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The Wood Fibre Structure How to Be Utilised?

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The Wood Fibre Structure How to Be Utilised? The wood fibre structure how to be utilised? Lennart Salmén Innventia The wood fibre as a material resource . Increasing demand for utilising wood fibres – Cellulose; . replacing cotton . derivatives – Hemicelluloses . barrier films – Lignin . carbon fibres The wood fibre structure . Cellulose aggregation . Polymer orientation . Matrix polymer interactions . Lignin/cellulose cooperation Cellulose . Using ability – accessibility . Obstacles – thermodynamic preference for aggregation Ultra-structure across cell wall 500nm lumen side middle lamella side Three dimensional cellulose structure lignin cellulose/hemicellulose undulating structure Aggregate size distribution 10 dried wood 8 never 6 dried wood 4 2 Frequency 0 0 5 10 15 20 25 30 Cellulose fibril aggregate size (nm) Aggregate size - drying 18 never dried wood 16 14 dried wood 12 10 ML-side interior lumen side S 2 wall Cellulose aggregates during cooking Aggregation due to heat treatment 12 10 Heat treated wood 8 6 Frequency 4 Native wood 2 0 0 5 10 15 20 25 30 35 40 Cellulose fibril aggregate size, nm Aggregering av cellulosa increased mobility Effects of hemicelluloses 22 extraction of 20 glucomannan 18 holocellulose 16 extraction of xylan Cellulose aggregate size, nm size, aggregate Cellulose 14 0 10 20 30 40 Hemicellulose content, % Structure around cellulose aggregates glucomannan cellulose lignin xylan cellulose aggregates Manipulation cellulose aggregate size Aggregate Rewet thickness zero-span Sample (nm) (Nm/g) Never Dried pulp 26.8 +/- 0.8 137 +/- 6 De-aggregated pulp (NaOH) 24.4 +/- 0.5 118 +/- 5 Re-aggregated pulp (dried) 35.0 +/- 2.5 Tear - tensile – aggregate size 30 25 OH treated 20 /g 2 , 15 OH treated + dried 10 5 Tear index, mNm index, Tear 0 0 20 40 60 80 100 120 Tensile index, Nm/g Pulping challange . Restrict aggregation . Increasse cellulose specific surface area Controling aggregate size reduced specific surface increased pore volume severely reduced specific surface decreased pore volume Highly organised cellulose aggregate structure O(3) O H H O H 6 3 1 4 O O 5 2 O 4 O 2 5 1 4 3 6 O H O O H O H Cellulose 1316 C 1316 C 1425 vibration backbone 1160 Polarisation FTIR for molecular orientation - - H vibration OH bending 2 wagging vibration wagging 0 o 90 o Orientation of cellulose groups in poplar 1 0.8 1425 cm-1 0.6 0.4 cellulose relative absorbance relative 0.2 1160 cm-1 0 0 10 20 30 40 50 60 70 80 90 degree of polarisation, ° Polarisation FTIR for H molecular orientation H Glucomannan -1 H 810 cm equatorially aligned H vibration in mannose units Orientation of glucomannan groups in softwood 1 C – H 810 cm-1 -1 C – H2 1316 cm absorbance 0.5 glucomannan Relative Relative cellulose 0 0 10 20 30 40 50 60 70 80 90 degree of polarisation, ° Polarisation FTIR for molecular orientation Xylan 1460 cm-1 H CH2 symmetric bending on xylose units 1240 cm-1 C-O stretching in carboxylic group H 1734 cm-1 , 54o C=O stretching in carbonyl group Orientation of xylan groups in poplar 1 0.8 C-O 1235 cm-1 0.6 C=O 1740 cm-1 -1 CH2 1460 cm 0.4 xylan relative absorbance relative 02 cellulose 0 0 10 20 30 40 50 60 70 80 90 degree of polarisation, ° Polarisation FTIR for molecular orientation Lignin 1508 cm-1 aromatic ring vibration 1600 cm-1 aromatic ring + C - O stretch Orientation of lignin groups in softwood – S2 1 0.8 lignin, 1500 cm-1 0.6 0.4 Relative absorbance Relative 0.2 cellulose, 