| Project/Area Number |
04452290
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
林産学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
NORIMOTO Misato Kyoto Univ., Wood Res.Inst., Professor, 木質科学研究所, 教授 (20027163)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAI Shuichi Kyoto Univ., Wood Res.Inst., Assoc.Professor, 木質科学研究所, 助教授 (00135609)
MOROOKA Toshiro Kyoto Univ., Wood Res.Inst., Assoc.Professor, 木質科学研究所, 助教授 (00192378)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥4,700,000 (Direct Cost: ¥4,700,000)
Fiscal Year 1993: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1992: ¥3,500,000 (Direct Cost: ¥3,500,000)
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| Keywords | Steam Treatment / Transverse Compressive Deformation / Stress-strain Diagram / Creep / Stress Relaxation / Permanent Fixation of Deformation / 降伏点 / ヘミセルロース / 圧縮変形 / ドライングセット / 応力ーひずみ図 |
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| Research Abstract |
Compressive creep and stress relaxation measurements as well as stress-strain measurements of wood in the radial direction during steaming at various temperatures were carried out in the stainless steel autoclave which has a press within. In the stress-strain measurements, there was an excellent linear relationship between logarithm of the yield stress and temperature. Any changes in the stress-strain diagrams did not observed with elapsed time within 1300 sec below 140ﾟC, but the yield stress decreased gradually with time above 160ﾟC.In the creep measurements above 180ﾟC, the creep strain increased linearly and became very large compared to the instantaneous strain. In the stress relaxation measurements, the stress decreased considerably with time above 110ﾟC and relaxd completely immediately at 200ﾟC.After the measurements, specimens recovered more than 80% of initial thickness regardless of elapsed time at 65ﾟC, but the strain recovery decreased above 140ﾟC and almost no recovery of strain was observed after 1000 sec at 180ﾟC.In the treatment by steaming below 200ﾟC, hemicelluloses were decomposed by hydrolysis, while lignin and cellulose remained almost unchanged. From these results, it seems reasonable to suppose that the fixation of the compressed wood structure by steaming is results of looseness and softening of the lignin-hemicellulose matrix in which the crystalline cellulose microfibrils are embedded. Within the loosened and softened matrix, microfibrils can move and the stresses stored in the deformed microfibrils and matrix are released. As an application of the results obtained, we developed a new process to permanently fix the compressive deformation of wood by using moisture in wood in a closed system.
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