewna Poznań.

Streszczenie: Ocena parametrów technologicznych przerobu surowca średniowymiarowego do zastosowania przemysłowego. Niedobór surowca wielkowymiarowego i jego wysoka cena wymuszają poszukiwanie surowca o niższych kosztach przetworzenia. Co raz częściej w przerobach mechanicznych wykorzystuje się sortymenty w postaci drewna średniowymiarowego jednakże o parametrach spełniających wymagania dla materiałów tartych. W efekcie sortowania jakościowego surowca średniowymiarowego uzyskuje się sortymenty o zbliżonych wskaźnikach wydajnościowych do przerobu drewna wielkowymiarowego.

Corresponding author:

Wieruszewski Marek Mirski Radosław Department of Wood-based Materials University of Life Sciences in Poznan 60-627 Poznań Ul. Wojska Polskiego 38/42 E-mail: [email protected] [email protected] Tel./fax (061)8487419

270 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 271-279 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The technological parameters of medium-size raw material for mechanical processing WIERUSZEWSKI MAREK, DERKOWSKI ADAM Department of Wood-based Materials, Faculty of Wood Technology, University of Life Sciences in Poznan

Abstract: The technological parameters of medium-size raw material for mechanical processing. It is possible to use some sorts of medium-size raw material and obtain parameters that meet the requirements for obtaining sawnwood. The research confirm that sorts of medium-size raw material can be successfully used instead large- size. Wood medium-size , after sorting allows to achieve a satisfactory level of performance in relation to indicators of processing large-size sawmill wood.

Keywords:, mechanical processing, wood medium sized, efficiency

INTRODUCTION At present the demand for sawn materials and wooden products is not satisfied in Poland due to insufficient amounts of wood acquired. Therefore, it is necessary to use available materials rationally. The material efficiency of processing is a basic technological indicator characterising the current production potential of sawmills. It shows the scale of using raw material in wood processing. This indicator can be directly correlated with the qualitative and dimensional selection of logs as well as with the demand for material adjusted to the specificity of manufacturing wood products (Hruzik et al. 2004, Hruzik 2006). In order to rationalise the production of sawn materials it is necessary to limit the production of general use timber. It should be gradually replaced by semi-finished products and highly processed timber for specific purposes. Higher subsidies for the sawmilling industry to prefabricate timberfor specific purposes will enable better use of wood (Korczewski, Krzysik, Szmit 1970, Ratajczak 2011, Kozakiewicz, Krzosek 2013). Medium-size wood is sometimes considered a lower quality product. In Germany this dimensional category is calledIndustrieholz – industrial wood or Schwachholz–poor wood. Due to the attractive price of medium-size wood it is possible to achieve good economic efficiency from its processing. The price is the factor that makes timber manufacturers use medium-size wood whenever high quality products are not required. The diameter range of 7 cm at the upper end and 24 cm at thelower end causes limitations and affects the possibilities of using this material (Giefing 2004). According to Polish Standard PN–91/D–95018 and the Technical Conditions concerning medium-size wood turnover for industrial and energy purposes (Directive No. 33 and 34 issued by the Director of the National Forest Holding ‘State Forests’ on 17 April 2012), there are four main groups differing in quality and dimensions. In the group of utility assortments S2 we can distinguish subgroup S2B, which is characterised by lesser curvature of wood for mechanical purposes. This group provides basic raw material for the production of flat pallets. The production of packages, including pallet production is a branch of the wood industry. A flat pallet is a wooden product with a wooden board, which is used for carrying a load for anunspecified period of time (during transport and storage). The construction of a pallet must guarantee the possibility to move it by means of fork-lift trucks. Pallets are classified as the containers whose application enables mechanised loading and unloading, facilitatestrade in goods, cuts costs and provides betterhealth and safety conditions during transport and storage of goods (Milewski 1980).

271 Depending on the construction, pallets can be classified (Milewski 1980, PN-EN ISO 445:2013-06) according to the following categories: • load-bearing deckboard: single deckboardpallets, double deckboardpalletsand reversible double deckboard pallets, • the number of entries: two-entrypallets and four-entry pallets, • the presence of wings: pallets with wings and wingless pallets. Pallet dimensions are standardised in Europe to facilitate international transport and avoid logistic problems. Euro-pallets marked with the EUR symbol are usually used. The four most common types of EUR pallets are as follows (www.paletycentrum.pl): • EUR - 800 x 1200 mm, • EUR 2 - 1200 x 1000 mm, • EUR 3 - 1000 x 1200 mm, • EUR 6 - 800 x 600 mm. In 2006 Poland started manufacturing EUR pallets. Since that time the annual production has been increasing every year. In 2014 more than 20 million EPAL pallets were produced in Poland (Fig. 1). Poland is a significant manufacturer in the pallet industry, which is still developing rapidly.

80 70 60 50 40 30 20 10 0

quantity [millionquantity units] 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

World Year Poland

Figure 1. The production of EPAL pallets in Poland vs global production (Przemysł Drzewny 2015)

Appropriate quality of wooden elements and manufacturing precision are decisive factors to the durability and use value of pallets. There are high quality requirements for wooden pallets to be used in Europe. There are differentquality requirements for softwood and hardwood and different standards concerning the use of pallets identified as EUR ones according to UIC435-2card and ECEREPAL(ISPM) pallet assessment cards (Milewski 1980, PN-M-78224, PN-EN 12249:2002).

AIM AND RANGE OF STUDY The aim of the study was an analysis of the influence of dimensional parameters of medium size round softwood assortments S2B (the thinner end diameter of 5 cm and thethicker end diameter of 24 cm)on sawing indicators. The sawing results for selected batches of medium sizepinewood were verified. Dimensional groups were identified according to the diameter. Sawing indicators for manufacturing semi-finished pallet products

272 were identified. The aim of the study was to show the scale of differences in the efficiency of processing individual dimensional groups of medium-size round wood and to verify the significance of these differences.

MEASUREMENT METHODS In order to achieve the aims of the study a batch of 500 pieces of medium-size pinewood was selected and measured. All the pieces were measured. The thinner (upper) end diameter (dg) and thelength (l) were measurable parameters ofmedium-size round wood. The diameters were measured without bark, by means of a measuring tape, at an accuracy of 1 mm. The measurement results were rounded mathematically. The shortest line connecting both fronts of medium-size round wood was measured. Measured pieces were sorted into dimensional groups according to the upper (thinner) end diameter, without bark, at 4-cm intervals: I. 9-12cm, II. 13-16cm, III. 17-20cm, IV. 21-24cm, V. 25-28cm. Individualdimensional groups were sawn into square edge timberand plank assortments (PN-EN 12249:2002) with the dimensions listed in Table 1.

Table 1. A quantitative comparison of individual groups of sawn assortments Assortment [mm] Length [mm] Width [mm] Thickness [mm] Lath 610 44 73 Plank 1210 x 75 1210 75 16 Plank 1210 x 105 1210 105 16 Plank 960 x 75 960 75 16 Plank 960 x 105 960 105 16 Plank 800 x 75 800 75 16

Medium-size pinewood with a nominal length of 2.4 m was the research material.

RESULTS OF STUDY Analysis of diameters In the batch ofS2B medium-size round wood under study there was the greatest number of 13-cm thickassortments, i.e. about 19% of the batch. The second most numerous group consisted of 12-cm thick pieces – about 18% (Fig. 2).Medium-size round wood pieces with diameters greater than 19 cm were the least numerous. The share of the material with diameters ofless than or equal to 19 cm amounted to 86.4%. The share of medium-size round wood pieces with diameters of 13-16 cm amounted to 49% - it was the predominant dimensional group in the S2B batch under study (Fig. 3).

273 25.0

20.0

15.0

10.0 Part[%]

5.0

0.0 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Diameter [cm]

Figure 2. The number of round wood with individualdiameters in the S2B class (compiled by the author)

60 49 50

30 22 20 17 Part [%] Part 10 6 6

0 9-12 13-16 17-20 21-24 25-28

Diameter [cm]

Figure 3. The percentage of individualdimensional groups in the S2B class

According to the normative verification PN – 91/D – 95018, there was as much as 8.8% of short large-size round wood in the group with the thinner end diameter greater than or equal to 22 cm (Fig. 4).

274 short medium-size logs 8.8% short large-size logs

91.2%

Figure 4. The percentage of short medium-size logs and short large-size log sin the batch

Analysis of material length Measurements of the length of the S2B medium-size material revealed that the dimension of 2.52 m was predominant as it amounted to 29% of all pieces in the batch.The most numerous group consisted of short medium-size logs with lengths ranging from 2.50 m to 2.56 m (88%) (Fig. 5). There were no dimensional deficits in the 2.4 m length group, with a deviation of +/-0.05m. The number of pieces which exceeded the normative surplus amounted to 97% of the batch quantity.

35.0 30.0 25.0 20.0 15.0 Part[%] 10.0 5.0 0.0 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262

length [cm]

Figure 5. The quantitative share of material within the length range of 2.43-2.62 m (compiled by the author)

Analysis of the volume of S2B round wood The total volume of the selected thickness groups in the batch of S2B medium size wood amounted to 28.37m3 (Table 3).

275 Table 3. The volumes of individual dimensional groups in class S2B Thickness group Diameter range [cm] Volume [m3] Share [%] I 9-12 3.51 12.38% II 13-16 11.02 38.83% III 17-20 6.11 21.55% IV 21-24 3.21 11.31% V 25-28 4.52 15.92% Total 28.37

45.0 40.0 35.0 30.0 25.0

Part [%] Part 20.0 15.0 10.0 5.0 0.0 9-12 13-16 17-20 21-24 25-28

Diameter [cm]

Figure 6. The volume of individual dimensional groups

Charts 6 show the share of predominant thickness groups, whereshort medium-size logs in groups II (39%) and III (22%) were the most numerous.

21.5%

short medium-size logs short large-size logs

78.5%

Figure 7. The percentage of the volume of short large-size logs in the S2B batch

276 The share of short large-size logs in the total volume of the S2B class amounted to 21% (Fig. 7), i.e. 6.10m3 out of 28.37m3in the batch of medium-size material under study. When the assumed volume of wood at a nominal length of 2.4 m and the actual diameters ofshort medium-size logs and selected short large-size logs were compared with the actual volume of the total batch of 500 pieces of S2B wood, it turned out that there was a surplus of 1.511 m3of wood, i.e. about 5% (Fig. 8).

Volume - Addition

Volume - Ordered

0.0% 20.0% 40.0% 60.0% 80.0% 100.0%

participation [%]

Figure 8. The percentage of additional wood volume

Analysis of the influence of dimensional groups on sawing indexes. Efficiency There was the average efficiency of about 51% in the sawing of the medium-size material in the batch of S2B wood under study into semi-finished pallet products (Fig. 9). The highest efficiency (about 54%) was noted in the sawing of wood in thickness group I (9- 12cm). The efficiency of processingshort medium-size logs andshort large-size logs in the other thickness groups was close to 51%.

51 Efficiency [%] Efficiency 50

49 9-12 13-16 17-20 21-24 25-28 mediana

Diameter [cm]

Figure 9. The sawing indicators of S2B assortments

277 The largest groups of semi-finished products werelaths (65%) and planks (35%) (Fig. 10)

20 products [%] products Share in structure of structure in Share 0 Lath Plank Plank Plank Plank Plank 1200x75 1200x105 960x75 960x105 800x75

Figure 10. The percentage of the volume of individual semi-finished products after sawing the S2B batch

CONCLUSIONS The study on the influence of selected dimensional groups of softwood logs on sawing indicators was conducted on a batch of wood under industrial conditions. The observations let us draw thefollowing conclusions: 1. Thickness group II with an upper end diameter range of 13-16 cm was the most numerous group in the batches under study. It was also characterised by the greatest volume.As a result, there was higher efficiency when an appropriate coupling of saws was applied. 2. The sorting of material which is to be sawn into thickness groups causes differencesin sawing indicators in individual dimensional groups. 3. Medium size pinewood material is characterised by considerable variation of thickness. There was also a considerable share of short large-size round wood (5%) purchased for the price of medium-size wood applied in the study. 4. There was inaccuracy in acquiring appropriate lengths of raw material. There was a high surplus in length (for about 97% of pieces). It increased the actual weight of wood, but had negative influence on possible sorting processes. 5. S2B wood came from the batch which underwent sorting to dimension. Were differences between the processing efficiencies and average values noted in the sawing of large-size wood processed in sawmills..

REFERENCES 1. Giefing D. F. 2004: Postępy techniki w leśnictwie. Wykorzystanie drewna gorszej jakości w wybranych krajach Unii Europejskiej. 87 pp.7-10. 2. Hruzik G., Gotycz W., Marciniak A., Szyszka B. (2004): Zastosowanie metod numerycznych do optymalizacji wtórnego przerobu drewna. Przemysł Drzewny 3, 26–28. 3. HruzikG.J. 2006: Zużycie surowca i materiałów drzewnych w wyrobach przemysłu tartacznego. Drewno-Wood 2006, vol.49, No. 175, pp.25-44. 4. Korczewski A.O., Krzysik F., Szmit J.M. 1970. Tartacznictwo.

278 5. Kozakiewicz P. , Krzosek S. 2013: Inżynieria materiałów drzewnych. Wydawca: Wydawnictwo SGGW 2013 6. Milewski A. 1980: Materiały i wyroby z drewna, PWE Warsaw. 7. PN-91D-95018: Wood material. Medium-size wood. 8. PN-EN 12249:2002 – Timber for pallets–Permissible deviationsand recommended dimensions 9. PN-EN ISO 8611-3:2012 - Palletsfor materialmanagement -Flat pallets - Part 3: Maximum operating loads 10. PN-M-78201:1989 - Flat load-bearing wooden pallets - Commonrequirements and tests 11. PN-M-78224:1996 –Flat load-bearing double-board wingless wooden pallets with two entries 800 mm x 1200 mm and 1000 mm x 1200 mm 12. Przemysł Drzewny 2015:. Co trzecia europaleta EPAL pochodzi z Polski. No. 3/2015: 30-31. 13. Ratajczak E., Bidzińska G., Szostak A. 2011: Foresight w drzewnictwie Polska 2020. Obszar badawczy: Ekonomika drzewnictwa. Wydawca Instytut Technologii Drewna Poznań.

Streszczenie: Parametry technologiczne surowca średniowymiarowego do przerobów mechanicznych. Co raz częściej w przerobach mechanicznych wykorzystuje się sortymenty w postaci drewna średniowymiarowego spełniających wymagania dla pozyskania tarcicy. W efekcie sortowania jakościowego surowca średniowymiarowego uzyskuje się poprawę wskaźników wydajnościowych do przerobu drewna wielkowymiarowego. Koszt surowca średniowymiarowego rekompensuje różnicę we wskaźnikach wydajności w odniesieniu do drewna wielkowymiarowego.

Corresponding author:

Wieruszewski Marek Derkowski Adam Department of Wood-based Materials University of Life Sciences in Poznan 60-627 Poznań Ul. Wojska Polskiego 38/42 E-mail: [email protected] [email protected] Tel./fax (061)8487419

279 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 280-290 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

The influence of the quantitative and dimensional structure of roof truss elements on the material sawing efficiency and production efficiency

MAREK WIERUSZEWSKI Department of Wood Materials, Faculty of Wood Technology KATARZYNA MYDLARZ Department of Economics and Organisation of Wood Industry, Faculty of Economics and Social Sciences Poznań University of Life Sciences

Abstract: The Influence of the Quantitative and Dimensional Structure of Roof Truss Elements on the Material Sawing Efficiency and Production Efficiency. Wood is widely applied in the building industry due to its physical properties, strength and considerable durability. It is a basic constructional material for the production of roof trusses. It is also applied as glued laminated timber when there are dimensional limitations to solid wood, resulting from the biological and technological possibilities of processing this material. Traditional constructional solutions are more and more often superseded by the use of glulam. Other arguments that speak in favour of glulam are the ecological aspect, wide availability, easy processing and lower price than the cost of other materials used in roof constructions. The aim of the study is to prove the influence of the quantitative and dimensional structure of roof truss elements on the material sawing efficiency and production efficiency.

