文献类型：期刊文献

英文题名：Effects of the ice formation and its content on viscoelastic characteristics of wood exposure to low temperatures ranging from -125°C to 25°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]

机构：[1]Chinese Acad Forestry, Res Inst Wood Ind, Beijing 100091, Peoples R China

年份：2024

外文期刊名：WOOD MATERIAL SCIENCE & ENGINEERING

收录：;EI(收录号：20242116150511);Scopus(收录号：2-s2.0-85193984450);WOS:【SCI-EXPANDED(收录号:WOS:001229873300001)】；

基金：This work was financially supported by the Fundamental Research Funds of the Chinese Academy of Forestry (CAFYBB2023MA019)

语种：英文

外文关键词：Wood; orthotropic viscoelasticity; ice formation; free water content; low temperatures

摘要：The influence of ice formation and its content on the viscoelastic characteristics of wood were investigated in the temperature range between -125 degrees C and 25 degrees C. The stiffness and damping properties of the longitudinal (L), radial (R) and tangential (T) specimens were determined for different moisture content (MC) levels at or above the fiber saturation point (FSP) ranging from 25% to 300%. Results showed that the E ' value was correlated negatively with temperature for all specimens. Accompanied by the frozen free water inside the wood, the order of magnitude in E ' for specimens in the different anatomical directions trend toward an accord. The increment in E ' (Delta E ') of specimens was correlated positively with the ice content, and Delta E ' in the L direction was lower than those in the R and T directions at each MC level. The gamma-relaxation ranged from -112.9 degrees C to -94.8 degrees C was observed for all orthotropic directions at 10 Hz, which was assigned to the reorientation of methylol groups and adsorbed water molecules in the wood cell walls. At each MC level, a lower peak temperature of gamma-relaxation was observed in the L specimens compared to the transverse specimens. Notably, the gamma-relaxation peak temperature in the E '' and tan delta spectrum showed obvious frequency-dependence, and the apparent activation energy (Delta H) of gamma-relaxation over the measured MC range was about 38.08 similar to 69.57 KJ/mol. The Delta H value was close for specimens in orthotropic grain orientations, indicating that this gamma-relaxation phenomenon was not affected by its orthotropic structure and also related closely with the formation of ice in the wood cell lumens.