摘要
动态力学分析技术(DMA)通过材料的结构和分子运动状态表征材料的力学性能。木质材料的力学性能本质上是分子运动状态的反映,利用DMA可以架构其结构与性能之间的关系,获得木质材料的结构、分子运动及其转变等重要信息。分别总结了DMA在实体木材和木质复合材料中的应用:围绕实体木材,综合评述了DMA在分析木材材性、软化行为、机械吸湿效应以及早期腐朽程度方面所取得的研究进展;针对木质复合材料,重点介绍了DMA在分析其阻尼性能、胶合性能、界面相容性能和耐老化性能等方面的应用。建议今后的研究重点从以下3个方面展开:1)考虑到实体木材自身组织结构的复杂性以及易受环境影响等特点,采用DMA分析仪不同的载荷类型和形变模式进行组合测试,在一定温湿度场中系统研究实体木材的材性与软化行为和机械吸湿效应的关系。2)利用DMA分析仪的单纤维拉伸模式,探索单根纤维(管胞、木纤维细胞)的黏弹行为,进一步明晰木质材料微观黏弹性能的响应机制。3)联用振动光谱(红外光谱或拉曼光谱),实现同步实时观察木质材料形变过程中组成分子的化学键或官能团的变化及响应,进而从分子水平揭示木质材料的形变规律。
Dynamic mechanical analysis(DMA)is a useful thermo-mechanical analysis technique for studying the elastic and viscoelastic behavior of polymers under a static or dynamic force as a function of time or temperature.The DMA provides the opportunity to examine composite properties and the response of individual wood components in situ,and furthers the understanding of the contributions made by individual wood polymers,as well as their interaction.The DMA can be simply described as an oscillating force to a sample and analyzing the material s response to that force,which contains information of sample stiffness(storage modulus E′)and damping property(loss modulus E″and damping factor tanδ).A wide range of fixtures or jigs are available,which allows that samples can be tested in various shapes and forms.These include tension,flexure,compression and shear.The DMA is also possible to observe the response of wood to moisture conditions because it can adjust temperature and humidity of ambient condition.This paper reviewed the applications of DMA on solid wood and wood-based materials,respectively.For solid wood,the emphases were on the wood properties,softening behavior,mechano-sorptive effect and initial decay process.For wood-based materials,the emphases were on damping property,adhesion strength,interfacial interaction and ageing-resistant performance.In the future,the following three research topics were suggested:1)To use DMA instruments combined with loading directions and deformation modes at a certain temperature and humidity field to clarify wood properties,softening behavior and mechano sorptive effect by considering anatomic characteristics of wood and moisture dependence behavior.2)To investigate the viscoelastic behavior of single wood fiber,which is essential to illuminate the wood mechanical behavior.3)To investigate the deformation of molecular bonds or functional groups under loading using the Fourier transform infrared or Raman spectroscopy to reveal the evolution of wooden material s deformation at molecular level.
作者
吕建雄
彭辉
曹金珍
蒋佳荔
赵荣军
高玉磊
LYU Jianxiong;PENG Hui;CAO Jinzhen;JIANG Jiali;ZHAO Rongjun;GAO Yulei(Key Laboratory of Wood Science and Technology of State Forestry Administration,Chinese Academy of Forestry,Beijing 100091,China;Hunan Collaborative Innovation Center for Effective Utilizing of Wood&Bamboo Resources,Central South University of Forestry and Technology,Changsha 410004,China;College of Materials Science and Technology,Beijing Forestry University,Beijing 100083,China)
出处
《林业工程学报》
北大核心
2018年第5期1-11,共11页
Journal of Forestry Engineering
基金
国家重点研发计划项目(2017YFD0600202)
木竹资源高效利用湖南省高校2011协同创新中心项目。