Keywords: wooden constructions, roof truss elements,material efficiency,production efficiency

INTRODUCTION

The roof truss construction is a supporting structure. It transfers both the load of the roof and the load resulting from the weatherconditions. According to the standards of PN-EN 388‘Constructional Timber. Strength Classes’, timber with adequate strength parameters is used for constructional elements of roof trusses. According to normative guidelines established by the Polish Committee for Standardisation (PKN), such as Eurocode 5 (PN-EN 1995-1-1: 2010 Eurocode 5: Design of Timber Structures– Part 1-1:General -Common Rules and Rules for Buildings – Part 1-2 General Rules - Structural Fire Design. PN-EN 1995- 2:2007 Eurocode 5: Design of Timber Structures – Part 2: Bridges), the timber used and recommended for roof constructions is constructional timber, whose strength class ranges fromC24 to C35. In Poland it is softwood,usually pinewood – ideally fine-ringed and knotless, due to strength properties. As results from domestic research by Krzosek (2009), the classification of constructional timber by means of visual assessment and with the machine-assisted strength- testing method is also affected by the origin of material. The results of studies on materials from the Greater Poland region prove that there was only about 8% of class KW timber which met the standards of PN-EN 388 and PN-EN 1995 –strength class C35 (C30 for spruce timber). Only about 12% of sawn materials was sorted as strength class C24 – sorting class KS. Thus, the remaining 80% of timber belonged to the worse quality class KG, which corresponds to C20 for pine timber and C18 for spruce timber, with a share of about 34%, or it was classified as waste. Therefore, C24 timber is usually used for roof trusses. Simultaneously, designers assume C30 timber as a starting point for strength calculations. From the point of view of material possibilities, it is particularly important to increase the awareness of problems concerning theacquisition of C30 or higher class timber and encourage the choice of C24 timber and the use of adequate sections of constructional elements.

280 The use of timber for constructional purposes, especially its increasing importance and popularisation,caused the need to achieve normative unification. In consequence, since 2012 there has been an obligation to certify constructional timber which is to be used as material for supporting elements. In order to receive a certificate timber needs to be tested according to the standards of PN-EN 14081-1+A1:2011 ‘Timber constructions. Constructional timber with a rectangular cross-section sorted according to strength. Part 1: General requirements’ and EN 14081-2 + A1: 2013-05 ‘Timber constructions - Constructional timber with a rectangular cross-section sorted according to strength - Part 2: Machine sorting; Additional requirements for initial tests’ or PN-EN 94021:2013 ‘Coniferous constructional timber sorted according to strength-testing methods’. The tests show if a particular element meets the necessary requirements. The visual strength assessment sorting method is a basic method of assessment and classification of timber in Poland. It consists in a sorter looking at each piece of timber and classifying it as a particular strength category. Defects in the anatomical structure, shape defects and processing defects are the basic criteria for classifying timber as a particular category (Dzbeński et all 2005). In order to fully verify the mechanical properties and accelerate the sorting process it is possible to introduce the machine-assisted method. It facilitates verification of raw material without causing any damage. However, machine sorting does not eliminate the visual method. It only supplements it, whereas visual assessment enables one to find errors made by the machine, e.g. sorting the ends of elements tested by bending machines (www.drewno.rsi.org.pl). The possibility to acquire timber in primary processing andto retain specific efficiency indexes, which directly refer to production efficiency, is a significant problem which has not been solved in Poland yet. It is decisive to the availability of constructional material with adequate dimensional and qualitative parameters. This idea was the basis of this study.

AIM AND METHODOLOGY OF STUDY

The aim of the study was to identifythe influence of the quantitative and dimensional structure of roof truss elements sorted according to the visual strength assessment method on the sawing and production efficiency of round wood. In order to achieve the aim of the study it was necessary to conduct the following procedures: • verify the origin of timber and its qualitative andquantitative structure, • identify the values of material sawing efficiency, • analyse the percentage of components of the roof truss structure, • calculate the efficiency of production of constructional elements. In order to achieve the objectives we conducted tests in a selected manufacturing plant. The plant is located in the Greater Poland region and it specialises in sawmill processing and production of constructional elements for roof trusses. Wood is gradually supplied to the plant all year round. In each delivery there are assortments meeting the demand. The material is received and stored in piles resting on joists. Above all, export documents are inspected, the number of pieces of wood,volume of individual pieces (the length anddiameter at half-length, type of wood , quality and identification number). After inspection wood is manipulated and cut into round wood assortments. At the next stage qualitative and dimensional parameters of wood are adjusted to dimensional cross-sections of acquired constructional materials. As a result of sawing, we acquire sawn materials, which are subject to strength classification. They need to be visually or machine-sorted for their technical properties according to standards PN- EN 14081-1 and PN-EN 14081-2. This procedure is decisive to the possible application of the

281 material. Selected elements are dried to a maximum humidity of 20%. As far as requirements for constructional timber are concerned, the humidity should be around 15% ±3 %. According to technical requirements, the next stage involves four-sided planing and impregnation. However, chemical protection is not required for all wooden elements. According to the regulations in PN-EN 1995-1-2:2008 and PN-EN 13501-1+A1:2010 ‘The Fire Classification of ConstructionalProducts and Elements of Buildings – Part 1: Classification According to the Results of Fire Tests’, which are applicable in Poland, fire protection is obligatory for wooden constructional elements in public buildings, whereas biotic protection is optionally applied in private buildings. For safety reasons, supporting elements and stiffeners are mainly impregnated. However, it is not obligatory to impregnate non-supportive wooden parts, which do not have a static function and do not need to keep their dimensions (PN-EN 350-2:2000, Neuhaus 2006). Many constructors do not treat wooden elements with any preservatives. They assume that when timber is appropriately prepared (it is chamber-dried and planed on four sides) and when the construction is correctly designed and assembled, these are sufficient precautions protecting the construction from harmful factors. They often emphasise the ecological aspect of constructional elements, which have been prepared in this way.In view of the growing ecological awareness and applicable environmental trends this method of preparation is advocated especially in Germany and Scandinavia (Mydlarz 2008). In view of the subject of this study it is important to consider the issues of production efficiency and material efficiency. These are key issues, which affect economic aspects and cost-effectiveness. Korczewski, Krzysik, Szmit (1970) reported thatmaterial efficiency enabled assessment of material consumption for a particular product. According to these authors, material efficiency is the ratio between the volumeof obtained products processed to a particular extent orprocessed to a particular extentand characterised by a particular trait to the volumeof products at an earlier stage of processing. The concept of material efficiency comprises quantitative material efficiency (Wi), qualitative material efficiency (Wj) and assortment material efficiency (Wa) (Korczewskiet al. 1970). Quantitative efficiency, i.e. the wood consumption index, is the ratio between the volume of timber produced and the volume of wood sawn to acquire the timber (Rzadkowski 1957). Quantitative efficiency is calculated for logs, sawn materials and semi-finished products. The quantitative efficiency of logs (Wik) is the ratio between the volume of timber produced and the log volume(Vd). Korczewski, Krzysik, Szmit (1970) define qualitativematerial efficiency as a parameter showing the ratio between the volume of products processed to a particular extent and characterised by particular quality and thevolume of productsat an earlier stage of processing. Qualitative efficiency is calculated for logs, sawn materials and other semi-finished products. Achieving high efficiency in the processing of logs in different quality groups depends on the knowledge concerning the location of wood defects in round material and on the influence of these defects on the quality of sawn assortments produced. Thequalitativeefficiency of logs (Wjkg) is calculated by comparing the volume of logs in a particular quality group (Vjk) and the volume of the log in question (Vd):

where: 3 Vjk - the volume of logs in a particular quality group [m ], 3 Vd - the volume of logs to be sawn [m ]. Thequalitativeefficiency of timber (Wjt) which is in a particular quality class or category is calculated according to the following formula:

282 where: 3 Vjt - the volume of timber in a particular quality class [m ], 3 Vk - the volume of logs to be sawn [m ] (Korczewski et al. 1970). The processing of wood material into sawn assortments and timber is strongly influenced by production and market factors. The purchase of wood by business entities is an essential determinant of economic effects. The Department of Mechanical Wood Technology conducted research, which proved that the technological efficiency of wood processing was of fundamental importance to the economic effect (Hruzik et al.2005). The technological efficiency of material processing (Ep) is an index expressed with natural units or percentage. It is defined as a sum of the value of goods (main (constructional) timber and other sawmill and accompanying products) obtained from a particular raw material, which is referred to the cost of purchase of the raw material that is necessary to manufacture these products. ∗ ∗ ∗ ∗ 100 % ∗ where: Vw – the volume of processed products for the domestic and European markets, Cw – unit prices of products, Vz – the volume of chip material, Cz – contractual conversion price of chips, Vo – the volume of waste and sawdust, Co – conversion price of waste and sawdust, Vs – the volume of raw material, Cs – contractual price ofraw material, Tr – the cost of transport of raw material (source: Hruzik et al.2005). When the index is defined in this way, the cost of material for processing and the production assortment are basic assessment criteria. The price of raw material and the costs of its transport have the greatest share in the costs of production of sawn materials. Thus, the production efficiency is strongly affected by the current ratio between the price of product and the price of raw material. Recently increasing prices of domestic wood havecontributed to fluctuations in the sawmill production efficiency, whichhave caused negative consequences in the sawmill branch. Simultaneously, it is also noteworthy that the efficiency is also influenced by the exchange rate between the zloty and euro. Above all, it is important for the companies which export and import wood and wooden products. The economic stability of companies is threatened by differences in exchange rates, which directly translate into companies’ profitability and financial liquidity (Lis, Mydlarz 2008).

RESULTS

During the qualitative and quantitative analysis of high-volume sawmill pinewood we selected batches of 647.37 m3of raw material in a random qualitative and dimensional order. Figure 1 show the percentage of the weight of high-volume wood in individual quality groups. As results from the data presented above, class WC0 in the second class of thickness is the predominant quality group in raw material processing. There was also a considerable share in the processing of material of the first class of thickness. However, the system of purchasing wood for the company is not equivalent to the order in which wood is delivered to the company. Currently purchased assortments are not always taken into consideration when production plans are being executed. For example, it would not be an optimal solution to use

283 round wood, such asWC0 3 to make a rafter sized 180 x 80 mm. When we calculate the coupling, the optimal diameter is 250 mm. Thus, if we have wood of the third thickness class, we can obtain a considerable amount of side timber. In consequence, the material efficiency of the main product decreases. Thus, in view of the logistics of consecutive roof truss orders, the company acquires the wood whose quality and thickness classes enable the production of logs with required diameters after the wood has been manipulated. The quality and thickness classes should also guarantee that wood can be sawn into the largest possible amounts of the best quality timber. Percentage of wood mass WB0 0.37% 38.5% 5.5% 2.00% 4.53% WA0 1 WB0 55.9% 2 93.10% WC0 3 WD

WC0 WD 8.3% 41.0% 21.8% 28.5% 1 1 2 2 50.7% 49.7% 3 3

Figure 1. The percentage of wood mass. (Source: The author’s compilation)

We used the necessary pinewood material to analyse the percentage of acquired constructional elements in a typical hip or gableroof truss. The aim of the study was to calculate the percentage of individual elements in a roof truss ordered for production. We used twenty randomly selected orders for a complete roof truss (see the example in Table 1). We did not include the demand for timber for roof boarding or timber for laths and counterlaths. The roof construction is composed of elements such as: rafters, purlins, collars, wall plates, braces, posts, angle struts, ties, exchanges, ridge purlins, etc.

Table 1. An example of a roof truss order Thickness [cm] Width [cm] Length [cm] Pieces Volume [m3] 8 20 740 10 1,184 8 20 690 4 0,442 8 20 670 7 0,750 8 20 550 8 0,704 8 20 450 16 1,152 8 20 340 10 0,544 8 20 300 2 0,096 8 20 230 12 0,442 8 20 140 11 0,246 14 16 540 3 0,363 16 22 1060 3 1,119 16 22 540 1 0,190 14 20 600 2 0,336 14 20 330 2 0,185

284 14 20 300 2 0,168 7 14 480 4 0,188 14 14 270 10 0,529 14 14 400 13 1,019 14 14 450 2 0,176 14 14 500 1 0,098 14 14 300 2 0,118 Sum: 10,049 [m3] Source: The author’s compilation

When all orders were summed up, there was a total mass of 182.923 m3 of finished products. When we calculated the mass of each group of elements (rafters, collars, purlins, etc.), we obtained the following results – see Figure 2.

55.6%

15.4% 10.6% 8.4% 3.1% 1.9% 1.1% 0.8% 3.2%

rafters purlins wall collars posts ordered braces ridge et al. plates rafters

Figure 2. The percentage of roof truss components. (Source: The author’s compilation)

As can be seen in the chart, rafters are the main component of the roof truss, as they make about 56% of the total wood massvolume. Purlins and wall plates are also important assortments as they support rafters. Their share amounted to 15.4% and 11%, respectively. Collars are another group of elements combined with rafters. Their share amounted to 8% of the wood volume ordered. The share of ties amounted to about 2%. Posts and braces made 4% of the material volume ordered. The remaining 3.2% of the volume consisted of the elements whose presence depended on the roof design, i.e. purlins, indirect purlins, ridge beams, angle struts, basket rafters, ridge rafters, exchanges, eaves planks and ridge purlins.

ANALYSIS OF PRODUCTIVITY AND EFFICIENCY

Constructional wood is a material with high requirements concerning quality and strength. It comes from selected raw material, acquired in specific technological processes. It is meant to achieve adequate quality, especially high strength. These properties can be achieved by eliminationof wood defects in the sawing process. All these factors are related with variable indexes of material use. The quality of material is the main determinant of efficiency. Simultaneously, the quality is strictly related to the price of raw material. Figure 3 shows the average prices of WCO pinewood of the first thicknessclass, which were noted in the enterprise in 2014. The net price ranged from 209 zlotys per m3 (50.1 euros per m3, where the average exchange rate

285 in 2014 was 1 EUR = 4.17 PLN) in January 2014 to 226 zlotys per m3(54.2 euros per m3) in December 2014. 230 225 220 215 210 205 200 195

Price wood WCO1 w [zł/m3]

Figure 3. The price of WCO 1 material in 2014 (Source: The author’s compilation based on www.e- handeldrewnem.pl.)

As resulted from the questionnaire survey conducted in the sawmills under study, the average net purchase price of WCO class pinewood logs of the first thickness class was 210 zlotys per m3(50.3 euros per m3). As a result, individual price relations in the first quality and thickness class achieved the values shown in Table 2.

Table 2. The average prices of high-volume pinewood material

Quality class Thickness class 1 2 3 zł/ [netto] A - 343,14 420,21 B 231,0 284,3 324,66 C 210,0 245,49 279,72 D 160,65 174,72 189,63 Source: The author’s compilation based on analysis of the enterprises

Simultaneously, the price of finished pinewood assortments is equivalent to the price of high-volume pinewood. The prices reached the values shown in Tables 3-5, depending on the cross-section and type of assortment.

