Thermal behaviors and transitions of wood detected by temperature-modulated differential scanning calorimetry

被引:0
作者
Tsunehisa Miki
Hiroyuki Sugimoto
Keisuke Kojiro
Yuzo Furuta
Kozo Kanayama
机构
[1] National Institute of Advanced Industrial Science and Technology,Graduate School of Life and Environmental Science
[2] Misawa Homes Institute of Research and Development Co.,undefined
[3] Ltd. (MHIRD),undefined
[4] Kyoto Prefectural University,undefined
来源
Journal of Wood Science | 2012年 / 58卷
关键词
Temperature-modulated differential scanning calorimetry; Glass transition; Enthalpy relaxation; Activation energy;
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中图分类号
学科分类号
摘要
The thermal properties and transitions of solid and ground wood samples conditioned at different humidity conditions were investigated by temperature-modulated differential scanning calorimetry. A time-dependent transition was detected as an endothermic peak in the total and non-reversing heat flows and as a step change in the reversing heat flow during the first heating run of samples with moisture contents above 5 %, but it disappeared in the second heating run. These different thermal behaviors indicate that the effect of heat and moisture on the thermal properties of wood is history dependent. This step change in the reversing heat flow is considered to be a glass transition of moist wood. Other relaxation processes (e.g., enthalpy relaxation) occur simultaneously with this glass transition. The temperature ranges of the transition and the relaxation decreased drastically as the moisture content increased up to 11 %, while they remained almost constant at higher moisture contents. In addition, the transitions of the ground wood occurred at lower temperatures than those of the solid wood at similar moisture contents. Kissinger plots revealed that the apparent activation energy for the glass transition of the solid wood with a moisture content of 11 % was about 600 kJ/mol, whereas that of the ground wood was 220 kJ/mol.
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页码:300 / 308
页数:8
相关论文
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