THESIS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Interactions between Wood Polymers in Wood Cell Walls and Cellulose/Hemicellulose Biocomposites JASNA STEVANIC SRNDOVIC The work has been carried out at INNVENTIA AB Biopolymer Technology Department of Chemical and Biological Engineering CHALMERS UNIVERSITY OF TECHNOLOGY Göteborg, Sweden 2011 Interactions between Wood Polymers in Wood Cell Walls and Cellulose/Hemicellulose Biocomposites JASNA STEVANIC SRNDOVIC ISBN 978-91-7385-517-4 © JASNA STEVANIC SRNDOVIC, 2011 Doktorsavhandlingar vid Chalmers Tekniska Högskola Ny serie nr 3198 ISSN 0346-718X Biopolymer Technology Department of Chemical and Biological Engineering Chalmers University of Technology SE-412 96 Göteborg Sweden Telephone + 46 (0) 31-772 1000 INNVENTIA AB Fibre and Material Science Business area Biorefining SE-114 86 Stockholm Sweden Telephone + 46 (0) 8-676 7000 Cover: Ultrastructure of the primary cell wall of a softwood tracheid. Chalmers Reproservice Göteborg, Sweden 2011 ii To my beautiful children, Aleksandra and Filip iii iv Interactions between Wood Polymers in Wood Cell Walls and Cellulose/Hemicellulose Biocomposites JASNA STEVANIC SRNDOVIC Department of Chemical and Biological Engineering Chalmers University of Technology Göteborg, Sweden INNVENTIA AB Fibre and Material Science Business area Biorefining Stockholm, Sweden ABSTRACT A wood fibre is a complex multi component biocomposite that is hierarchically organised. The arrangement of a wood fibre on the ultrastructural level is highly controlled by the interactions between the main structural polymers, i.e. cellulose, various hemicelluloses and lignin, as well as in some parts also pectin and protein. This further determines the mechanical and physical properties of the wood material, and consequently its targeted applications. Despite considerable research in this field during a number of years, the current knowledge on the interactions between the wood polymers is still incomplete and needs improvement. Also, mimicking of natural structures is an inspiration when preparing new materials from renewable resources, hence a comprehensive understanding of the polymer interactions is required. The first part of this study was to improve the understanding on the molecular interactions within the primary cell wall of spruce wood fibres, and its importance for the energy demand for the refining process during the thermomechanical pulp (TMP) manufacturing. Dynamic FTIR (Fourier transform infrared) spectroscopy in combination with dynamic 2D (two-dimensional) FTIR spectroscopy was used to examine how the lignin, protein, pectin, xyloglucan and cellulose interact in an enriched primary cell wall material. Measurements indicated that strong interactions exist between lignin, protein and pectin, as well as between cellulose, xyloglucan and pectin in this particular layer. Further, by applying a low degree of sulphonation pre-treatment to spruce wood chips, it was shown that the desired ultrastructural changes in the sulphonated primary cell wall material were reached. This selective reaction caused a weakening of the interactions between lignin;pectin, lignin;protein and pectin;protein, v as well as an increased softening and swelling of the material, which were the reasons for the noted energy savings when refining such low sulphonated spruce wood chips. The second part of this study was to improve the current knowledge on the molecular interaction within the secondary cell wall of a spruce wood fibre, as well as its ultrastructure by studying the orientation of the cellulose, glucomannan, xylan and lignin. Imaging FTIR microscopy was a technique used for studying, which indicated a parallel orientation of polysaccharides with respect to each other and the fibre axis and a partial parallel orientation of lignin. It was suggested that the interactions between the cellulose and glucomannan and the xylan and lignin are dominant but also that interactions between the two hemicelluloses, i.e. glucomannan and xylan, exist. The third part of this study was to prepare biomimetic biocomposite films, based on cellulose reinforced hemicelluloses. The interactions between these polysaccharides were studied through the prior examined mechanical properties of the biocomposite films using dynamic mechanical analysis (DMA). Here, the understanding of the ultrastructural organisation of the primary and secondary cell walls has been taken as a basis. Intramolecular hydrogen bonding might be created between the cellulose molecules and the unsubstituted areas of the backbone of the hemicellulose molecules, where the lower degree of substitution of xylan results in a more frequent occurrence of intermolecular hydrogen bonding. This study contributes to an increased