Table 3. Average prices of square-edge pine timber Square-edge timber Main material Measurement unit Net price [zl] Thickness/width [mm] < 200 800.00 > 200 850.00 Measurement perlength [m] 6-8 50.00 Side material (19, 22, 25) [mm] Length [m] > 2.2 550.00 < 2.2 350.00 Source: The author’s compilation based on analysis of the enterprises

286

Table 4. Average prices of non-square-edge pine timber Non-square-edge timber Quality class I II III IV Thickness [mm] unit Prices netto [zł] 19, 22, 25 500,00- 1000,00 32, 38, 45 700,00- 1250,00 50, 63, 75 800,00- 1500,00 Source: The author’s compilation based on analysis of the enterprises

Table 5. Average prices of floorboard Finished products Flooring board ( 28) [mm] Length[m] unit Prices netto [zł] < 2,5 40,00 2,5- 3,5 45,00 3,5- 4,5 50,00 Source: The author’s compilation based on analysis of the enterprises

Three quality classes of sawmill wood were used in the research. The wood was divided into logs, constructional timber and 25-mm thick non-square-edge side timber. Next, the assortments were sorted and classified in order to find zones without the defects which would limit their use asconstructional timber. Simultaneously, an additional aspect of qualitative analysis of wood materials was introduced, i.e. the areas which were in theory free from defects were separated in the following length ranges: A – up to 1000 mm, B – up to 750 mm, C – up to 500 mm, where element A was the basic unit. The analysis revealed that: • visual assessment of timber showed the relation between the quality of pine sawmill material and the efficiency of elements, • the efficiency of element A was the highest in the first quality class of sawmill material – up to about 55%, • the efficiency of element A in the second class was 35.5% and in the third class it was 33.2%, • the enterprises purchased the third quality class sawmill material more readily, because they achieved high economic effects with lower financial outlay. Appropriate selection of final products directly influences the increase in rational wood processing. This fact is confirmed by literature data (Buchholz 1968,Krzosek 2009). The observation of the pinewood log sawing process in the selected wood manufacturing plant revealed variability of material efficiency and production efficiency indexes, which points to the fact that the issue needs to be constantly analysed. When we take the acquired main timber, which consists of individual sorted elements of the roof construction, and their average efficiency, having deducted the mass for accompanying materials made in the production process, we can calculate the average production efficiency index for these elements. Thickness/width >200 [mm] • rafters – average assortment efficiency (Wst) 60% Ep= 2.17[zlotys/zlotys] • purlins – average assortment efficiency (Wst) 65% Ep= 2.37[zlotys/zlotys] • wall plates – average assortment efficiency (Wst) 75% Ep= 2.71 [zlotys/zlotys] • collars, posts, ties – average assortment efficiency (Wst) 55%Ep= 1.99 [zlotys/zlotys] Thickness/width <200 [mm] • rafters – average assortment efficiency (Wst) 60% Ep= 2.04 [zlotys/zlotys] • purlins – average assortment efficiency (Wst) 65% Ep= 2.21 [zlotys/zlotys]

287 • wall plates – average assortment efficiency (Wst) 75% Ep= 2.55 [zlotys/zlotys] • collars, posts, ties – average assortment efficiency (Wst) 55% Ep= 1.87 [zlotys/zlotys] Simultaneously, allowing for the cross-section of the element, we can take the length variable into consideration, as it will cause variation in the price of material. The longer the dimension and the more diversified the cross-section is, the higher class of the log thickness is required. This results in a higher price. We can calculate efficiency for this diversification. Thickness/width >200 [mm],6 < L > 8 • rafters – Wst 55% Ep= 1.99 [zlotys/zlotys] • purlins – Wst60% Ep= 2.16 [zlotys/zlotys] • wall plates – Wst70% Ep= 2.50 [zlotys/zlotys] • collars, posts, ties – Wst 50% Ep= 1.83 [zlotys/zlotys] Thickness/width <200 [mm],6 < L > 8 • rafters – Wst about 55% Ep= 1.89 [zlotys/zlotys] • purlins – Wst about 60% Ep= 2.04 [zlotys/zlotys] • wall plates – Wst about 70% Ep= 2.26 [zlotys/zlotys] • collars, posts, ties – Wst about 50% Ep= 1.73 [zlotys/zlotys] The results of the analysis show that the production efficiency tends to decrease depending on thickness. The highest efficiency can be observed in wall plates andpurlins, because they are characterised by high assortment efficiency. The percentage of material use increases due to the application of maximum couplings, where the cross-section is close to a square. However, when we consider the element length, which isa variable factor due to varying prices of the assortment and varying prices of the material, we can observe a considerable decrease in theefficiency, when we compare it with the results of sawing the assortments whose length does not exceed 6 metres.

SUMMARY AND CONCLUSIONS

The research resulted in the following observations and conclusions: 1. Class WC0 was the predominant class of high-volume wood processed into constructional assortments. The minimal share of class WBO purchased indicates the material cost reduction policy. 2. The analysis of individual raw material quality classes showed that thickness class 2 was predominant in each quality class. 3. Rafters, purlins and wall plates were the predominant roof truss components ordered. 4. The quality of raw material is the main determinant of its usefulness for timber production, whereas the price is the main determinant of its efficiency. 5. The ratio between the product price and the material price is decisiveto production efficiency. The influence of raw material quality on its value can be identified by the rate of increase in the constructional assortments efficiency. 6. The highest efficiency rates are achieved by processing sawmill material of quality class 1. Simultaneously, a higher share of quality class 3 material and adequate selection of final products may reduce costs and result in higher efficiency than in the processing of high quality wood, which has much higher prices on the market. 7. The highest production efficiency was found in general processing of pinewood into purlins and wall plates. Depending on the product price and the price, dimension and length of raw material, these components achieved the highest efficiency while retaining the same quality criteria.

288 REFERENCES 1. Buchholz J. (1968): Zagadnienie klasyfikacji sosnowego drewna tartacznego na tle rachunku ekonomicznego w przemyśle tartacznym. Folia Forestalia Polnica Seria B, 8: 95-127. 2. Dzbeński W., Kozakiewicz P., Krzosek S. (2005): Wytrzymałościowe sortowanie tarcicy budowlano- konstrukcyjnej. Wydawnictwo SGGW. Warszawa 2005. 3. Hruzik J.G., Gotych W., Wieruszewski M. (2005): Efektywność produkcji przykładowych wyrobów tartacznych na rynek krajowy i europejski, w: Przemysł Drzewny, Maj 2005, Wydawnictwo Świat. Warszawa, s. 18-21. 4. Korczewski O., Krzysik F., Szmit J. (1970): Tartacznictwo. Państwowe Wydawnictwo Naukowe. Warszawa 1970. 5. Krzosek S. 2009: Wytrzymałościowe sortowanie polskiej sosnowej tarcicy konstrukcyjnej różnymi metodami. Wydawnictwo SGGW. Warszawa 2009. 6. Lis W., Mydlarz K – Der Einfluss der Globalisierung auf Hersteller von Holzhäusern in Skelettkonstruktion. „Intercathedra” No 24, Annual Scientific Bulletin of Plant - Economic Departments of the European Wood Technology University Studies. ISSN 1640-3622. Poznań 2008, s. 66 – 69. 7. Mańkowski P., Krzosek S., Mazurek A. (2011): Compressionstregth of pine Wood ( Pinus Sylvestris L.) fron selected forest regions in Poland. Annals of Warsaw University of Life Science 2011, No 75: 81-84. 8. Mydlarz K. (2008): Analiza czynników technologicznych I ekonomicznych warunkujących rozwój drewnianego budownictwa szkieletowego w Polsce. Poznań 2008, s.35-36. 9. Mydlarz K., Wieruszewski M. (2012): Solid and engineered wood and its significance for innovative solutions in timber building projects. Intercathedra 2012, No 28-3: 58- 61. 10. PN-EN 14081-1+A1:2011 Konstrukcje drewniane- Drewno konstrukcyjne o przekroju prostokątnym sortowane wytrzymałościowo- Część 1: Wymagania ogólne. 11. PN-EN 14081-2:2010 Konstrukcje drewniane- Drewno konstrukcyjne o przekroju prostokątnym sortowane wytrzymałościowo -- Część 2: Sortowanie maszynowe; wymagania dodatkowe dotyczące wstępnych badań typu 12. PN-EN 14081-2+A1:2013-05 Konstrukcje drewniane - Drewno konstrukcyjne o przekroju prostokątnym sortowane wytrzymałościowo - Część 2: Sortowanie maszynowe; wymagania dodatkowe dotyczące wstępnych badań typu”. 13. PN-EN 14081-3:2012Konstrukcje drewniane- Drewno konstrukcyjne o przekroju prostokątnym sortowane wytrzymałościowo- Część 3: Sortowanie maszynowe: wymagania dodatkowe dotyczące zakładowej kontroli produkcji. 14. PN-EN 14081-4:2009Konstrukcje drewniane- Drewno konstrukcyjne o przekroju prostokątnym sortowane wytrzymałościowo- Część 4: Sortowanie maszynowe - Nastawy urządzeń sortujących do kontroli maszynowej. 15. PN-EN 1995-1-1: 2010 Eurokod 5: Projektowanie konstrukcji drewnianych - Część 1-1: Zasady ogólne i zasady dla budynków. 16. PN-EN 1995-1-2:2008 Eurokod 5: Projektowanie konstrukcji drewnianych - Część 1- 2:Postanowienia ogólne - Projektowanie konstrukcji z uwagi na warunki pożarowe. 17. PN-EN 1995-2:2007 Eurokod 5: Projektowanie konstrukcji drewnianych - Część 2: Mosty. 18. PN-EN 350-2:2000 „Trwałość drewna i materiałów drewnopochodnych -- Naturalna trwałość drewna litego -- Wytyczne dotyczące naturalnej trwałości i podatności na nasycanie wybranych gatunków drewna mających znaczenie w Europie”.

289 19. PN-EN 384 Drewno konstrukcyjne. Oznaczenia wartości charakterystycznych właściwości mechanicznych i gęstości. 20. PN-EN94021:2013 Tarcica iglasta konstrukcyjna sortowana metodami wytrzymałościowymi, które wykażą, czy dany element spełnia określone wymagania 21. www.e-handeldrewnem.pl (11.11.2015)

Streszczenie: Wpływ struktury ilościowo- wymiarowej elementów więźb dachowych na wydajność materiałową przetarcia oraz efektywność ich produkcji. W pracy ustalono przykładową strukturę jakościowo-ilościową surowca drzewnego, wyznaczono wydajność materiałową przetarcia dla poszczególnych elementów więźby dachowej. Przeprowadzono analizę procentową składowych elementów konstrukcji typowej więźby dachowej i wyznaczono efektywność produkcji. Wskazano czynniki mające wpływ na efektywność przerobu surowca. Ustalono dominującą klasę przerabianego dla potrzeb pozyskania sortymentów konstrukcyjnych drewna wielkowymiarowego.

Corresponding author:

Marek Wieruszewski Ul. Wojska Polskiego 28 60-637Poznań, Polska email: [email protected] phone: 501756470

Katarzyna Mydlarz Ul. Wojska Polskiego 28 60-637Poznań, Polska email: [email protected] phone: .618487427

290 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 291-296 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Thermography as a method of structural analysis of historic wooden buildings PIOTR WITOMSKI1, ADAM KRAJEWSKI1, 1 Department of Wood Science and Wood Protection, Warsaw University of Life Sciences - SGGW Abstract: Thermography as a method of structural analysis of historic wooden buildings. The article presents the results of thermographic tests of the Temple of Diana in the Park-and-palace complex of the Royal Łazienki Museum. The research was conducted in 2010… using a thermal imaging camera made by FLIRT, with the resolution of 0,001ºC. Satisfactory results have been achieved for the difference between temperatures inside and outside the building of 15ºC. The temperature inside was about +8ºC, and the temperature outside was -7ºC.

Keywords: wooden construction, thermography, conservatory works

INTRODUCTION The necessity of determining the type of construction, as well as the nature of destruction present in its structure, is a very common issue in conservatory works. If the supportive structure of a building is covered with finishing materials, such as plaster, wood panelling, or formwork, intervention into top layers must be made. Performing outcrops in order to examine the internal layers is usually connected with a certain degree of disassembly or even destruction of the finishing layers, which is unacceptable in the case of precious paintings or moulding. For that reason, research is being performed on non-destructive methods, allowing to visualise the invisible internal structures. The research includes methods applied also in Poland, such as radiography (Krajewski and Witomski, 2004, 2005a, Krajewski et al. 2005a), computed tomography (Krajewski and Witomski 2005b, Krajewski et al. 2005a, 2005b, Witomski et al. 2015), video endoscopy (Krajewski and Witomski 2005c, 2005d, Witomski 2006, Witomski and Krajewski 2007). One of the methods is thermography. It is based on the differences of temperature in different parts of the object, resulting from different thermal conductivity of materials. In static thermography method, heat flux transferred from heated interior of the building is measured, while in dynamic thermography differences are registered in absorption of heat flux by the surface of the building, heated from the inside by particular heat impulses. This allows to reveal and visualise thermal bridges occurring in parts of different thermal conductivity. The thermal bridges may occur on the borders of different materials or in the case of varying thickness inside a partition. By visualising them, differences can be revealed in materials hid below the finishing layers, such as plaster or formwork, as well as damage done to the wood by fungi and insects. Additionally, in the case of wooden buildings, moist parts are revealed, having a better thermal conductivity. The presence of moist wood can suggest fungal attack in the wood. Between 2010 and 2012 conservatory works were performed in the Temple of Diana in the Park-and-palace complex of the Royal Łazienki Museum. Due to the lack of reports in available source materials on the type of construction of the temple in question, an attempt was made to determine roughly the type of constructional solution used in the building by means of non-destructive methods. Neither the preserved descriptions of the building, nor the fragmentary drawing documentation did not reveal the true construction of the building. The only verified fact was that each of the columns is made from a solid piece of wood from a single trunk. Thus, during conservatory works, it was necessary to analyse the construction of the temple. Thermographic analysis was performed in order to avoid extensive outcrops in the formwork.

291

MATERIAL AND METHODS As it was mentioned above, the object examined thermographically regarding its construction and condition, was the Temple of Diana (Fig.1.) in the Park-and-palace complex of the Royal Łazienki Museum. The colonnade surrounding the building consists of 16 columns of Ionic order (with a 4-column prostyle).

Fig.1. Temple of Diana

On a Roman-style plinth, a wooden stylobate is placed, providing a basis for the colonnade (Fig.2.,3.). The cella of the temple is covered with a horizontal boarding, imitating banded rustication, finished with mat white oil paint. The gable roof is leaned against a wooden rafter. Front facade (on the south side) contains double panel doors. In the back (on the north side) similar, yet blind, doors are placed. Inside, the walls are finished with plaster on cane. Faux vault is placed on boarding.

Fig. 2. The drawing of the temple facades

292

Fig. 3. The longitudinal section of the temple

Thermographic method was used for the examination of the object. For this purpose, the interior of the temple was heated for 12 hours. Measurements were conducted on a cloudy day after sunset. The difference between the temperature of the interior and the temperature outside was 15ºC. The temperature of the interior was +8ºC and the temperature outside was - 7ºC. The measurements were performed using a thermal imaging camera made by FLIRT, with the resolution of 0,001ºC.

RESULTS AND DISCUSION The building, seemingly built from stone, is in fact a wooden construction. It is a pavilion in the shape of peripteros, surrounded by a single colonnade (Fig. 1). The columns are also made from solid wood. The colonnade is based on a wooden stylobate (Fig. 3). By observing the differences in thermal conductivity of compartments (i.e. walls of the object), thermal bridges were found, revealing differences in the internal structure of the compartments (Fig.4.,5.,6.). On this basis, under the boarding of the elevation, internal framing of the building was discovered (Fig.4.,5.,6.). On the photos, oblique struts can be seen between the corners of the cella and the vault, leaning against door and window lintels. The framing was confirmed by performing a local outcrop, which revealed entablature of the frame of 200-mm cross-section under the plaster visible on the cane and boarding. On the photos, a wooden barrel of the vault could also be seen.

293

Fig. 4. Internal framing of the building revealed under the boarding of the elevation

. Fig. 5. Internal framing of the building revealed under the boarding of the elevation

Fig. 6. Internal framing of the building revealed under the boarding of the elevation

294

CONCLUSIONS The thermographic method using a thermal imaging camera made by FLIRT gave fully satisfactory results at a 15-degree difference in temperatures between the interior and the outside of the building. The most important result was the indication of a wooden construction of the walls of the building, finished on both sides with formwork, imitating plaster-covered walls.

LITERATURE 1. Biegański T., Krajewski A., Perkowski J., Rybka K., Witomski P. (2003). Tomografia komputerowa jako metoda wykrywania i obserwowania owadów w drewnie. Przemysł drzewny. nr 12, 17-18. 2. Krajewski A., Narojek T. Witomski P. (2005) The detection of old House borer larvae In wood by means of x-ray computed tomography. Annals of Warsaw Agricultural University, 2005, nr 55, 363-368. 3. Witomski P., Krajewski A., Narojek T. 2010: Measurements of wood density using X- ray computer tomography. Annals of Warsaw Agricultural University, nr 72, 485- 489. 4. Krajewski A., Witomski P. (2004) : From the research on the use of X-rays for detection of old house longhorn beetle in wood, Annals of Warsaw Agricultural University, nr 55, 295 – 300. 5. Krajewski A., Witomski P. (2005a) Wykrywalność różnych gatunków ksylofagicznych owadów w drewnie na zdjęciach rentgenowskich. Postęp i nowoczesność w konserwacji zabytków. Problemy – perspektywy. Lublin, 82-91. 6. Krajewski A., Witomski P. (2005b) Detekcja biodegradacji drewna. Postęp i nowoczesność w konserwacji zabytków. Problemy – perspektywy. Lublin, 92-99. 7. Krajewski A., Witomski P. (2005c) Videoendoskopia jako metoda oceny stanu drewnianych konstrukcji w zabytkach. Ochrona Zabytków, nr.4, 105-108. 8. Witomski P., Krajewski A., Bonecka J., Serafinowicz M. (2015) Modern methods of diagnosis of wood condition of ancient sculptures, Annals of Warsaw University of Life Science – SGGW. Forestry and Wood Technology. No 91, 206-211.