1160 cm-1 0 10 30 50 70 90 Polarisation angle o Absolute absorbance – polar diagram, spruce - S2 0.35 0.3 o 0.25 lignin, 1500 cm-1 90 0.2 cellulose, 1160 cm-1 0.15 Absorbance 0.1 0.05 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Absorbance 0o Radially cut cross section of spruce increased absorbance, arbitrary scale 100 m m IR -radiation Absolute absorbance – polar diagram, spruce - ML 0.12 0.1 -1 o lignin, 1500 cm 0.08 90 0.06 cellulose, 1160 cm-1 0.04 Absorbance 0.02 0 0 0.05 0.1 0.15 0.2 Absorbance 0o Three-dimensional lenticular structure of cell wall Space restrictions for lignin deposition lignin cellulose/hemicellulose undulating structure Different types of secondary wall lignins cellulose glucomannan lignin xylan lignin 1.6 LCC-bonds per hemicellulose chain Softening temperature of different wood species 80 75 70 65 at 0.1 Hz 0.1 at Softening temperature Softening 60 80 100 120 140 160 180 200 Methoxyl group content, mol% Lignin space Lignin space volume diameter 5 to 15 nm Polymer interaction - FT-IR spectroscopy Static absorbance Polarizer Detector IR-source Sample Straining Dynamic FTIR -spectra 1.6 0.004 0.002 1.2 0.000 0.8 dynamic response dynamic cellulose -0.002 xylan 0.4 glucomannan static absorbency static 0 1800 1600 1400 1200 1000 800 wave number, cm -1 Wood – cellulose, lignin deformation 0 1 - 1509 cm -1, lignin -2 90% RH -4 -1 1160 cm , cellulose -6 wavenumber shift, cm shift, wavenumber 0 5 10 15 20 25 30 stress, MPa Interactions in the primary cell-wall Cellulose Lignin Xyloglucan Pectin + – Protein Deformation of primary wall 0.002 -1 1425 cm 0.001 1510 cm -1 0 Response 0.001- 1800 1700 1600 1500 1400 1300 1200 Wavenumber, cm -1 Lignin deformation in secondary wall straining of the cellulose cellulose aggregate aggregate network lignin/ hemicellulose matrix Cellulose – molecular deformation 1160 cm-1 deformation O(3) O H H OH O O 3 1 2 O 4 O 5 6 O HO O H O H Cellulose main chain vibration, 1160 cm-1 0.8 0.7 increased stress 0.6 absorption intensity absorption 0.5 1180 1170 1160 1150 1140 1130 wavenumber, cm-1 Cellulose chain deformation 0 -1 -1 1 - 1160 cm -2 0% RH -3 -4 90% RH -5 wavenumbershift, cm -6 -7 0 10 20 30 40 stress, MPa Stretching of the hydrogen bond 3348 cm-1 deformation O(3) O H H OH O O 3 1 2 O 4 O 5 6 O HO O H O H Deformation - OH 8 -1 3348 cm 90% RH 1 - 6 4 0% RH 2 wavenumbershift, cm 0 0 10 20 30 40 stress, MPa Cellulose chain deformation 0 -1 -1 1 - 1160 cm -2 0% RH -3 -4 90% RH -5 wavenumbershift, cm -6 -7 0 10 20 30 40 stress, MPa Relation to strain 0 1 - -1 1160 cm -2 -4 0 %RH 90 %RH wavenumber shift, cm shift,wavenumber -6 0.0 0.5 1.0 1.5 2.0 2.5 3.0 strain, % Accessible regions more or less arranged parallel to the cellulose crystalls equal stress equal strain crystalline cellulose or accessible cellulose parallel arrangement serial arrangement of cellulose structures of cellulose structures Accessible regions more or less arranged parallel to the cellulose crystalls equal stress equal strain crystalline cellulose or accessible cellulose parallel arrangement serial arrangement of cellulose structures of cellulose structures Softening in RH region 60 50 spruce wood 40 30 ridgid 20 10 soft 0 longitudinal modulus, GPa modulus, longitudinal 0 10 20 30 40 50 fibril angle Cellulose – load bearing structure straining of the cellulose cellulose aggregate aggregate network lignin/ hemicellulose matrix Disintegration of cell wall . Combination of; – Chemical - – Enzymatic - – Mechanical - approaches Entering the forestry era! .
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