understanding between interactions of wood polymers in the primary and secondary cell walls of a softwood tracheid and may serve as a guide for the new generation of biomimetic biocomposites. Keywords: polymer interactions, viscoelasticity, orientation, primary cell wall, secondary cell wall, nanocomposite films, dynamic FTIR spectroscopy, dynamic 2D FTIR spectroscopy, imaging FTIR microscopy, DMA, Norway spruce, wood fibre, cellulose, xyloglucan, xylan, glucomannan, pectin, protein, lignin. vi List of publications This thesis is based on the work contained in the following papers: Paper I Characterizing wood polymers in the primary cell wall of Norway spruce (Picea abies (L.) Karst.) using dynamic FT-IR spectroscopy Jasna S. Stevanic* and Lennart Salmén 2008 Cellulose 15(2):285-295 Paper II The primary cell wall studied by dynamic 2D FT-IR: Interaction among components in Norway spruce (Picea abies) Jasna S. Stevanic* and Lennart Salmén 2006 Cellulose Chemistry and Technology 40(9-10), 761-767 Paper III Interactions among components in the primary cell wall of Norway spruce; How they are affected by different chemimechanical treatments? Jasna S. Stevanic* and Lennart Salmén 2008 Journal of Pulp and Paper Science 34(2):107-112 Paper IV Orientation of the wood polymers in the cell wall of spruce wood fibres Jasna S. Stevanic* and Lennart Salmén 2009 Holzforschung 63:497-503 Paper V Bacterial nanocellulose reinforced arabinoxylan films Jasna S. Stevanic, Catherine Joly, Kirsi S. Mikkonen, Kari Pirkkalainen, Ritva Serimaa, Caroline Rémond, Guillermo Toriz, Paul Gatenholm, Maija Tenkanen, Lennart Salmén* 2011 Journal of Applied Polymer Science xxx:xxx-xxx, in press On-line publication: DOI 10.1002/app.34217 Paper VI Composite films from spruce galactoglucomannans with microfibrillated spruce wood cellulose Kirsi S. Mikkonen*, Jasna S. Stevanic, Catherine Joly, Patrice Dole, Kari Pirkkalainen, Ritva Serimaa, Lennart Salmén, Maija Tenkanen 2011 Cellulose xx:xxx-xxx, in press On-line publication: DOI 10.1007/s10570-011-9524-0 vii Contribution report Paper I Main author. Took an active part in planning the experiments and performed most of the experimental work. Paper II Main author. Took an active part in planning the experiments and performed most of the experimental work. Paper III Main author. Took an active part in planning the experiments and performed most of the experimental work. Paper IV Main author. Took an active part in planning the experiments and performed most of the experimental work. Paper V Co author. Took an active part in planning the experiments and performed most of the experimental work regarding the preparation of films, tensile and mechanical testing using DMA. Paper VI Co author. Took an active part in planning the experiments and performed most of the experimental work regarding the preparation of films, tensile and mechanical testing using DMA. viii Other relevant publications Analysis of thermally treated wood samples using dynamic FT-IR-spectroscopy Lennart Salmén*, Hans Possler, Jasna S. Stevanic and Stefanie E. Stanzl-Tschegg 2008 Holzforschung 62:676–678 Localisation and characterisation of incipient brown-rot decay within spruce wood cell walls using FT-IR imaging microscopy Karin Fackler*, Jasna S. Stevanic, Thomas Ters, Barbara Hinterstoisser, Manfred Schwanninger, Lennart Salmén 2010 Enzyme and Microbial Technology 47:257-267 FT-IR imaging microscopy to localise and characterise simultaneous and selective white-rot decay within spruce wood cells Karin Fackler*, Jasna S. Stevanic, Thomas Ters, Barbara Hinterstoisser, Manfred Schwanninger, Lennart Salmén 2011 Holzforschung 65:xxx-xxx, in press On-line publication: DOI 10.1515/HF.2011.048 Cell wall polymers orientation in fibres from branches of hardwood and softwood – a polarized FTIR study Jasna Simonovi, Jasna S. Stevanic, Daniela Djikanovi, Lennart Salmén*, Ksenija Radoti* Submitted to Macromolecular bioscience Structural organisation of the wood polymers in the wood fibre structure Lennart Salmén*, Anne-Mari Olsson, Jasna S. Stevanic, Jasna Simonovi, Ksenija Radoti 2011 Proceedings of the 16th ISWFPC, Tianjin pp.xxx-xxx, in press ix Abbreviations AGX arabinoglucuronoxylan AX arabinoxylan BC bacterial cellulose CTMP chemithermomechanical pulp DMA dynamical mechanical analysis DP degree of polymerisation 2D FTIR two dimensional Fourier transform infrared σ B stress at break E Young’s modulus E' storage modulus ε B strain at break FTIR Fourier transform infrared GGM galactoglucomannan gly glycerol H holocellulose fibre with exposed S2 cell wall LCC lignin-carbohydrate complex MFC microfibrillated cellulose NMR nuclear magnetic resonance P primary cell wall rAX rye arabinoxylan rDAX rye debranched arabinoxylan RH relative humidity S secondary