295

Streszczenie: Termografia jako metoda analizy konstrukcyjnej zabytkowych obiektów drewnianych. Przedstawiono wyniki badań termograficznych Świątyni Diany w Zespole Pałacowo-Ogrodowym Muzeum Łazienki Królewskie. Prace badawcze przeprowadzono kamerą termowizyjną firmy FLIR o rozdzielczości do 0,001 oC. Uzyskano satysfakcjonujące wyniki przy różnicy temperatur między wnętrzem a zewnętrzem budynku ok. 15oC, ujawniając ukrytą pod szalunkiem rzeczywista konstrukcję budowli.

Author‘s addresses

Piotr Witomski [email protected] Department of Wood Science and Wood Preservation Faculty of Wood Technology Warsaw University of Life Sciences - SGGW Nowoursynowska 166 02-787 Warsaw, Poland

Adam Krajewski [email protected] Department of Wood Science and Wood Preservation Faculty of Wood Technology Warsaw University of Life Sciences - SGGW Nowoursynowska 166 02-787 Warsaw, Poland

296 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 297-300 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

An attempt to determine the amount of mycelium in wood decayed by white-rot fungi Trametes versicolor and brown-rot fungi Coniophora puteana based on ergosterol content

PIOTR WITOMSKI, BOGUSŁAW ANDRES, ADAM KRAJEWSKI, MICHAŁ ANISZEWSKI, EWA LISIECKA, ANNA OLEKSIEWICZ Warsaw University of Life Science, Faculty of Wood Technology, Department of Wood Science and Wood Protection, Warsaw, Poland

Abstract: An attempt to determine the amount of mycelium in wood decayed by white-rot fungi Trametes versicolor and brown-rot fungi Coniophora puteana based on ergosterol content. The amount of mycelium in wood was determined basing on the amount of ergosterol, a characteristic sterol contained in mycelium, present in the sample. The method consisted of evaluating the amount of ergosterol by means of spectrophotometric measurements conducted at a particular wavelength, at which ergosterol gives a characteristic, distinct spectrum. The measurements of ergosterol amount in wood at different stages of decay showed no relationship between the content of this sterol and the stage of wood decay.

Keywords: ergosterol, fungal biomass, white-rot fungi, brown-rot fungi, wood

INTRODUCTION Ergosterol is a steroid alcohol contained in cell membranes of almost all species of fungi. Due to its specificity to fungi, the compound is widely used as a bioindicator of fungal attack on different kinds of food products of plant origin. The indicator can also be applied to testing other products, like building materials, including wood. Unfortunately, such examinations are mostly concerned with moulds (Hippelein, Rügamer 2004, Bjurman 1994), while only few papers discuss fungi causing wood decay (Niemenmaa et al. 2008). Using ergosterol to monitoring the level of fungal attack on different materials has been widely analysed. Examinations have been undertaken to correlate the content of ergosterol with the level of fungal attack on substrate, as well as to evolve norms determining the permissible level of ergosterol content in materials. An attempt of evaluating the permissible ergosterol content in building materials has been ventured by Gutarowska and Żakowska (2000). They determined the ergosterol content of 0.1 mg/m2 of the surface as not indicating an active fungal growth inside the material. However, the content of ergosterol in fungi-attacked materials does not necessarily have to correlate with the biomass of mycelium, which depends on many factors like the species of fungi, conditions and time of raising, nutritional substances in the substrate, temperature, and pH (Dawson-Andoh 2002).

MATERIAL AND METHODS The samples used in the examination were made from Scots pine wood (Pinus sylvestris L). They were exposed to controlled decomposition in accordance with a modified procedure from the PN-EN-113 standard. The biological material consisted of two testing fungal species, namely Coniophora puteana (Schum.: Fr.) P. Karst., causing brown rot, and Trametes versicolor (L.: Fr.) Pilát, causing white rot. Fungal decay was performed for a period of up to 4 months in case of Coniophora puteana and for a period of up to 12 months in the case of Trametes versicolor. Every week, 4 samples were taken out of culture vessels with Coniophora puteana cultures. Also, 4 samples were taken out of culture vessels with Trametes versicolor cultures every week in the first month, every two weeks in the second

297 month, and every four week throughout the rest of the experiment. Thanks to that, samples were obtained of a gradually increasing degree of decomposition. After each period of the decay process, samples were taken out of culture vessels and dried in the temperature of 105oC to a solid state (0% moisture content) and each of the samples was then weighed with accuracy of 0.01 g in order to establish its final mass (mk). In the next stage, the samples prepared as described above were subjected to tests. The examinations were conducted using Seitz method (Seitz et al. 1979), modified in the Institute of Fermentation Technology and Microbiology, University of Technology Lodz (Gutarowska, Żakowska 2000). Wood samples of approximately 5g were crushed to shavings, dipped into 50 cm3 of methanol and put inside a flask with SJ of 500 cm3 capacity. The mixtures were shaken on a vortex mixer for 30 minutes at 150 rotations per minute. Methanol was then poured down into cuvettes, and the remainders of the shavings were again dipped into 50 cm3 of methanol and shaken for 10 minutes. Methanol solutions were then mixed and shaken for 10 minutes at 2700 rotations per minute. For further examination, supernatant was used. It was put into a flask with SJ of 300 cm3 capacity. After adding 5ml of 1M KOH solution, the mixture was placed in a reflux condenser for 30 minutes. After cooling the sample to the temperature of approximately 4oC, it was extracted with 50 cm3 of hexane two times for 2 minutes. The upper hexane fraction, containing sterols, was vaporised to dryness in a rotary evaporator. The dry remainder was dissolved in 30 cm3 of methanol and subjected to spectrophotometric analysis. The measurement of absorbance was conducted using a UV2 spectrophotometer made by Unicam, at a wavelength λ= 282,6 nm.

RESULTS AND DISCUSION The measurement of absorbance of ergosterol solutions extracted from fungi-decayed wood is shown in Fig. 1 and Fig. 2. No measurable differences between extracts from fungi-attacked wood and non- attacked wood were noticed. In the case of white-rot fungus Trametes versicolor the measured values were even bigger than those of a non-attacked reference (control) samples.

1,2

0,8

0,6 absorbancja

0,4

0,2

0 0 1,11 4,8 9,1 17,6 20,8 25,1 29,6 34,98 40,7 44,3 51,2 ubytek masy (%)

Fig. 1. Absorbance of methanol solutions of ergosterol extracted from wood decayed by white-rot fungus Trametes versicolor (at wavelength λ= 282,6 nm).

298 1,8

1,6

1,4

1,2

0,8 absorbancja

0,6

0,4

0,2

0 0 2,4 4,89 9,54 14,9 20,5 25 28,8 ubytek masy (%)

Fig. 2. Absorbance of methanol solutions of ergosterol extracted from wood decayed by brown-rot fungus Coniophora puteana (at wavelength λ= 282,6 nm).

Examining samples of wood attacked by brown-rot fungus Coniophora puteana, in spite of a two times bigger value of absorbance of extracts from fungi-attacked wood, as compared to non-attacked wood, no regularity was observed between the content of mycelium and the degree of wood decay. Attempts to determine a correlation between the degree of wood decay and the content of mycelium based on determining ergosterol content have not brought expected results. As stated by Żakowska et al. (1999), the method of quantitative marking of mycelium based on ergosterol observation gives very reliable results in the case of moulds growing on plasterwork. However, in the case of ergosterol extracted from wood tissue, the applied procedure has not given reliable results. Ergosterol is a relatively durable compound, yet the research of Mille-Lindblom et al. (2004) confirmed a very quick degradation of ergosterol under the influence of sunlight. It is thus conceivable that ergosterol contained in the wood samples was degraded as a result of the actions undertaken during the preparation of fungi-attacked wood samples, such as the process of drying in the temperature of 105oC or irradiation with light, including UV, of the crushed shavings during crushing before extraction.

CONCLUSION • Measured values of ergosterol content in wood of various degree of decay have not shown relationship between the content of the sterol and the degree of decay. • In the wood decayed by white-rot fungus Trametes versicolor the content of ergosterol was higher than in wood not attacked by fungi. • In the wood decayed by brown-rot fungus Coniophora puteana the content of ergosterol was twice as high as in wood not attacked by fungi. However, no relationship was observed between the content of mycelium and the degree of wood decay.

299 REFERENCES 1. Bjurman J 1994: Ergosterol as an indicator of mould growth on wood in relation to culture age, humidity stress and nutrient level. Int. Biodeterioration and Biodegradation. Vol.33 (1994) 355-368. 2. Dawson-Andoh B. E. 2002: Ergosterol content as a measure of biomass of potential biological control fungi in liquid cultures. Holz als Roh- und Werkstoff 60, 115-117. 3. Gutarowska B., Żakowska Z. 2000: Oznaczanie zawartości ergosterolu w materiałach budowlanych – metoda oceny stopnia zanieczyszczenia grzybami strzępkowymi Rozkład i korozja mikrobiologiczna materiałów technicznych. Wyd. Sigma-NOT, Warszawa. 4. Hippelein M., Rügamer M. 2004: Ergosterol as an indicator of mould growth on building materials. Int. J. Hyg. Environ. Health 207 (2004); 379-385. 5. Mille-Lindblom C., Wachenfeldt E., Tranvic L. J. 2004: Ergosterol as a measure of living fungal biomass: persistence in environmental samples after fungal death. Journal of Microbiological Methods 59 (2004) 253–262. 6. Niemenmaa O., Galkin S., Hatakka A. 2008: Ergosterol contents of some wood-rotting basidiomycete fungi grown in liquid and solid culture conditions. International Biodeterioration & Biodegradation 62 (2008) 125–134. 7. Seitz L. M., Sauer D. B., Mohr H. E., Hubbard J. D. 1979: Ergosterol as a measure of fungal growth. Phytopathology 69, 1202-1203. 8. Żakowska Z., Bogusławska – Kozłowska J. Gutarowska B. 1999: Laboratoryjne metody wykrywania grzybów pleśniowych w materiałach budowlanych. [in:] V Sympozjum PSMB „Ochrona obiektów budowlanych przed korozją biologiczną i ogniem” Mąchocice – Ameliówka. 119-125.

Streszczenie: Próby oznaczania ilości grzybni w drewnie rozłożonym przez grzyby rozkładu białego Trametes versicolor i brunatnego Coniphora puteana na podstawie zawartości ergosterolu oraz zawartości ergosterolu od stanu rozkładu drewna. Oznaczanie ilości grzybni w drewnie oparto na określeniu zawartości w próbce charakterystycznego sterolu zawartego w grzybni – ergosterolu. Metoda polegała na oznaczaniu ilości ergosterolu metodą spektrofotometryczną przy długości fali, w której ergosterol daje charakterystyczne, wyróżniające go widmo. Oznaczenia ergosterolu w drewnie w różnych stadiach rozkładu nie wykazały zależności zawartości tego sterolu od stadium rozkładu drewna.

Corresponding authors

Piotr Witomski Warsaw University of Life Science, Faculty of Wood Technology Department of Wood Science and Wood Protection Warsaw Poland Nowoursynowska 159 02-787 Warszawa e_mail: [email protected]

300 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 301-304 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Changes of cellulose crystallinity determined microscopically in polarised light PIOTR WITOMSKI, ADAM KRAJEWSKI, BOGUSŁAW ANDRES, MICHAŁ ANISZEWSKI, EWA LISIECKA, ANNA OLEKSIEWICZ Warsaw University of Life Science, Faculty of Wood Technology, Department of Wood Science and Wood Protection, Warsaw Poland

Abstract: Changes of cellulose crystallinity determined microscopically in polarised light In the course of estimating the changes of cellulose crystallinity in wood decayed by two fungi species Trametes versicolor and Coniophora puteana, despite visible changes in appearance (Fig. 1, Fig. 2), quantitative analysis of brightness of digitally recorded photographs did not show any substantial differences in dimming of the image, as related to a progressive wood decay.

Keywords: cellulose crystallinity, polarised light, wood decay

INTRODUCTION Crystallinity of cellulose in wood is defined as an arrangement of cellulose chains in parallel directions and their connection by hydrogen bonds in transverse direction. As a result, areas of wood with crystal cellulose adopt a three-dimensional, ordered structure. It is characterised by high density and high elastic moduli, which makes cellulose very resistant, both physically and chemically (Kokociński, 2002). The phenomenon of cellulose crystallinity, sometimes called paracrystallinity, was discovered in 1858 by a Swiss botanist Nägeli. His theory, however, was widely accepted only after its confirmation by X-ray and electron microscope examinations in the beginning of the 20th century. The development of X-ray examinations allowed to observe the content of crystallites, called micelles, in cellulose (Kocoń, 1964), and to estimate the ratio of crystal mass in total mass of cellulose, i.e. the crystallinity level of wood, ranging between 69% and 71% (Kokociński, 2002). Further research determined the crystal system of cellulose (Prosiński, 1984). Crystallinity of cellulose can be examined with various methods, including gamma rays, X-ray diffraction and infra-red (IR) spectroscopy. Changes of cellulose crystallinity as a result of various wood-degrading processes was also determined by means of Fourier Transform Infrared (FTIR) Spectroscopy (Kasprzyk and Wichłacz, 2004; Yildiz and Gümüskaya, 2005). On the other hand, petrographic microscope technique is often applied to observe areas of both preserved and degraded crystal structure of archaeological wood, i.e. to observe destroyed and well-preserved parts (Rowell and Barbour, 1990). In this context, an attempt was made to determine a relationship between cellulose crystallinity, measured using petrographic microscope method, and the degree of wood decay.

METHODS The samples used in the examination were made from Scots pine wood (Pinus sylvestris L). They were exposed to controlled decomposition in accordance with a modified procedure from the PN-EN-113 standard. The biological material consisted of two testing fungal species, namely Coniophora puteana (Schum.: Fr.) P. Karst., causing brown rot, and Trametes versicolor (L.: Fr.) Pilát, causing white rot. Fungal decay was performed for a period of up to 4 months in case of Coniophora puteana and for a period of up to 12 months in the case of Trametes versicolor. Every week, 4 samples were taken out of culture vessels with Coniophora puteana cultures. Also, 4 samples were taken out of culture vessels with

301 Trametes versicolor cultures every week in the first month, every two weeks in the second month, and every four week throughout the rest of the experiment. Thanks to that, samples were obtained of a gradually increasing degree of decomposition. After each period of the decay process, samples were taken out of culture vessels and dried in the temperature of 105oC to a solid state (0% moisture content) and each of the samples was then weighed with accuracy of 0.01 g in order to establish its final mass (mk). In the next stage, the samples prepared as described above were subjected to tests.

Fig. 1. A photograph of healthy Scots pine wood in polarised light – visible bright image.

Mini-samples sized 20x5x5 mm were made from wood of various degree of decay. The samples were soaked for 72 hours in wood-softening solution containing glycerol, ethanol and water (in volume ratios 1:1:1). After softening, the wood was sliced radially with a microtome into flakes sized 5x5mm and 60μm thin. The flakes were used to create microscopic preparations, which were examined using a petrographic microscope Olympus Provis AX 70 at 40x and 200x magnitudes. The images were recorded using a digital camera at constant exposure parameters. Next, using a graphics computer program Idrisi 32, brightness of each photograph was measured. Decreasing of brightness in polarised light, caused by decreasing of crystallinity level of cellulose, was compared to the degree of wood decay, expressed by mass loss.

RESULTS AND DISCUSSION The results of decreasing of cellulose crystallinity, measured by dimming of the image, is shown in Fig. 3 and Fig. 4. In the course of estimating the changes of cellulose crystallinity in wood decayed by two fungi species T. versicolor and C. puteana, despite visible changes in appearance (Fig. 1, Fig. 2), quantitative analysis of brightness of digitally recorded photographs did not show any substantial differences in dimming of the image, as related to a progressive wood decay. It is possible that the applied technique gives only general image and allows to distinguish degraded areas from well-preserved areas of wood, but does not allow to estimate the degree of decay quantitatively. Perhaps some other methodological assumptions, e.g. using different

302 sections of wood in the measurements or applying some more precise measuring apparatus with appropriate correction filters, would allow to obtain more reliable results.

Fig. 2. A photograph of decayed Scots pine wood in polarised light – a distinct dimming of the image can be observed.

300

250

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150

jasność obrazu jasność 100

0 0 10 20 30 40 50 60 ubytek masy (%)

Fig. 3. The relationship between brightness of image and loss of mass of wood caused by growth of T. versicolor.

