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首页> 外文期刊>Journal of Polymers and the Environment >Viscoelasticity of Air-Dried or Thermo-Treated Woods
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Viscoelasticity of Air-Dried or Thermo-Treated Woods

机译：风干或热处理木材的粘弹性

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Viscoelasticity of air-dried or thermo-treated Cedrus deodara and Alnus cordata has been evaluated by means of Dynamic Mechanical Analysis (DMA) in the bending mode at 30 degrees C. E-1, E-2 and tan delta have been investigated by frequency-strain spectra. Mechanical properties have been explored by means of creep, stress-relaxation experiments and stress-strain plots at different strain-rates. Relaxation times and Young's modulus E have been evaluated. The morphology of the samples has been examined by means of optical microscopy. Rheological differences either among air-dried woods, or between air-dried and thermo-treated woods, have been observed. In particular, air-dried wood (and especially Cedrus) shows a significant plastic behaviour. In contrast, the thermo-treatment makes the materials mainly elastic and structurally stable. The plasticity of the air-dried woods seems to be due to the shear of the hemicellulose interface and to plasticizers of lignin matrix; the increased elasticity of the thermo-treateds would be due to the additional lignin cross-linking, and loss of hemicellulose and plasticizers. Air-dried woods, especially the softwood, have a thermoplastic-like behaviour, where the non-bonded intermolecular interactions prevail, in contrast, the thermo-treated woods are thermosetting-like due to the higher degree of cross-link of the polymeric matrix. The study demonstrates the possibility of characterizing wood through viscoelasticity and dynamic mechanical analysis.
机译：通过动态力学分析（DMA）以弯曲模式在30摄氏度下对风干或热处理的雪松deodara和ara木的粘弹性进行了评估。通过频率研究了E-1，E-2和tanδ -应变谱。通过蠕变，应力松弛实验和不同应变率下的应力-应变图来探索机械性能。已经评估了弛豫时间和杨氏模量E。样品的形态已通过光学显微镜检查。已经观察到风干木材之间，风干木材和热处理木材之间的流变学差异。特别是风干的木材（尤其是雪松）表现出显着的塑性行为。相反，热处理使材料主要是弹性的和结构稳定的。风干木材的可塑性似乎是由于半纤维素界面的剪切和木质素基质的增塑剂所致。热处理后的弹性增加归因于额外的木质素交联，以及半纤维素和增塑剂的损失。风干的木材，特别是软木，具有类似热塑性塑料的性能，其中主要存在非键合分子间相互作用，相反，由于聚合基质的交联度较高，因此热处理过的木材呈热固性。该研究证明了通过粘弹性和动态力学分析表征木材的可能性。

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