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Author (up) Alméras, T.; Gronvold, A.; van der Lee, A.; Clair, B.; Montero, C.
Title Contribution of cellulose to the moisture-dependent elastic behaviour of wood Type Journal Article
Year 2017 Publication Composites Science and Technology Abbreviated Journal Composites Science and Technology
Volume 138 Issue Pages 151-160
Keywords Cellulose; Crystal strain; Micromechanics; Wood; X-ray diffraction
Abstract Wood has a hierarchical structure involving several levels of organisation. The stiffness of wood relies on its capacity to transfer mechanical stress to its stiffest element at the lowest scale, namely crystalline cellulose. This study aims at quantifying to what extend crystalline cellulose contributes to wood stiffness depending on its moisture content. The crystal strains of cellulose were measured using X-ray diffraction on wet and dry specimens of spruce, based on a previously published methodology. The comparison between crystal strain and macroscopic strain shows that, during elastic loading, cellulose strain is lower than macroscopic strain. The means ratio of crystal/macroscopic strain amounts 0.85 for dry specimens and 0.64 for wet specimens. This strain ratio cannot be explained just by the projection effect due to the difference in orientation between cellulose microfibrils and cell wall, but results from deformation mechanisms in series with cellulose. Analysis shows that this series contribution represents a non-negligible contribution to wood compliance and is strongly moisture-dependent. This contribution amounts 9% for dry specimens and 33% for wet specimens, corresponding to a 4-fold increase in compliance for the series contribution. The origin of these strains is ascribed to mechanisms involving bending or shear strain at different scales, due to the fact that reinforcing element are neither perfectly straight nor infinitely long. © 2016
Address CNRS, UMR Ecologie des Forêts de Guyane (EcoFoG), AgroParisTech, Cirad, INRA, Université des Antilles, Université de Guyane, Kourou, France
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Notes Export Date: 26 December 2016 Approved no
Call Number EcoFoG @ webmaster @ Serial 701
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