303 300

250

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150 jasnośćobrazu 100

0 0 5 10 15 20 25 30 35 ubytek masy (%)

Fig. 4. The relationship between brightness of image and loss of mass of wood caused by growth of C. puteana.

REFERENCES 1. Kasprzyk H., Wichlacz K. 2004: „Some aspects of estimation of the crystallinity of gamma radiation wood cellulose by FTIR spectroscopy and X-ray diffraction techniques”, Acta Scientiarum Polonorum, Silvarum Colendarum Ratio et Industria Lignaria, vol. 3(1): 73-84. 2. Kocoń J. 1964: „Badanie uporządkowania micel celulozy w drewnie świerka, sosny, modrzewia i buka promieniami rentgenowskimi w zależności od szerokości rocznego przyrostu” Instytut Drzewnictwa (typescript), Warszawa. 3. Kokociński W. 2002: Anatomia drewna, Wydawnictwo-Drukarnia Prodruk, Poznań. 4. Nägeli, C. 1858: Die Stärkekörner: Morphologische, physiologische, chemisch- physicalische und systematisch-botanische Monographie. Pflanzenphysiologische Untersuchungen. 2. Heft. Zürich: bei Fredrich Schultness. 5. Prosiński S. 1984: Chemia drewna, PWN, Warszawa. 6. Rowell R. M., Barbour R.J., 1990: Archaeological Wood Properties, Chemistry, and Preservation. American Chemical Society, Washington. 7. Yildiz Sibel, Gümüskaya Etat 2005: The effects of thermal modification on crystalline of cellulose in soft and hardwood, Building and Environment, vol. 42 (1): 62-67.

Streszczenie: Zmiany krystaliczności celulozy wyznaczane metodą mikroskopową w świetle spolaryzowanym. Do określania zmian krystaliczności celulozy w drewnie rozłożonym przez grzyby T. versicolor i C. puteana zastosowano mikroskopię spolaryzowaną. Porównując ze sobą wykonane zdjęcia widać różnice w jasności obrazu, jednak analiza ilościowa jasności zapisanych cyfrowo zdjęć nie wykazała istotnych różnic zaciemnienia obrazu postępującego wraz z rozkładem drewna.

Corresponding authors

Piotr Witomski Warsaw University of Life Science, Faculty of Wood Technology Department of Wood Science and Wood Protection Warsaw Poland Nowoursynowska 159 02-787 Warszawa e_mail: [email protected]

304 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 305-309 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Single item deacidification of paper with dispersion of magnesium hydroxide nanoparticles in alcohol: the problem of process efficiency

ADAM WÓJCIAK Institute of Chemical Wood Technology, Poznań University of Life Sciences, ul. Wojska Polskiego 38/42, 60- 637 Poznań, Poland

Abstract: The aim of the study was to assess the efficiency of paper deacidification using magnesium hydroxide particles of nanometric dimensions. The techniques used included pH measurements of aqueous extracts, determination of the degree of polymerization (DP) of cellulose both for artificially acidified and iron gall ink- covered papers, and scanning electron microscopy (SEM) with SE and EDX detectors. From the analyses it follows that nanoparticles make it possible to obtain alkaline pH values of aqueous extracts of paper and reduce cellulose degradation, which attests to the effectiveness of the procedure. Following deacidification, deposits of magnesium compounds are mainly found on the surface of samples, however some nanoparticles are also seen to penetrate into voids within the paper structure.

Keywords: paper deacidification, magnesium hydroxide, nanoparticles

INTRODUCTION The problem of acidic degradation of historical and archival papers, which has its source in the technology of acidic sizing and SO2 absorption from the air, represents one of the most important challenges faced by paper conservators nowadays (Sobucki 1999, Strlič and Kolar 2002). In order to halt the process of destruction of cultural heritage, a range of paper deacidification methods have been developed (Baty 2010). Based on the type of solvent used, deacidification can be aqueous or based on non-aqueous solvents. The selection of solvent is determined not only by the efficiency of incorporating an alkalizing agent into paper but also its impact on the inscription, e.g. iron gall ink, print, pencil, etc. The main disadvantage of aqueous deacidification is paper deformation in the form of surface undulations. Organic solvents, which do not induce the swelling of fibres, ensure a greater dimensional stability of paper. When organic solvents are used, deacidifying agent particles occur in the form of a dispersion. Paper deacidification by means of a dispersion, i.e. suspension of solid particles in a solvent solution, gives rise to the question of how efficiently the deacidifying agent penetrates into the internal structure of paper, and hence to what extent the acids contained in the paper are neutralized. The penetrability of deacidifying agents into paper pores and fibres is limited by particle size. Consequently, attention was drawn to the possibility of using alkaline-earth metal hydroxide nanoparticles in the deacidification process. Much of the research to date was conducted with nanoparticles with sizes in the range of 50–100 nm (Gorgi et al. 2005, Poggi et al. 2010, Poggi et al. 2014). Such particle sizes seem sufficient for the penetration into voids between fibres and even into cell lumens, the diameter of which after pressing a sheet of paper in a papermaking machine can vary from a few to about a dozen μm. However, for the deacidification process to be effective, deacidifier particles should reach the molecular level of cellulose, and the size of nanoparticles used should be close to the size of microfibrils (25–40 nm in width) and macrofibrils of cellulose (40–80 nm in width) (Jablonsky et al. 2015). The present paper describes the results of studies investigating the efficiency of penetration of magnesium hydroxide nanoparticles into the structure of artificially acidified model papers.

305

MATERIALS Nanoparticles of Mg(OH)2 (p.a. grade, Aldrich, No. 632309) with particle size <100 nm were used as the deacidifying agent. The aqueous dispersion of nanoparticles had the pH of 10.60. For reasons of chemical purity the model paper used in the present study was Whatman 3Chr MM chromatography paper with a grammage of 180, 0.35 mm thick, made from cotton fibres containing 98% of α-cellulose. The starting pH level (cold water extract) of the paper was 7.36. The paper was cut into samples measuring 4 × 4 cm. The samples were acidified using H2SO4 solution with a pH level of 2.07 until the cold water extract of the paper achieved the pH of 4.55. The samples were then dried between sheets of blotting paper and left at room temperature for 10 days until dried out. Magnesium traces (<5 ppm) in the paper were analyzed by AAS. SEM-EDX and XPS spectra of reference samples (non-acidified and acidified paper) showed no presence of magnesium and sulphur on the sample surface. Some paper samples were not artificially acidified with H2SO4, but briefly immersed in iron gall ink and immediately taken out. The samples were dried and then deacidified similarly to the samples which were artificially acidified with sulphuric acid. Iron gall ink was prepared according to the method proposed by Neevel (Neevel 1995). After determining the moisture content the samples were deacidified by means of a dispersion of Mg(OH)2 nanoparticles in 2-propanol. The analyses were carried out with solutions at concentrations ranging from 0.0125% to 1.2%. After mixing the suspension with a magnetic stirrer (5 min), Mg(OH)2 was introduced into the paper using a washing method. The samples were placed in Petri dishes, filled with a dispersion and left for 0.5 h. As the next step, they were turned over and deacidified for another 0.5 h. When the deacidification process was complete, the paper samples were again placed between sheets of blotting paper and pressed with a sheet of neutral cardboard (pressure force: 1.2 g/cm2) to achieve an even surface. The analyses were performed on paper samples 10 days after the completion of the deacidification process, subjected to artificial ageing at a temperature of 80°C and RH of 65% for 5 hours. The efficiency of acidification and deacidification of paper samples was controlled by determining the pH value of the aqueous extract (cold water) according to the Tappi T 509 om-02 standard. The pH tests were carried out 10 days after the application of Mg(OH)2 dispersion by means of an Elmetron CP 401 pH-meter with an accuracy to ±0.01. All the tests were performed with p.a. grade reagents and deionized water. The efficiency of magnesium hydroxide penetration was assessed by a scanning microscope (LEO Electron Microscope 1430 VP). The analysis was performed with samples sputtered with a gold layer (microscope with a SE [Secondary Electron] detector). Qualitative and quantitative analyses of magnesium on the surface of samples were also carried out with an EDX (Energy Dispersive X-ray) spectrometer (Quantax 200) and XFlash 410 detector (BrukerAXS ). Samples for assessing the penetration of nanoparticles into the paper were prepared by two methods: cutting with a scalpel at the cross-section and fibre removal by peeling off adhesive tape ten times from the paper sample surface.

RESULTS The results of pH analyses of aqueous extracts from deacidified paper samples (Table 1) show that at least some acids contained in the paper become neutralized and a part of nanoparticles of Mg(OH)2, which is very sparsely soluble in water, are transferred into the solution and give it an alkaline reaction. Data listed in Table 1 also demonstrate that an increase in the content of Mg(OH)2 in the deacidifying dispersion induces not only an increase in the pH level of paper but also in the degree of polymerization (DP) of cellulose. Similar results were obtained for paper samples covered with acidic iron gall ink. Iron gall ink has a

306 particularly corrosive effect on historical papers. Strongly acidic iron gall inks intensify the process of cellulose hydrolysis. Their constituent Fe ions from iron salts can undergo Fenton reactions to produce reactive free radicals, thus contributing to further paper degradation.

Magnesium hydroxide as a polar compound introduced in a mildly polar solvent (2- propanol) does not form a true solution but – as a result of solvation – it may form a dispersion. A polar solvent promotes the swelling of cellulose fibres – hence magnesium hydroxide nanoparticles should penetrate more efficiently into the porous structure of paper, including individual constituent fibres.

Table 1. pH and DPvisc of paper samples after deacidification with Mg(OH)2 and thermal ageing Concentration of Mg(OH) in dispersion (%) Samples 2 Reference 0.0125 0.025 0.05 0.1 pH after deacidification and ageing (cold water extract)

7.36 8.46 9.08 10.22 10.54 Paper not covered with iron gall ink 3 DPvisc (cm /g)

577.8 386.8 450.3 496.6 520 Paper covered with 139.6 189.2 238 245.8 251.8 iron gall ink

In order to gain insights into the distribution of magnesium compounds in paper after the process of deacidification, microscopic analyses (SEM-SE) were conducted. Microscopic images (Fig 1) show differences in paper surface coverage resulting from the application of various dispersion concentrations. Following deacidification performed using a dispersion at a concentration of 1.2%, significant deacidifier deposits were seen on the paper surface. Microscopic images at a larger magnification show, however, that magnesium compounds fail to form a continuous film-like structure on the paper surface. Structures observed at magnifications of up to 80 000 × are agglomerates of magnesium compounds varying in size from micro- to nanometric dimensions. Considering the fact that the mean pore size in paper ranges from 400 to 800 nm, it can be inferred that a certain amount of nanoparticles are able to penetrate into the paper structure. A comparison of SEM-EDX images (Fig. 2 ) obtained before and after the removal of fibres from the superficial layers of paper reveals that during the process some magnesium compound particles indeed infiltrated into the paper structure. Results of quantitative analysis of the surface of samples performed by SEM-EDX before and after the removal of fibres from the superficial layers (Table 2) show a decrease in the amount of magnesium compounds which are present more deeply, under the surface of papers. What this indicates is, principally, the superficial nature of the deacidification process.

307

Figure 1. SEM-SE images of deposits on paper surface after deacidifying washing with 0.0125% and 1.2% Mg(OH)2 dispersion in 2-propanol.

Although pH analyses performed for aqueous extracts from acidic papers suggest that dispersions of magnesium hydroxide nanoparticles effectively deacidify paper, it remains an open question whether all acid particles which are present – or arise due to SO2 absorption from the air – in internal paper layers (particularly fibre cell walls) are effectively neutralized.

Table 2. Mg content (SEM-EDX) on the surface and in internal layers of Whatman papers deacidified with Mg(OH)2 nanoparticles: dispersion concentration 1.2% Paper sample Mg content (At%) Surface 1.16 Internal layers 0.63

Figure 2. SEM-EDX images of magnesium compounds on the surface (left) and in internal parts of paper (right): 1.2% Mg(OH)2 dispersion in 2-propanol.

ACKNOWLEDGEMENT This study has been realized with the financial support of National Science Center (Poland) grant No. DEC-2012/05/B/HS2/03999.

REFERENCES

1. SOBUCKI W., 1999: Odkwaszanie zabytkowych i niezabytkowych papierów, Przegląd Papierniczy 55(11); 749–752 2. STRLIČ M., KOLAR J., 2002: Cultural heritage research: a Pan-European challenge. Proceedings of the 5th EC conference, Cracow, Poland; 79-85. 3. BATY J.W., MAITLAND C.L., MINTER W., HUBBE M.A., JORDAN-MOWERY D.K., 2010: Deacidification for the conservation and preservation of paper-based works: a review, BioResources 5(3); 1955-2023 4. GIORGI R., BOZZI C., DEI L., GABBIANI C., NINHAM B., BAGLIONI P.,2005: Nanoparticles of Mg(OH)2: Synthesis and application to paper conservation, Langmuir 21(23), 8495 - 8501

308 5. POGGI G., GIORGI R., TOCCAFONDI N., KATZUR V., BAGLIONI P., 2010: Hydroxide nanoparticles for deacidification and concomitant inhibition of metal-gall ink corrosion of paper, Langmuir 26(24), 19084 – 19090 6. POGGI G., TOCCAFONDI N., MELITA L.N., KNOWLES J.C., BOZEC L., GIORGI R., BAGLIONI P., 2014: Calcium hydroxide nanoparticles for the conservation of cultural heritage: new formulations for the deacidification of cellulose- based artifacts, Applied Physics A, 114; 685 - 693 7. JABLONSKÝ M., VIZÁROVA K., KAZIKOVÁ J., FEKETE R., KASKÖTÖ M., TIŇO R., KATUSČÁK S., 2016: Dajú sa knihy deacidifikovať vodnými procesmi? Zbornik Prispevkov z Konferencie CSTI 2015 Conservation Science, Technology and Industry, FCHPT STU, SNM, Bratislava; 87 - 94 8. NEEVEL J.G., 1995: Phytate: A potential conservation agent for the treatment of ink corrosion caused by iron gall inks, Restaurator 16; 143 - 160.

Streszczenie: Indywidualne odkwaszanie papieru dyspersją nanocząsteczek wodorotlenku magnezu w alkoholu: problem efektywności procesu. Celem pracy była ocena efektywności odkwaszania papieru wodorotlenkiem magnezu o nanometrycznych rozmiarach cząsteczek. Stosowano pomiary pH wyciągów wodnych z papieru, oznaczenie SP celulozy zarówno dla papierów sztucznie zakwaszonych jak i pokrytych atramentem żelazowo-galusowym oraz mikroskopię skaningową z przystawkami SE i EDX. Analizy wykazały, że nanocząsteczki umożliwiają uzyskanie alkalicznych odczynów wyciągów wodnych i ograniczenie degradacji celulozy, co utożsamiane jest ze skutecznością zabiegu. Depozyty związków magnezu występują po odkwaszaniu głownie na powierzchni próbek, ale część nanocząsteczek wnika również w wolne przestrzenie wewnątrz papieru.

Corresponding author:

Adam Wójciak Poznan University of Life Science, Institute of Chemical Wood Technology, ul. Wojska Polskiego 38/42 60-637 Poznan, Poland e-mail: [email protected], phone: +48 61 848 74 53,

309 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 310-314 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Practical screw withdrawal strength in chosen wood-based composites

MARCIN WOŁPIUK, MACIEJ SYDOR Poznan University of Life Sciences, Faculty of Wood Technology, Department of Woodworking Machines and Fundamentals of Machine Design

Abstract: Practical screw withdrawal strength in chosen wood-based composites. The study presents results of tests on the holding capacity of screws mounted in wood-based materials, i.e. particleboard and MDF, using universal and euro screws. Tests were conducted in order to determine practical screw holding capacity, causing no permanent deformation or damage to board structure. In order to conduct tests consisting in axial pullout of screws the limit of proportionality of the system was determined, on the basis of which practical screw retention capacity was identified.

Keywords: screw pullout, screw withdrawal strength, load-bearing capacity, particleboard, MDF.

