文献类型：期刊文献

英文题名：Dynamic viscoelastic properties of Chinese fir (Cunninghamia lanceolata) during moisture desorption processes

作者：Zhan, Tianyi[1] Jiang, Jiali[1] Peng, Hui[1] Lu, Jianxiong[1]

第一作者：Zhan, Tianyi

通信作者：Lu, JX[1]

机构：[1]Chinese Acad Forestry, State Key Lab Tree Genet & Breeding, Res Inst Wood Ind, Beijing 100091, Peoples R China

年份：2016

卷号：70

期号：6

起止页码：547-555

外文期刊名：HOLZFORSCHUNG

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000376680300008)】；

基金：This study was completed at the State Key Laboratory of Forest Genetics and Tree Breeding and financially supported by Open Fund of State Key Laboratory of Forest Genetics and Tree Breeding (No. TGB2015005), Chinese Academy of Forestry, Beijing 100091, P.R. China.

语种：英文

外文关键词：Chinese fir; DMA during moisture desorption; dynamic mechanical analysis (DMA); frequency dependent DMA; modes of RH reduction; moisture desorption; relative humidity (RH); unstable state; viscoelasticity of wood

摘要：The viscoelasticity of Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) during moisture desorption-processes were examined at 30 degrees C and two relative humidity (RH) modes: RHramp-down mode from 85 to 0% RH, and RHisohume mode at 0, 30, and 60% RH, respectively. Dynamic viscoelastic properties were determined in a multi-frequency range of 1, 2, 5, 10, and 20 Hz. In both RH modes, desorption of water resulted in increasing stiffness and decreasing damping. The reduction in moisture content caused an unstable state in the cell wall due to the formation of free volumes in cell wall and rearrangement of hydrogen bonds within the polymer networks. Higher ramping rates resulted in greater destabilization, and the unstable state was more pronounced at a lower frequency. The ratio of storage modulus at 1 and 20 Hz remained unchanged during both RH modes. The ratios of loss modulus and loss factor at 1 and 20 Hz increased during the RHramp-down and decreased during the RHisohume period. The changes of loss modulus or loss factor ratios at two frequencies were suitable for evaluation of the unstable state. The instability was aggravated with reducing RH and slightly recovered at constant RH.