文献类型：期刊文献

英文题名：Influence of Frequency on Wood Viscoelasticity under Two Types of Heating Conditions

作者：Jiang, Jiali[1] Lu, Jianxiong[1] Zhao, Youke[1] Wu, Yuzhang[1]

第一作者：蒋佳荔

通信作者：Lu, JX[1]

机构：[1]Chinese Acad Forestry, Res Inst Wood Ind, Key Lab Wood Sci & Technol, State Forestry Adm, Beijing 100091, Peoples R China

年份：2010

卷号：28

期号：6

起止页码：823-829

外文期刊名：DRYING TECHNOLOGY

收录：;EI(收录号：20102312990758);Scopus(收录号：2-s2.0-77953101822);WOS:【SCI-EXPANDED(收录号:WOS:000278139300010)】；

基金：This work was funded by the National Natural Science Foundation of China (No. 30825034).

语种：英文

外文关键词：Chinese fir; Dynamic viscoelastic properties; Iso-heated wood; Rapid-heated wood; Scanning frequency

摘要：During lumber drying, heating speed affects the dried lumber quality and properties such as strength, elasticity, and viscoelasticity. The dynamic viscoelastic properties of Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) were investigated under two types of heating conditions: (1) specimens were conditioned at different constant temperatures ranging from 25 to 180 degrees C for a long time, which is referred to as iso-heated wood, and (2) specimens were heated rapidly from 25 to 40-180 degrees C, which is referred to as rapid-heated wood. Specimen dynamic viscoelastic behavior was measured in the frequency range between 0.1 and 100Hz. Changes in storage modulus and loss factor with frequency were examined at each temperature level. The results indicated that the storage modulus decreased as temperature increased and decreased as frequencies dropped from 100 to 0.1Hz. The minimum value of loss factor slightly shifted toward higher frequencies at higher temperatures. In general, rapid-heated wood exhibited lower stiffness and higher damping than iso-heated wood. This indicated that the unstable state was caused by rapid heating. The difference in stiffness between rapid-heated wood and iso-heated wood increased progressively with higher temperatures. The damping differences had a maximum value at 1Hz. The minimum loss frequency that corresponds to the minimum loss factor for rapid-heated wood was higher than that for iso-heated wood. It could be deduced that the unstable structures were formed in the wood cell walls because of rapid heating and consequently increased mobility of molecular chains.