INTRODUCTION Screws for wood-based materials are used to connect elements in a great variety of structures (furniture, structural elements of buildings, street furniture, etc.). They may also be used to attach various subassemblies, e.g. furniture joints, handles, rails, hinges, etc. In technology many structural types of screws are used, differing in the material, outer layer, dimensions and shape. In furniture industry universal screws are used, particularly to attach various types of furniture fittings, as well as produce furniture connectors of limited loadbearing capacity. Another popular screw type is the Euro screw. Such screws are used to assemble elements bearing low loads, i.e. door hinges or drawer rails, mounted in elements made mainly from particleboards. These screws, thanks to their design, are adapted to bear very high loads. Thread geometry of Euro screws is identical to that in Confirmat screws, commonly used to connect furniture structures bearing considerable loads. None of these screws are standardised and thus the so-called de facto standards are adopted by many manufacturers in various branches of industry (Sydor, 2016). Regardless of the fact whether the screw is an independent connector or whether it is used as a locking element of another structural subassembly, its important property is connected with the capacity to counter the axial pullout force. A measure of this capacity is provided by the value of the force required to overcome resistance of wood-based material at pullout of the connector in the direction of its longitudinal axis (PN-EN 320:2011, n.d., p. 2011). Many studies have been conducted on the retaining force for screws in wood and wood-based materials. Results were dependent on the type of wood-based material, its physical and mechanical properties, size, sample shape, diameter of the pilot hole, connector type, orientation of mounting in the sample, as well as pullout rate (Fairchild, 1926; Rajak & Eckelman, 1993; Biniek, 1994; Eckelman, 1988; Erdil & Zhang, 2002; Gates, 2009). In most cases the rupture force of a threaded connector is assumed to be the maximum force recorded in the process of screw pullout. However, in reality connection failure occurs much earlier, starting from the moment, when the tested system ceases to be elastic. At that time the first irreversible changes take place in board structure, resulting from microcracks, upset and deformations of material within the joint thread. Experiments consisting in the axial screw pullout usually provide a dependence of pullout force in the function of screw pullout from the hole (fig. 1). In the stress–strain graph we may observe a characteristic point of deflection defining the maximum screw retaining force (Fmax). We may distinguish a simple section running between points GPmin and GPmax defining the

310 range of elasticity of the system of a screw mounted in the board (fig. 1.). Point GPmin corresponds to the beginning of the range of proportionality, while point GPmax is the end of the range of proportionality (the upper limit of proportionality).

Figure 1. The course of screw pullout

MATERIALS AND METHODS Experiments conducted within this study consisted in the determination of retention capacity for universal screws and Euro screws mounted in narrow and wide planes of particleboard and fibreboard (MDF) of 18 mm. Tests were conducted on the Zwick Z050 universal strength testing machine (fig. 2).

Figure 2. The testing station

311 Samples of 50×50×18 mm were cut from the central part of sheets for each board. Next in centrally located points of the wide and narrow plane for each sample pilot holes were drilled to a depth of 15 mm with dimensional accuracy of ± 0.5 mm. The diameter of these holes was equivalent to the shank of the mounted screw. Pulled-out universal screws were 4×40 mm, while for Euro screws it was 6.3×20 mm. Both tested connectors were screwed in to a depth of 15 mm. Eight tested systems were obtained, in which variables included board type (particleboard vs. MDF), screw type (universal vs. euro) and the direction of joint mounting in the board (narrow vs. wide planes). A total of 9 replications were performed for each tested system, thus providing 72 samples. Connectors were pulled out at a rate of 1 mm/min.

RESULTS The results provided a dependence of the value of the pullout force in the function of screw detachment. Values of the retaining force were read at the upper limit of proportionality (GPmax) and at maximum stresses at the sample failure point (Fmax). Table 1 lists values of pullout force (N) in relation to screw-in depth (cm).

Table 1. Screws holding ability Screws holding ability

Badany układ in the limit of proportionality total load bearing capacity difference

Zwgw S v Zwmax S v Zw Zw

Board / Screw / Surface N/cm N/cm % N/cm N % N/cm %

Chipboard / Universal / Narrow (CUN) 196 26 14 308 43 14 112 36

Chipboard / Universal /Wide (CUW) 275 62 23 451 34 7 176 39

Chipboard / Euro / Narrow (CEN) 340 49 14 483 49 10 143 30

Chipboard / Euro / Wide (CEW) 433 42 10 643 43 7 210 33

MDF / Universal / Narrow (MUN) 606 35 6 711 36 5 105 15

MDF / Universal / Wide (MUW) 526 65 12 776 67 9 250 32

MDF / Euro / Narrow (MEN) 827 104 13 1059 73 7 232 22

MDF / Euro / Wide (MEW) 822 125 15 1101 47 4 279 25

The graph given in Figure 3 presents screw retaining capacity taking into consideration values found in the upper limit of proportionality. The graph presents standard deviations for measurements recorded in this study.

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0 CUN CUW CEN CEW MUN MUW MEN MEW

in the limit of proportionality total load bearing capacity

Figure 3. Screw holding capacity depending on the tested system

The graph given in Figure 4 presents a percentage share of screw retaining capacity within the range of proportionality of the system in relation to the total load bearing capacity of a given connector.

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20%

0% CUN CUW CEN CEW MUN MUW MEN MEW

in the limit of proportionality total load bearing capacity

Figure 4. The share of the value of upper limit of proportionality in screw retaining capacity.

DISCUSSION From the point of view of designers the actual load bearing capacity of threaded connections is crucial. Reliability of the connection defined by the screw retention capacity in board material, measured in apparent strength of the connector, is to a considerable degree incorrect, while outside the upper limit of proportionality the system is exposed to irreversible stuctural changes in the board resulting from the reduction in screw retention capacity. It results from the conducted tests that screw retention capacity is directly dependent on the type of wood-based material, dimensions and geometrical shape of the connector as well as the site of its mounting in the board (narrow vs. wide plane). Irrespective of the analysed system (board/screw/mounting plane) practical screw retention capacity described for the upper limit of proportionality is above the safe threshold of 60% maximum load bearing capacity. Loading

313 of threaded connections with such values obviously does not cause permanent deformations or failure of the connection.

CONCLUSIONS • Screw holding capacity depends on the type of the connector, board and direction of connector mounting in the board, • Practical screw retention capacity in wood-based materials is approx. 60% apparent strength.

REFERENCES 1. Biniek, P. (1994). Badania porównawcze zdolności utrzymania wkrętów o tych samych parametrach wymiarowych mocowanych w drewnie i tworzywach drzewnych. Przemysł Drzewny, 45(9). Retrieved from www.przemysldrzewny.eu 2. Eckelman, C. (1988). The withdrawal strength of screws from commercially available medium density fiberboard. Forest Products Journal, 38(5), 21–24. 3. Erdil, Y. Z., & Zhang, J. (2002). Holding strength of screws in plywood and oriented strand board. Forest Products Journal, 52(6), 55. 4. Fairchild, I. J. (1926). Holding power of wood screws. US Government Printing Office. 5. Gates, J. C. (2009). Screw withdrawal strength in 9Wood’s Assemblies. Oregon Wood Innovation Center, Test Evaluation Report. Retrieved from http://www.9wood.com/files/rd_reports/screw_withdrawl.pdf 6. PN-EN 320:2011. (n.d.). (No. Płyty wiórowe i płyty pilśniowe-- Oznaczanie oporu przy osiowym wyciąganiu wkrętów [Particleboards and fibreboards. Determination of resistance to axial withdrawal of screws]). 7. Rajak, Z. I. B. H. A., & Eckelman, C. A. (1993). Edge and face withdrawal strength of large screws in particleboard and medium density fiberboard. Forest Products Journal, 43(4), 25–30. 8. Sydor, M. (2016). Innowacje w zakresie łączników gwintowych do tworzyw drzewnych. Fastener. Rynek Elementów Złącznych (Dodatek Do STAL Metale& Nowe Technologie), (1/2016), 35–38.

Streszczenie: Praktyczna odporność na wyrywanie wkrętów w tworzywach drewnopochodnych W pracy opisano wyniki badan nad zdolnością utrzymywania wkrętów osadzonych w tworzywach drewnopochodnych takich jak płyta wiórowa i płyta MDF, do badań użyto wkrętów uniwersalnych oraz wkrętów typy EURO. Badania prowadzono pod kątem określenia praktycznej zdolności utrzymywania wkrętów, niewywołującej trwałych odkształceń i zniszczeń struktury płyty. W wyniku badań eksperymentalnych polegających na wyrywaniu osiowym wkrętów określono granicę proporcjonalności układu, na podstawie której oznaczono praktyczną zdolność utrzymywania wkrętów.

Corresponding author: Marcin Wołpiuk, ul. Wojska Polskiego 38/42 60-627 Poznań email: [email protected] phone: (061) 846-6144

314 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 315-323 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

A review of failure mechanisms in joints of wood-based boards

MARCIN WOŁPIUK, MACIEJ SYDOR

Poznan University of Life Sciences, Faculty of Wood Technology, Department of Woodworking Machines and Fundamentals of Machine Design

Abstract: A review of failure mechanisms in joints of wood-based boards. The paper presents an optical analysis of the damage zone in threaded connections. The analysis of reinforced connectors makes it possible to assess the quality of interlocking connectors of a universal screw with a board, in order to facilitate design of improved structural solutions in the future. Assessment included images of the damage zone in reinforced and non- reinforced particleboard and MDF following measurements of screw retention capacity. We observed a dependence of the size of the damage zone on the type of wood-based material, the direction of connector mounting as well as the application of local reinforcement.

Keywords: screw pullout, joint failure images, local board reinforcement

INTRODUCTION

Structural nodes of modern furniture are typical interlocking connectors composed of joints of various structural designs. Joints are usually commercially manufactured, metal or plastic multi-element precision engineering products. A schematic model of a structural node of two board elements is given in figure 1. The most popular form of locking elements in various connector types includes threaded screws, i.e. connectors with the external thread, automatically forming the internal thread in the joined board. These screws may be screwed in directly (self-drilling screws) or mounted into pre-drilled pilot holes. A measure of load- carrying capacity for such interlocking connectors is their capacity to counter the axial screw pullout force.

315

Figure 1. A model of a structural node of two wood-based boards and a connector (based on (Sydor, 2005)) A model of loading for a typical structural node of two boards is presented in fig. 2.

M PR Θ

≈ g/2

Figure 2. A simplified mechanical model of an angle joint The structural node is loaded with bending moment M. As a result the locking element of the connector (e.g. a screw) is loaded with pullout force F. An example of a connector with four locking elements (screws) is presented in fig. 3.

316 b) a) (1) body

(2) rail (3) screw (4) body mounting screw

Figure 3. A connector with a trapezoid joint: a) trapezoid joint, b) mounting of the joint in the connector (source: (Sydor, 2005)) In the connector with a trapezoid joint presented in fig. 3, two screws are placed in each board. As a result of the bending moment causing separation of the connector the structural node was destroyed as a consequence of two screws being pulled out (fig. 4). By analysing failure zones we may assess quality of the interlocking connection between the screw and the board, which will facilitate designing of an improved structural solution.

Figure 3. A example image of failure of a connection of partcileboards using a trapezoid-shaped joint (source: (Sydor, 2005)) MATERIALS Since the load-bearing capacity of a thread connection between a metal screw and the mated screw cap determines board strength (Sydor, 2005; M. Wołpiuk & Sydor, 2009; Marcin Wołpiuk, 2015; Sydor & Wołpiuk, 2016), it was decided to conduct a comparative analysis of failure types at axial pullout of screws from a locally reinforced board and analogous failure for non-reinforced board. In this study it was decided to assess visually the sites of board failure generated as a result of screw pullout. For this purpose selected destroyed samples were photographed after

317 screw retention tests. Damage zones of non-reinforced boards and those of boards, in which local reinforcement was applied, were compared for the system of a universal screw mounted in particleboard and MDF in the wide and narrow surfaces. Photographs were taken with a digital camera. They were set to present screws in the horizontal and vertical positions, making it possible to assess the failure zone. Local increase in strength properties of boards was provided by the application of PUR 555.6, a polyurethane preparation reinforcing board structure, by Kleiberit. The volume of the preparation was established on the basis of the multiple of the volume of a thread in the 4×40 mm universal screw and the depth of its mounting in the board (15 mm). Failure zones were analysed in non-reinforced samples and in samples reinforced with an 8-fold volume of the joint thread. The reinforcing agent was applied in the previously drilled pilot holes with the diameter of the screw shank, while joint retention capacity was measured 72 hours after application.

RESULTS Tables given below (tab. 1–4) present images of failure, which were divided in terms of the type of wood-based material and the direction of connector mounting. In order to provide a more comprehensive picture of the discussed damage two different images of a given system were taken. Results were arranged in terms of the screw–board system. Table 1 presents the effect of pullout of a universal screw mounted perpendicularly to the surface of the particleboard. On the left the system without local reinforcement of the board is given, while on the right the presented system is composed of the board locally reinforced with 8 application units.

318 Table 1. Effects of pullout of a universal screw from the wide surface of particleboard

Image Non-reinforced board (Zw = 459 N) Locally reinforced board (Zw = 903 N)

ZW – withdrawal strength

A visible effect of reinforcement is the 3-fold increase in the damage zone of the board. This results from the fact that the reinforced internal layers of the board transfer stresses over a larger area of the face layer and the result is a much greater screw retaining force.

Table 2 presents the effects of pullout of a universal screw mounted in the narrow surface of the particleboard. On the left we present images of the connection of a screw with a commercially available, non-reinforced board, while on the right the effects of pullout are given for a screw from a board locally reinforced with PUR 555.6, applied as 8 application units. In the case of the locally non-reinforced board the pulled-out joint is surrounded by the damage zone adjacent to the thread, consisting of single chips broken from the board core. In turn, in the locally reinforced board the damage zone is 3-fold greater and its characteristic feature is that here it is not single fibres mated with the screw thread that are pulled out, but it is a part of the entire reinforced core with the width of the pulled-out joint, thanks to which

319 the screw retention capacity is increased 3-fold. The pulled-out section of the board exhibits considerable cohesiveness and hardness.

Table 2. Effects of pullout of a universal screw from the narrow surface of particleboard

Image Non-reinforced board (Zw = 308 N) Locally reinforced board (Zw = 928 N)

ZW – withdrawal strength

Table 3 presents images of failure for samples of MDF connections with a universal screw mounted perpendicularly to the wide surface of the board. The table compares a non- reinforced sample and a sample locally reinforced with 8 application units. It results from the data given above that the damaged area in the case of locally reinforced MDF is approx. 2-fold greater than in the case of non-reinforced board. Cracks in the face layer of the reinforced board spread from the board surface as large stiff flakes. In turn, in the non-reinforced board the surface of the face layer deflects, next it breaks and crumbles in the zone adjacent to the screw.

320 Table 3. Effects of pullout of a universal screw from the wide surface of MDF

Image Non-reinforced board (Zw = 776 N) Locally reinforced board (Zw = 1661 N)

ZW – withdrawal strength

Table 4 presents images of pullout of a universal screw from the MDF narrow surface. A difference in the MDF failure zone was seen in images presented in Table 4. Damage to the non-reinforced board is of limited size and it is adjacent to screw threads. Pulled-out wood fibres are broken and come from the space between threads of the removed joint. Board structure outside the connector area is undamaged. In the case of the locally reinforced board the damage zone is many times greater than in the in non-reinforced board. The pullout process consists in truncation of a compact structure within the internal zone. Failure is of the width of the tested connector with the wedge-shaped transverse section. The pullled-out part of the board shows considerable cohesiveness and hardness in contrast to the part pulled out from the board with no local modification applied.

