中文摘要：

采用动态热机械分析仪（DMA Q800）,在一系列恒定温湿度场（温度：25-90℃,湿度：0-93%）中测定不同含水率（0-19.39%）人工林杉木木材试样的贮存模量和损耗因子在550 min湿热耦合作用过程中的经时变化,研究湿热耦合作用对木材动态黏弹性的影响。结果表明：湿热耦合作用可以降低木材半纤维素和木质素的玻璃化转变温度。对于全干材试样,没有出现木材软化现象;对于含水率为5.88%-13.36%的木材试样,可在40-60℃温度域内观察到半纤维素的湿热软化现象;对于含水率为9.08%-19.39%的木材试样,当温度高于50℃时可观察到木质素的湿热软化现象。研究表明,升高温度或增加木材含水率均能缩短引起半纤维素和木质素发生软化的热作用时间。

英文摘要：

The hydrothermal effects of time and temperature on dynamic viscoelastic properties of Chinese fir （Cunninghamia lanceolata） were investigated using dynamic mechanical analysis （DMA Q800） in this study. The tests were applied to specimens at a series of constant temperature and humidity fields （25 - 90 ℃ , 0 -93% ） for 550 min. Changes in storage modulus and loss tangent with heating time were examined. The results indicated that the impacts of hydrothermal processes mainly resulted in the decreasing of glass transition temperature of hemieellulose and lignin. For absolutely dried wood, there was no softening occurred in this study. At the temperature range of 40℃ to 60℃ , a relaxation phenomenon was observed for wood with 5.88%- 13.36% MC, which could be attributed to the glass transition of hemicellulose. At the temperatures above 50 ℃, an increasing trend of loss factor with heating time due to the hydrothermal softening of lignin was observed for wood with 9.08%- 19.39% MC. It is suggested that the hemieeUulose and lignin softening occur at higher temperatures or higher moisture content with shorter heating times.