文献类型：期刊文献

英文题名：Moisture-dependent orthotropic viscoelastic properties of Chinese fir wood during quenching in the temperature range of 20 to-120 degrees C

作者：Li, Zhu[1] Jiang, Jiali[1] Lyu, Jianxiong[1]

第一作者：李珠

通信作者：Jiang, JL[1]|[a0005c4a974b7fbd344a8]蒋佳荔;

机构：[1]Chinese Acad Forestry, Hunan Collaborat Innovat Ctr Effect Utilizing Woo, Res Inst Wood Ind, Beijing 100091, Peoples R China

年份：2020

卷号：74

期号：1

起止页码：10-19

外文期刊名：HOLZFORSCHUNG

收录：;Scopus(收录号：2-s2.0-85071148821);WOS:【SCI-EXPANDED(收录号:WOS:000502772200002)】；

基金：This work was financially supported by the National Key Research and Development Program of China (2017YFD0600202) and the National Natural Science Foundation of China (no. 31570548).

语种：英文

外文关键词：bound water; Chinese fir wood; free water; moisture-dependent; orthotropic viscoelasticity; quenching

摘要：An understanding of wood's moisture-dependent viscoelastic properties under various temperature conditions is important for assessing its utilization and product quality. In this study, we investigated the influence of moisture content (MC) on the orthotropic viscoelasticity of Chinese fir wood (Cunninghamia lanceolata [Lamb.] Hook.) during quenching ranging from 20 to -120 degrees C. The storage modulus (E') and loss factor (tan delta) of the longitudinal (L), radial (R) and tangential (T) specimens were determined for nine MC levels ranging from 0.6 to 60.0%. The results showed that E' generally decreased with increasing amount of bound water in all orthotropic directions, regardless of the temperature. In contrast, a sharp increase in E' was observed at temperatures below 0 degrees C when free water was present, due to the formation of ice within the cell lumens. The gamma-relaxation and beta-relaxation were observed in the temperature spectrum. A comparison demonstrates that the beta-relaxation showed evident grain orientation. When only bound water was present in the wood cell wall, one clear gamma-relaxation was found for all orthotropic directions. In contrast, only the high-temperature side of the gamma-relaxation was observed in the three anatomic directions in specimens with free water, which might be related to the amorphous wood cell wall coupling with the frozen free water during the quenching process. In addition, the differences in peak temperatures of the gamma-relaxation among the three main directions diminished with increasing bound water.