321 Table 4. Effects of pullout of a universal screw from the narrow surface of MDF

Image Non-reinforced board (Zw = 711 N) Locally reinforced board (Zw = 1615 N)

ZW – withdrawal strength

The images presented above show that local reinforcement of wood-based boards may be characterised using failure images of the connection. An increased damage zone is manifested in the much greater screw retention capacity.. In non-reinforced samples, where the screw is mounted in the narrow board surface without any prior application of PUR 555.6, we observe truncation of the thread pressed by the joint in the wood-based material along with a slight bulge of the adjacent area. In the case of screws mounted perpendicularly to the wide surface of non-reinforced samples, the board was markedly delaminated at joint pullout. It may be assumed that truncation of the thread pressed in the board does not occur followed by disruption of the board in the direction, in which the worst tensile strength properties are observed and next individual impressed threads slide from joint threads. In the case when a screw is mounted in the wide board surface the damage zone resembles roughly a reversed cone. Stresses caused during joint pullout exert pressure on successive board layers starting from the first thread on the screw progressing towards the board surface. Local modification increases the area of the cone base in view of the potential transfer of stresses by the reinforced part of the structure in the board core. For screws mounted in the narrow surface of the board, the damage zone also increases with an increase in screw retention caused by local reinforcement of the wood-based material. In this case the damage zone roughly resembles a prism, which height is the depth of screw mounting in the board, the width corresponds to the depth of damage and thickness is equivalent to the diameter of the pulled-out connector. Failure is characterised by truncation

322 of the material within the board core and its separation from sites of lesser strength and cohesion. CONCLUDING REMARKS The undertaken experiments consisted in the identification of the effects of rupture forces exerted on the reinforced connection while screws are being pulled out. The effects of rupture forces are presented as images of failure of example connections of a screw with a board. As a result of these analyses the following conclusions were formulated: • Stresses caused by connector pullout thanks to reinforcement are transferred to the board layers more distant from the screw. It resulted in an extension in the zone retaining the screw in the board – as a result of which the force required to pull it out is also increased. An increase in the retaining force and an extension of the zone actively retaining the screw cause an increase in the area of the load bearing zone, which is advantageous for load-bearing capacity of the connection. • Damage is observed mainly at the interface of the reinforced zone, since non-reinforced layers of both particleboard and MDF are not capable of transmitting equally large loads as reinforced board layers. Damage to the connections of screws mounted in the narrow surface of boards is most frequently truncation of the board core adjacent to the screw. Damage to the system with the screw mounted in the wide surface of the locally reinforced board consists in truncation of layers adjacent to the first thread of the screw, followed by the internal, strong pressure on the external board layer, causing its detachment as a result of board delamination. REFERENCES 1. Sydor, M. (2005). Właściwości konstrukcyjne półsztywnych kątowych połączeń płyt drewnopochodnych ze złączami (eng. Construction properties of semi-rigid joints of wood-based boards with fasteners) (Rozprawa doktorska/PhD thesis). Poznan University of Technology. Faculty of Wood Technology, Poznań. Retrieved from http://depot.ceon.pl/handle/123456789/641 2. Sydor, M., & Wołpiuk, M. (2016). Analysis of resistance to axial withdrawal of screws embedded in locally reinforced MDF. Drewno, 59(196), 173–182. http://doi.org/DOI: 10.12841/wood.1644-3985.093.14 3. Wołpiuk, M. (2015). Badania nad zdolnością utrzymania wkrętów w lokalnie wzmocnionych płytach drewnopochodnych (eng. Research on the screws holding ability in locally strengthened wood-based panels) (Rozprawa doktorska/PhD thesis). Poznan University of Technology. Faculty of Wood Technology, Poznań. 4. Wołpiuk, M., & Sydor, M. (2009). Constructional properties of connected wood- derived panels and strength design of hardware joints. Annals of WULS, Forestry and Wood Technology, (69), 446–449.

Streszczenie: Przegląd mechanizmów zniszczeń połączeń płyt drewnopochodnych. W pracy podjęto się analizy optycznej strefy zniszczenia połączeń gwintowych. Przeprowadzona analiza wzmocnionych połączeń pozwoliła ocenić jakość połączeń kształtowych wkrętu uniwersalnego z płytą, by w przyszłości umożliwić zaprojektowanie lepszych rozwiązań konstrukcyjnych. Ocenie poddano obrazy strefy zniszczeń wzmocnionej i niewzmocnionej płyty wiórowej oraz MDF po uprzednio wykonanych pomiarach zdolności utrzymywania wkrętów. Zaobserwowano zależność wielkości strefy uszkodzenia od rodzaju tworzywa drewnopochodnego, kierunku osadzenia łącznika, a także od zastosowania lokalnego wzmocnienia.

Corresponding author: Marcin Wołpiuk, ul. Wojska Polskiego 38/42, 60-627 Poznań email: [email protected], phone: (061) 846-6144

323 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 324-327 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Experimental testing of a selected furniture joint

VLADIMÍR ZÁBORSKÝ, DANIEL RUMAN, VLASTIMIL BORŮVKA, MILAN GAFF

Department of wood processing Faculty of forestry and wood sciences, University of Czech University of Life Sciences in Prague, Kamýcká 1176, Praha 6 - Suchdol, 16521 Czech Republic;

Abstract: Experimental testing of a selected furniture joint. The main focus of this article is the verification of the elastic stiffness of a selected furniture joint under compressive stress. The joint is a glued spatial corner joint with a non-continuous haunched tenon. The joint was glued with polyvinyl acetate glue. Keywords: furniture joint, joint stiffness, bearing capacity of joint, tenon, mortise

INTRODUCTION The most common type of joint used in construction elements is the mortise and tenon joint. This joint is usually glued. The mortise and tenon joint must be made with minimum tolerance in order to ensure the joint strength. The highest joint strength is ensured when the adhesive is applied to the tenon as well as the inside of the mortise (Terrie, N. 2009). In his article, Smardzewski (2002) examined the distribution of shear stress at the joint using PVA adhesives. Konnerth et al. (2006) examined the behavior and durability of a joint from beech and spruce wood glued with PVA glue, and compared it with other types of adhesives. He found that the shear bond strength of the glued joint made of beechwood was 25% higher than in spruce wood. The effect of the type of adhesive used on the shear bond strength of the joint was not statistically significant. The use of thermoplastic PVA glues is common in furniture production, were they are used to bond products. PVA glue first appeared in 1950, and it replaced natural adhesives. These adhesives are not harmful to human health or the environment (Mitani and Barboutis 2010). The advantage of adhesive bonding is its versatility and lower cost in comparison to other bonding means.

MATERIALS For the experiment we used the wood species (Fagus sylvatica L.). Planks with a 52 mm thickness were cut from the logs. The planks were acclimatized to an equilibrium moisture content of 8% in a climatic chamber with the following environmental conditions: relative humidity of 40% and temperature of 20°. The moisture content of 8% corresponds to the equilibrium moisture content of interior elements pursuant to ČSN 91 0001 (2007). Subsequently, dimensional lumber was created by slant-cutting, the shape and structure of which was treated to create various parts of the construction joint, according to construction documentation. Figure 1 shows the stile with mortises and Figure 2 shows the rail with a non- continuous haunched tenon. Glue was applied to the mortises and tenons of the joint in accordance with the technical data sheet for the glue AG-COOL 8761/L D3, and the entire structure joint was assembled and clamped with table clamps in the prepared device.

324

Figure 1. Illustration of stiles Figure 2. Illustration of rails

Figure 3 shows the schematic of compressive loading of the test sample, using the testing device UTS 50 (Germany). 10 test samples were tested

Figure 3. Experimental testing

The elastic stiffness was evaluated according to the equation C=∆M/∆y, where ∆M represents the torque change (Nm) and ∆y represents the angle change in °.

325

RESULTS

Table 1. Table of average data type of type of force force distance distance change in change Elastic loading adhesi 10% in 40% in 10% in mm 40% in torque in in stiffness ve N N mm Nm angle in in ° Nm/rad pressure pvac 74,85 298,35 1,35 4,97 29,55 1,55 1092

Figure 4 shows a force-deformation diagram from the selected test. The average density of the samples calculated at 12% is 705 kg/m3. This value, which is comparable to Wagenführ's (2000) result, indicates the density of beechwood (Fagus sylvatica L.) at a 12% moisture content of 720 kg/m3.

Figure 4. Force-deformation diagram Figure 5 shows the failure of the spatial joint by a partially cracked stile.

Figure 5. Sample failure

326 This research focused on the verification of the method based on which other types of joints of different sizes will be experimentally tested. The chosen method is suitable for the selected types of spatial structure joints.

REFERENCES

1. TERRIE, N. 2009: Joint Book: The Complete Guide to Wood Joinery, Chartwell Books, 192 p. 2. SMARDZEWSKI, J. (2002). “ Technological heterogeneity of adhesive bonds in wood joints,“ Wood Science and Technology 36, pp. 213-227. 3. KONNERTH, J., WOLFGANG, G., HARM M., MULLER U., (2006). ”Comparison dry strength of spruce and beech wood glyed with different adhesives by means of scarf- and lap joints testing method,” Holz als Roh- und Werkstoff 64, pp. 269-271, Austria. 4. MITANI, A., and BARBOUTIS, I. (2010). “Shear strength by compression loading of some hardwoods glued with PVAc and casein adhesives,“ First Serbian Forestry Congress, Belgrade University, Faculty of Forestry, Serbia, 11-13 November 2010, pp. 1352-1360. 5. ČSN 91 0001. (2007). “Furniture -Technical requirements,” Czech Office for Standards, Metrology and Testing, Prague, Czech Republic. (in Czech) 6. WAGENFÜHR, R. (2000). Holzatlas, 5th Edition, Fachbuchverlag, Leipzig, Germany (in German), 707 p

Streszczenie: Testy wytrzymałości wybranych połaczeń meblowych. Praca skupia się na veryfikacji sztywności wybranych połączeń meblowych przy ściskaniu. Połączenia były klejone przy pomocy kleju polioctanowinylowego.

Corresponding author:

Daniel Ruman Novohradská 996/8 99 001 Veľký Krtíš [email protected] 00421 902 977 071

327 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 328-334 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Chemical properties, density and alkalinity of the black liquor obtained from kraft pulping of a selected fast growing poplar line and of reference species

JANUSZ ZAWADZKI, FLORENTYNA AKUS-SZYLBERG, OLGA BYTNER, MICHAŁ DROŻDŻEK Department of Wood Science and Wood Preservation, Faculty of Wood Technology, Warsaw University of Life Sciences – SGGW Abstract: Chemical properties, density and alkalinity of the black liquor obtained from kraft pulping of a selected fast growing poplar line and of reference species. Attempts were made to determine the contents of selected chemical components and the major physical properties of the black liquor obtained in the kraft pulping of selected species of trees. For the pulping process the selected 2.5-year-old fast growing poplar varieties were taken and as reference samples use was made of birch, beech, pine and poplar trees. Major chemical properties of black liquor were determined such as solids and minerals contents, and its essential physical properties such as density and alkalinity were examined. The results obtained were found to depend largely on the concentration of the pulping alkalis employed in the wood pulping process. Keywords: poplar tree, black liquor, solids content, mineral components, density, alkalinity

INTRODUCTION In our times the commercial process that enjoys considerable popularity as the cellulose pulp manufacturing method is the sulfate process alternatively known as the kraft process. Employed in the process to digest biomass are sodium hydroxide (NaOH) and sodium sulfate (Na2S) solutions. The supremacy of this process stems from its versatility, but likewise from the fact that the pulp derived features a good quality, combined with a highly effective chemicals recovery and heat recovery system (Sjöholm, 1999; Przybysz, 2007). During the manufacture of paper grade pulp a byproduct, known as black liquor is formed. Black liquor contains a number of components (Sjöström and Alen 1999). Of the most significant are lignin, aliphatic carboxylic acids, referred to as other organic compounds that include extractive components and polysaccharides. Inorganics account for a large part of black liquor. These compounds to date have been used to a minor degree. Improved procedures in the black liquor analysis may become of significance for the prospective utilization of this material. The purpose of this study was to examine the density and alkalinity of the liquor and the contents of the selected chemical components (solids and mineral ingredients) in the black liquor formed during wood pulping by the kraft process and to determine the density and alkalinity of the liquor.

MATERIALS The liquors were derived in the wood pulping process by the kraft method. For the study 2.5 years old (Populus maximowiczii) and (Populus trichocarpa) poplars were chosen. The trees were taken from the experimental field of the SGGW Gardening, Biotechnology and Landscape Architecture Department in Warsaw. Black liquors were provided by the Łódź Technical University Papermaking and Printing Institute. For wood pulping the following chemicals were used: NaOH and Na2S of a total concentration of 19% or 26%. The digesting

328 temperature was 160oC. The black liquors from pulping of other tree species were also investigated as reference samples. Specifically, black liquors from poplar (Populus L.) pulping produced at alkali concentrations of 19, 20, 22, or 26% and a temperature of 160oC; black liquors from beech (Fagus L.) pulping, of a concentration of 20% and a temperature of 165oC; black liquors from birch (Betula L.) pulping, of a concentration of 20% and a temperature of 165oC; and black liquors from pine (Pinus sylvestris L.) pulping, of a concentration of 22% and a temperature of 172oC. Upon selecting suitable samples for the study the following parameters were determined: solids and mineral substances content (Prosiński, 1984; Krutul, 2002), density and alkalinity with the aid of a Microcomputer pH meter model CP-551 instrument. RESULTS Results of the analysis of the solids content in the black liquors examined are reviewed in figure 1. The solid material is what in normal conditions would remain as a result of the evaporation process. The results report the values ranging from 12.15% to 15.68%. The values reported in the literature for the solids present in black liquors derived from commercial processes range between 14 and 18% (BAT, 2005). The most solids (15.68%) was noted for the beech wood (Fagus L) and the least (12.15%), for the poplar wood (Populus L.). The solids content grows with rising alkali concentration for a given wood kind. For 19% poplar (Populus L.) it equals 12.15%, whereas for 20% poplar (Populus L.) it is 13.00%, for 26% poplar (Populus L.) it is 14.7%. Substantial difference is apparent between 19% and 26% Japanese poplar (12.8% and 13.15%, respectively), and between 19% and 26% Black cotton wood (Populus trichocarpa) poplar (12.44%, and 13,21%, respectively).

Figure 1. Solids content as determined in the tree species examined (Akus-Szylberg, 2015). This is evidence of a significant effect of the alkali concentration employed in the digestion process on the solids content. For the solids are made of the organic and inorganic components of the wood substance which had passed into the solution by the action of the chemicals, as well as part of the alkalis themselves. Hence the solids content in the liquor depends also on the kind of the wood from which the wood material derived. Moreover, the pulping process parameters had an impact on the values obtained. Results of the analysis of the ash content in black liquors are reviewed in figure 2. The ash represents mineral components of the wood feedstock and the chemical compounds added in the pulping process. The amount of ash in wood is on average 0.4% to 0.6% (Krutul, 2002).

329 The amount of the ash found from the analysis depends on the concentration of the alkalis used just as it results from all of the remaining parameters of the kraft pulping process such as: the temperature, duration, or the amount of the water used. A significant effect of the alkali concentration on the ash content is visible on the example of the poplar wood.

Figure 2. Determination of the minerals content (Akus-Szylberg, 2015). A considerable effect of alkali concentration on the ash content can be seen on the example of the poplar. For the poplar (Populus L.) 19% the mineral matter accounts for 5.1%. For the poplar (Populus L.) 20%, the corresponding amount is already 5.5%, for the poplar (Populus L.) 22%, the respective number is 5.69%, whereas for the poplar (Populus L.) 26%, the percentage is as high as 6.8%.This is the result of a stronger effect of the liquor of a higher alkali concentration on the wood under digesting.The kind of wood used in the process was also of some significance here. The literature reports the ash content values for the birch (Betula L.) as about 0.3%, the beech (Fagus L) 0.5%, the poplar (Populus L) 0.4% for thep pine (Pinus L) 0.4% (Krzysik, 1974, Rowell, 2005). The amount of mineral matters appears to be largely controlled by the quantity of the inorganic compounds present in the black liquor and their decomposition products. Results of the measurements of the density of black liquors are reported in figure 3. For the 11 black liquors examined the density values range from 1.060 to 1.090 g/cm3. The lowest value was found for the poplar (Populus trichocarpa) 19% and the poplars (Populus maximowiczii) 19% (1.061 g/cm3) and the highest value, in the poplar (Populus trichocarpa) 26% (1.087 g/cm3).

