文献类型：期刊文献

英文题名：The orthotropic viscoelastic properties of Chinese fir wood during the temperature ramping process

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：38

期号：11

起止页码：1411-1420

外文期刊名：DRYING TECHNOLOGY

收录：;EI(收录号：20193207282106);Scopus(收录号：2-s2.0-85088909833);WOS:【SCI-EXPANDED(收录号:WOS:000477414500001)】；

基金：This research was financially sponsored 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：Chinese fir wood; orthotropic viscoelasticity; Cole-Cole diagrams; moisture content; heating; water-loss process

摘要：In this study, the orthotropic viscoelasticity of Chinese fir wood (Cunninghamia lanceolata [Lamb.] Hook) was investigated during the temperature ramping process. The storage modulus (E ') and loss modulus (E '') of longitudinal (L), radial (R), and tangential (T) specimens with six levels of moisture content (MC) ranging from 0.6 to 22.0% were determined form 20 to 280 degrees C. The change in E ' was influenced by the dual effects of temperature and MC; the loss of adsorbed water in the wood cell wall caused an increase in wood stiffness. The individual decline in E ' was affected by heating to different degrees and the heating exerted more influence on the transverse specimens and less contribution to the L specimens. Different relaxation processes of E '' were observed in specimens with different MCs in the three main directions, indicating that the mechanical relaxation of wood was affected by its MC and microstructure. The beta and gamma-relaxation processes exhibited a conjointly circular arc shape in the transverse directions, which was attributed to the superposition of the transitions of lignin and hemicellulose. A higher alpha-loss peak temperature (alpha-T-LP) and intensity of the alpha-relaxation process were observed in the L specimens than the transverse specimens. The beta-T-LP and gamma-T-LP decreased with increasing MC in all orthotropic directions, whereas the individual decline in T-LP was affected differently by MC. In the beta-relaxation process, the T-LP was more sensitive to MC changes in the L direction than in the transverse directions. In addition, the individual T-LP in the R and T directions was influenced by per unit adsorbed water to a similar degree for the beta and gamma-relaxation processes. These findings suggest that the difference in the orthotropic viscoelastic performance might cause some drying defects during the water loss process.