| Co-Investigator(Kenkyū-buntansha) |
MINAT Kazuya Kyoto University, Faculty of Agriculture, Instructor, 農学部, 助手 (10026601)
MOROOKA Toshiro Kyoto University, Wood Research Institute, Associate Professor, 木質科学研究所, 助教授 (00192378)
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| Research Abstract |
Chemical treatments are one of effective approach to control woood properties. To reduce some defects, enhance its prpperties, and create new performance or functions, it is imprtant to have a clear understanding of the relationship between the structural modifications of the cell wall material and changes in properties. Chemically treated woods were cassified according to a double criterion, modification of the cell lumens and modification of the cell wall materials. For fourteen different types of chemically treated wood, adsorption tests, dimensional stabilization tests, static bending tests, mechanosorptive creep tests, dynamic viscoelastic measurements, and dielectric measurements were performed. The filling lumens partially or totally with hydrophobic chemicals was effective to to improve rigidity and strength. Modification of the cell wall at the molecular level was required to affect either moisture expansion or mechaosorptive creep. In the case of treatments that induced cross
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linking, a good correlation could be expected to reduce both moisture expansion and mechanosorptive creep. The hydrophilic bulking of the cell wall alone induced low moistrue expansion and high mechanosorptive creep. In all types of the treatments except for vapor phase formalization, a decrease of specific Young's modulus would be expected, because bulking of the cell wall either reduced the molecular cohesion, or improved it, but not enough to compensate for the increase in density. The dependency of internal friction on the type of treatment was close to that of mechanosorptive creep because both measurements were related to viscous movement of molecules. Dielectric measurements gave information on the formation of chemical bonding or interaction between hydroxyl group in the cell wal molecules and chemicals introduced into the cell wall. Numerical analysis by using the models proposed clarified contitatively the effects of structure on such properties as specific Young's modulus, internal friction and dielectric constant. Less
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