330

Figure 3. Results of the black liquor density measurements (Akus-Szylberg, 2015). The concentration of the alkalis used in the pulping process is critical for the quantity of the number of the wood components that pass into solution. The more chemicals are used, the greater part of the lignin becomes separated. A higher concentration of the chemicals is also responsible for a degradation of a greater number of polysaccharides. The number of the components that will pass into the solution affects in turn the black liquor density. The liquor density is also affected by the other pulping parameters such as temperature and the pulping process time. This finding has been proven by a clear difference in the density values for the liquors of the same wood kinds at different pulping parameters. Specifically, the poplar (Populus L.) 19% and the poplar (Populus L.) 20% have the same density of 1.063 g/cm3, the poplar (Populus L.) 22% has 1.064, whereas for the poplar (Populus L.) 26% it is as high as 1.078 g/cm3. The relationship is also manifest for the fast growing poplars. For the Populus maximowiczii 19% the density is 1.061 g/cm3 and already as high as 1.081 g/cm3 for Populus maximowiczii 26%. Analogously for the Populus trichocarpa the density rises from 1.061 g/cm3 for 19% to 1.087 g/cm3 for 26%. The effect of concentration of the white liquor composed of NaOH 3 3 3 (2.13 g/cm ). NaSH (1.79 g/cm ) and Na2S (1.86 g/cm ) is generally apparent. Inorganic compounds typically exhibit higher density as compared to organic compounds; e.g. cellulose (1.56 g/cm3), hemicelluloses (1.50 g/cm3), or lignin (1.40 g/cm3). A greater amount of the inorganics, as well as lignin sodium salts and mercaptans present in black liquor account for the higher density of the liquors of a greater alkalis concentration. Attention should also be called to the differences between the density of the liquors prepared at the same alkali concentration. This is due to the fact that the specific gravity of the liquor also depends on the wood kind used in the pulping process. This is why at a 20% concentration the beech wood (Fagus L) density is 1.065 g/cm3 and the poplar wood (Populus L) and birch wood (Betula L) or at a 22% concentration the pine wood (Pinus L.) density is equal to 1.070 g/cm3 and that of poplar wood (Populus L.) it is 1.064 g/cm3. The value reported in the literature for the African Oil-Palm wood (Elaeis guineensis) digested at a 20% concentration equals 1.03 g/cm3 (Sun and Tomkinson, 2001). The difference may be due to a various lignin content in the wood kinds mentioned which were used as the raw material in the pulp manufacture. For the pine (Pinus L.) the lignin content is equal to ca. 27%, for the beech (Fagus L.) and the birch (Betula L.) ca. 22%.. whereas for the Poplar (Populus L.), is about 20% (Rosiński 1984, Rowell 2005).

331 The results obtained on the alkalinity level are collected in figure 4. As can be seen from the data reported in all of the black liquors examined the pH value is indicative of a highly alkaline character (above 9 pH), which is a consequence of the pulping process conducted in an alkaline solution. The wood raw material itself is slightly acidic (pH from 3.3 to 6.5) (Krzysik. 1974).

Figure 4. Alkalinity of various wood kinds on a pH scale (Akus-Szylberg, 2015).

Results of the determination of the pH value of the pulping solutions for the samples studied are very similar. Most of the results fall between pH 12.0 and 13.3. Merely the pH level in the case of the poplar digested at an alkali concentration of 19% is clearly lower (pH 9.6; the most likely reason for that was that the lye package was broken and the contents was in contact with the CO2 from the air and could have been slowly neutralizing the liquor). Similar discrepancies are noted for the pH values reported in the literature, where the pH values observed for the African Oil Palm (Elaeis guineensis) assume 10.9 (Sun and Tomkinson, 2001) and pH 12.45 (Mohamad Ibrahim and Chuah, 2004). The differences are due to the fact that the pH value of black liquor depends on a great number of factors like the wood material quality, pulping time, and pulping temperature, as well as the amount of water used. The key elements, however, continue to be the quantity of the chemicals used, in other words the sodium hydroxide (NaOH) and sodium sulfide (Na2S) concentrations in the liquor. This is confirmed by the noticeable relationship between the concentration of the alkalis employed in the pulping process and the pH level measured for a given wood kind, as in the case of the poplar wood (Populus L.). The pH value rises with the alkalis concentration from 9.6 for 19% of active alkalis, through pH 12.44 and pH 12.98 for 22% up to pH 13.22 for 26% alkalis and through the air access, as shown by the poplar wood 19% sample.

SUMMARY Results of the study made allow to formulate the following conclusions. The alkalis concentration in the kraft pulping process is of prime significance mostly as concerns the solids content in the black liquor examined, but also, to a certain degree, with reference to the ash (mineral matter) content. Chemical properties of black liquors are strongly dependent on structure of the wood from which the feedstock is derived, in particular on the wood quality. The results of the study obtained indicate that the amount of minerals depends largely on the

332 amount of the inorganic substances contained in the black liquor and of the salts formed as a result of a reaction of white liquor with the organic substances of the wood. Concentration of the alkalis used in the kraft pulping process is also critical to the physical properties of black liquors, such as pH and density. Physical properties are also strongly affected by the sort, age and structure of the wood from which the pulp is gained.

REFERENCES 1. Akus-Szylberg F. 2015: Badanie składu chemicznego ługu czarnego pozyskanego z roztwarzania metodą siarczanową wybranej linii topoli, Praca inżynierska, Warszawa 2. BAT, 2005:. Raport –Najlepsze dostępne techniki, wytyczne dla branży celulozowo- papierniczej http://ippc.mos.gov.pl/ippc/custom/BAT-%20cel_pap.pdf 3. Krutul D. 2002: Ćwiczenia z chemii drewna oraz wybranych zagadnień chemii organicznej, Wydawnictwo SGGW, Warszawa 4. Krzysik F. 1974: Nauka o drewnie, Państwowe Wydawnictwo Naukowe, Warszawa 5. Prosiński, S. 1984: Chemia Drewna. PWRiL, Warszawa 6. Przybysz, K. 2007: Technologia papieru, cz. 1. Papiernicze masy włókniste, Łódź 7. Rowell R.M. 2005: Handbook of wood chemistry and wood composites, CRC Press, Boca Raton 8. Sjöström, E., Alen, R. 1999: Analytical Methods in Wood Chemistry, Pulping, and Papermaking, Series: Springer Series in Wood Science. 9. Sjöholm E. 1999: Characterisation of Kraft Pulps by Size-exclusion Chromatography and Kraft Lignin Samples by Capillary Zone Electrophoresis, Stockholm 10. Sun R., Tomkinson J. 2001: Fractional separation and physico-chemical analysis of lignins from the black liquor of oil palm trunk fibre pulping, Separation and Purification Technology 24, 529-539 11. Mohamad Ibrahim M.N., Chuah S.B. 2004: Characterization of lignin precipitated from the soda black liquor of oil palm empty fruit bunch fibres by various mineral acids, AJSTD Vol. 21, 57-67

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Streszczenie: Właściwości chemiczne, gęstość i zasadowość ługów czarnych otrzymanych podczas roztwarzania drewna natywnego i wybranych lini topoli szybkorosnących metodą siarczanową. W niniejszej pracy zostały opisanme podstawowe właściwości ługów czarnych pozyskanych metodą siarczanowa z lini topoli szybkorosnących oraz drewna natywnego (buk, brzoza, sosna, topola). W artykule zostały opisnae właściwości fiziczne ługów czarnych takie jak: gęstość, zawartość suchej masy, zawartość popiołu oraz chemiczne – zasadowść. Przeprowadzone bdania wykazują duża zależność pomiędzy badanymi właściwościami a parametrami obróbki drewna podczas roztwarzania.

Acknowledgments

This work was supported by the grant from the National Centre for Research and Development (PBS1/A8/16/2013).

Corresponding author:

Michał Drożdżek ul. Nowoursynowska 161 02-787 Warsaw, Poland e-mail: [email protected]

334 Annals of Warsaw University of Life Sciences - SGGW Forestry and Wood Technology № 96, 2016: 335-339 (Ann. WULS - SGGW, For. and Wood Technol. 96, 2016)

Effect of within-stem position and site on wood properties of Douglas-fir from the Czech Republic

ALEŠ ZEIDLER, VLASTIMIL BORŮVKA Department of Wood Processing, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Prague, Czech Republic

Abstract: Effect of within-stem position and site on wood properties of Douglas-fir from the Czech Republic This paper deals with some of physical and mechanical properties of Douglas-fir wood and factors influencing those properties. Testing trees coming from different regions in the Czech Republic were tested for wood density, shrinkage, compression strength and bending strength. Impact of vertical and horizontal position within- stem on the tested properties was also evaluated. According to the results the Douglas-fir wood from the Czech Republic is comparable to that one from native areas. It is acceptable substitute for the most of commercial native softwood from the view of tested properties. Horizontal position is one of the most important factors influencing variability of the properties. Vertical variability is not following any obvious pattern. Locality is playing role in variability only in the case of physical properties.

Keywords: Douglas-fir, wood properties, variability

INTRODUCTION Douglas-fir (Pseudotsuga menziesii /Mirb./ Franco) represents an introduced tree species with the highest production potential in the temperate vegetation zone worldwide. It represents very often planted species especially in France, Germany, Italy and United Kingdom (Podrázský et al. 2016). Its area is represented by some 5,800 ha only in the Czech Republic, with slight increase about 100 ha per year. Douglas-fir is a tree species with high potential growth and timber quality comparable to other coniferous trees even in this country. Besides the extraordinary production, this species can be considered as site improving and forest stand stabilizing species, comparing to native softwoods (Kubeček et al. 2014). As it is regarded as one of the substitute of Norway spruce in the Czech Republic and its share is rapidly growing in forest stand the issue of wood quality has become point of interest for the Czech foresters. The quality of Douglas-fir wood was studied in Germany by Hapla (1999) but very few studies on wood quality were performed in the Czech Republic (Remeš and Zeidler 2014). The aim of our research was to evaluate important physical and mechanical wood properties of Douglas-fir growing in the Czech Republic territory. We have focus on comparison with native areas and possible substitution of native softwoods. The factors influencing variability of properties, namely vertical and horizontal position in a stem and site were also evaluated.

MATERIALS The testing material presenting in this paper is coming from two different regions in the Czech Republic, both with different climate and soil conditions. Sections (1m long) from different vertical positions were cut from each sample trees, representing basal part, 20%, 40% and 60% of the tree height. Subsequently the sections were cut into boards. The central board was used from the section in order to be able to evaluate horizontal variability in a stem. Finally the central boards were cut into into lathes with cross-sections of 20 × 20 mm which were an input material for production of testing samples for individual tests.

335 From physical properties we tested wood density ρ12 (ČSN 49 0108) and shrinkage (ČSN 49 0128) in radial αR and tangential αT directions and volumetric shrinkage αV. m ρ = 12 [kg ⋅ m −3 ] 12 V 12 where m12 is the weight of the test specimen at 12% wood moisture content (kg) and V12 is the volume of the test specimen at 12% wood moisture content (m3).

V − V α = max min ⋅100 V V V min where αv is the maximum volumetric swelling in %, Vmax is the volume of the specimen at a -3 moisture content at or above the fibre saturation point in cm , Vmin is the volume of the specimen in an absolutely dry state in cm-3.

From mechanical properties we tested compression strength σC along the fibers (ČSN 49 0110) and bending strength σB (ČSN 49 0115).

F σ = max []MPa C a ⋅ b where Fmax is the maximum load (N) and a and b are the transverse dimensions of the sample (mm).

3⋅ F ⋅l σ = max []MPa B 2 b⋅⋅ h2 where Fmax is the maximum load (N), l is the distance between the two supports (mm), h is the height of the test piece (mm), and b is the width of the test piece (mm).

All the tests were performed in accordance with the Czech national standards. The results for mechanical properties and also wood density were set for 12% moisture content.

RESULTS The obtained results of the tested physical and mechanical properties of Douglas-fir wood (irrespective site and within-stem position), including descriptive statistics, are presented in the Table 1. The value of the density is slightly higher compared to that one from native areas (Alden 1997). The same is also valid for radial shrinkage and compression strength. Tangential and volumetric shrinkage are slightly lower in contrast to native areas. Bending strength of the tested trees is similar to Douglas-fir coming from North America. As far as the Czech native commercial species are concerned, namely spruce, pine, fir and larch, the value of density is higher except for larch (Wagenführ 2007). The same is also valid for bending strength. In the case of compression strength the value is similar to larch and pine, in any case it is higher compared to spruce.

Table 1. Physical and mechanical properties of Douglas-fir – descriptive statistics Standard Coefficient N Mean deviation of variation (%) Density (kg.m-3) 1,490 558 71 13.0 Shrinkage radial (%) 1,485 5.1 1.1 20.7 Shrinkage tangential (%) 1,485 6.6 1.3 19.6 Shrinkage volumetric (%) 1,485 11.6 2.0 16.9

336 Compression strength (MPa) 829 54.3 10.7 19.7 Bending strength (MPa) 793 86.0 24.0 28.0

Wood density is growing in a direction from the pith to the bark (Fig. 1), the highest value of density is so obtained in the peripheral part of the stems. The same pattern was confirmed for other tested physical and mechanical properties. 1) 850

800

750 ) 3 700

650

600 Density Density (kg/m 550

500

450 1 2 3 4 5 6 7 Horizontal position Figure 1. Horizontal variability of wood density in Douglas-fir

In vertical direction from the basal part of the stem to the crown the highest value of wood density is obtained in the bottom part, the smallest value in the upper part. In contrast to radial variability of wood density there is no clear trend. No pattern in vertical variability was found for the remaining physical and mechanical properties.

2) 590 580 570

) 560 3 550 540 530

Density Density (kg/m 520 510 500 490 1 2 3 4 Vertical position Figure 2. Vertical variability of wood density in Douglas-fir

When origin is taken into account, the second site is providing wood with higher wood density and also with higher shrinkage (in all directions and volumetric). No statistically significant difference was confirmed for compression strength and bending strength from the view of site.

Conclusions 1. The wood quality, in the terms of properties we tested, is the same or even better compared to figures reported from native areas of Douglas-fir.

337 2. Douglas-fir is reasonable substitute of Czech commercial softwoods, namely fir, spruce and pine from the view of the tested properties. But it can hardly replace larch wood. 3. Position in radial direction plays the most important role in the variability of properties. The values are growing in the direction from the center of the tree to the bark. This clear pattern can be observed in the case of all properties. 4. There is no unambiguous trend in vertical variability for the tested physical and mechanical properties. 5. Site should be taken into account as a source of variability only in the case of physical properties.

Acknowledgment The authors are grateful for the finacial support provided by the National Agency for Agricultural Research project No. QJ1520299 „Applying Douglas fir in forest management of the Czech Republic”.

REFERENCES 1. Alden H. A., 1997: Softwoods of North America. Madison, WI: U.S.D.A. Forest Service. Forest Products Laboratory. 151 pp. 2. ČSN 49 0108, 1993: Wood. Determination of density (Drevo. Zisťovanie hustoty). 3. ČSN 49 0110, 1977: Wood. Determination of compression strength parallel to the grains (Drevo – Medza pevnosti v tlaku v smere vlákien). 4. ČSN 49 0115, 1979: Wood. Determination of bending strength (Drevo – Zisťovanie medze pevnosti v statickom ohybe). 5. ČSN 49 0128, 1989: Wood. Determination of shrinkage (Skúšky vlastností rastlého dreva – Metóda zisťovani zosýchavosti). 6. WAGENFÜHR R., 2007: Holzatlas. Leipzig: Fachbuchverlag; 816 pp 7. PODRÁZSKÝ V., REMEŠ J., SLOUP R., PULKRAB K., NOVOTNÁ S., 2016: Douglas-fir – partial substitution for declining conifer timber supply – review of Czech data. Wood Research, 61, nr. 4; 525 – 530 8. KUBEČEK J., ŠTEFANČÍK I., PODRÁZSKÝ V., LONGAUER R., 2014: Results of the research of Douglas-fir in the Czech Republic and Slovakia: a review. (Výsledky výzkumu douglasky tisolisté (Pseudotsuga menziesii /Mirb./ Franco) v České republice a na Slovensku – přehled), Lesnícky časopis – Forestry Journal 60, nr. 2; 120 – 129 9. HAPLA F., 1999: Verkernung und weitere verwendungsrelevante Eigenschaften von Douglasien-Schwachholz aus unterschiedlich behandelten Jungbeständen: Folgerungen für die Sortierung und die industrielle Verwendung von Douglasien- Schwachholz. Sauerländer. Frankfurt am Main; 205 pp 10. REMEŠ J., ZEIDLER A., 2014: Production potential and wood quality of Douglas fir from selected sites in the Czech Republic, Wood Research 59, nr. 3; 509 – 520

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Streszczenie: Efekt położenia w pniu i siedliska na własności daglezji pochodzącej z Czech. Praca dotyczy wybranych własności fizycznych i mechanicznych drewna daglezji i czynników wpływających na nie. Drewno pochodząc z różnych rjonów Czech poddane zostało badaniu gęstości, skurczu, wytrzymałości na ściskanie oraz zginanie. Badano także wpływ położenia próbki w pniu. Największy wpływ na parametry zanotowano w zależności od położenia poprzecznego, siedliska zdają się oddziaływać tylko na własności fizyczne.

Corresponding author:

Aleš Zeidler, Kamýcká 129, 165021, Prague, Czech Republic email: [email protected] phone: +420 224 383 742

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