SUPPORTING INFORMATION

Transcription

1 SUPPORTING INFORMATION Morphology and overall chemical characterization of willow (Salix sp.) inner bark and wood: towards controlled deconstruction of willow biomass Jinze Dou a, Leonardo Galvis a, Ulla Holopainen-Mantila b, Mehedi Reza c, Tarja Tamminen b, Tapani Vuorinen a, * a Department of Forest Products Technology, School of Chemical Technology, Aalto University, P.O. Box 16300, Aalto, Finland b VTT Technical Research Centre of Finland Ltd., P.O Box 1000, VTT, Finland c Department of Applied Physics, School of Science, Aalto University, P.O. Box 11100, Aalto, Finland * Corresponding author: Tapani Vuorinen Tel: Fax: tapani.vuorinen@aalto.fi. Number of pages: 04 Number of figures: 03 Number of tables: 02 S1

2 1 Samples Ca. 2 cm thick stems of naturally growing goat willow (Salix caprea) were collected in spring time in Espoo, Finland. The thin outer bark layer was removed by scratching with a knife after which the inner bark was separated and cut into chips of 3-4 cm in length. 2 Pulping of willow inner bark The willow inner bark chips were delignified using the kraft pulping method (Table S1). The gravimetric pulp yield was 38.0 %, kappa number 33.5 (ISO 302:2004), viscosity 1266 cm 3 /g (ISO 5351:2004) and brightness 13.5 % (ISO 2470). Table S1. Kraft pulping conditions Liquor - to - bark ratio 4.5 Sulfidity, % 40 Alkali charge, % 20 H factor 1860 Cooking temperature, o C Sheet properties of willow inner bark pulp The pulps were disintegrated in tap water and prepared for sheets in laboratory sheet former (KCL style) according to standard methods (Table S2). The sheets were dried in a drying drum at 65 C for 2 hours and then stored in a climate room at 50% RH and 23 C prior to testing. In comparison with normal hardwood and softwood kraft pulp sheets were superior in strength at a given density (Fig. S1). Table S2. Standard for willow inner bark sheet property measurement Disintergration for the innerbark pulp ISO 5263 Handsheet mold ISO 5269 Conditioning for the paper sheet ISO 187 Basis weight (grammage) ISO 536 Thickness (density) ISO 534 S2

3 Tensile strength ISO Figure S1. Tensile strength vs. density of sheets of unbleached kraft pulps of willow inner bark (this study), softwood mixture of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies), eucalyptus (Eucalyptus urograndis) and Silver birch (Betula pendula/betula pubescens). Trendlines L1 and L2 denote respectively the softwood and hardwood pulps. 1 4 Microfibril angle in willow inner bark fibres The determination of microfibril angle in a single fibre of willow inner bark was performed by using Raman spectroscopy. 2,3 Prior to the measurements, the willow inner bark fibres were treated with 1:1 glacial acetic acid/ hydrogen peroxide at 40 o C for 48 hours to remove the lignin and decrease the fluorescence. A single fibre was placed on plane at 0 o (XY stage coordinate system) and Raman spectra of thirteen different polarization angles of the laser were recorded using the alpha 300 R confocal Raman microscope (Witec GmbH, Germany) with a doubled frequency Nd:YAG laser (532 nm, 40 mw) focused onto the sample using a 40X (Nikon, NA = 0.40) air objective. The spectra were acquired using a CCD (DU970N-BV) behind a grating (600 grooves/mm) spectrograph (Acton, Princeton Instruments, Inc., Trenton, NJ). An integration time of 0.3 s was used for collecting each S3

4 spectrum. The baseline correction was performed with WiTec project 2.10 (Witec GmbH, Germany) using a fifth order polynomial. A plot of the intensity ratio of Raman bands 1122/1095 vs polarization angle of the laser shown on Fig S2 with minimum value at ~-2 o is the result of cellulose microfibrils oriented almost parallel to the fibre. Figure S2. Raman spectra of a single willow inner bark fiber placed on plane at 0 o for two different polarization angles 0 o (red color) and 90 o (blue color). S4

5 Figure S3. Plot of intensity ratio of Raman bands 1122/1095 vs polarization angle of the laser on a single willow inner fibre placed on plane at 0 o. References (1) Antonsson, S.; Mäkelä, P.; Fellers, C.; Lindström, M. E. Comparison of the physical properties of hardwood and softwood pulps. Nord. Pulp. Pap. Res. J. 2009, 24 (4). (2) Barnett, J. R.; Bonham, V. A. Cellulose microfibril angle in the cell wall of wood fibres. Biol. Rev. 2004, 79 (2), (3) Gierlinger, N.; Luss, S.; König, C.; Konnerth, J.; Eder, M.; Fratzl, P. Cellulose microfibril orientation of Picea abies and its variability at the micron-level determined by Raman imaging. J. Exp. Bot. 2010, 61 (2), S5