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Modelling of Deformation Behavior of Micro-Mezo-Macroscopic Scale of Glassy Polymers

玻璃态聚合物微观-介观-宏观尺度变形行为的建模

基本信息

批准号：
07555032
负责人：
TOMITA Yoshihiro
金额：
$ 5.7万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

In the development of a constitutive model of deformation behavior for a glassy polymer, molecular chain network theories have been developed to take account of the strain-induced anisotropy due to the alignment of the molecular chains and the changes in the number of entangled points. However, the suitable constitutive equation which can duplicate the general deformation behavior of polymeric materials and relationship betweenn the micro-and macroscopic behaviors of polymeric materials, that have hierarchical structures at successive molecular to macrolevels, have not been clarified vet.In this work, a new molecular chain network model, nonaffine model, which allows the change in the number of entangled points due to the thermal activation caused by the temperature change and the pullout of the molecular chain from the entangled points by local deformation. An identification method employing both experiments and computational simulation has been developed and thus established constitu … More tive equation has been approved through the computational prediction of experimental results. Furthermore, the peculiar instability propagation behavior observed in the tensile deformation as well as in the shear deformation under different deformation conditions.Next, in order to estabish the hierarchical constitutive model covering the response of molecular structure of mononer leading to deformation on a mezzo-and macroscopic deformation behavior, we applied AFM and clarified the relationship between the micro-and macroscopic behaviors. For highly oriented ultrahigh molecular weight polyethylene, (UHMW-PE), hierarchical structures with scales from microns to angstroms were observed such as microfibril structure aligned along the drawing direction, and nanofibril structure with dozens of nanometers. On the molecular level, regular chain pattern is formed on the surface of the nanofibril structure. The observation of microscopic surface profiles of PC,a glassy polymer, under uniaxial tension with neck propagation has clarified that the formation of microfibril structures aligned along the tensile direction on the surface and the clear delay in the rotation of aligned microfibril structures with rsepect to that of principal direction of plastic stretch due to shear strain, which suggests the necessity of the establishment of the nonassociative frame work for the constitutive equation. Less

在玻璃态聚合物变形行为的本构模型的发展中，分子链网络理论已经发展到考虑由于分子链的排列和纠缠点数量的变化而引起的应变诱导的各向异性。然而，对于具有从分子到宏观层次的分级结构的高分子材料，其微观行为与宏观行为之间的关系，以及能够再现其一般变形行为的本构方程，至今还没有得到很好的解释。本文提出了一种新的分子链网络模型--非仿射模型，其允许由于温度变化引起的热活化而引起的缠结点的数目的变化以及通过局部变形从缠结点拉出分子链。提出了一种采用实验和计算机模拟相结合的辨识方法，并建立了相应的数学模型。 ...更多信息通过对实验结果的计算预测，验证了该方程的正确性。此外，在不同变形条件下，拉伸变形和剪切变形都表现出了独特的失稳传播行为。其次，为了建立包含单体分子结构对变形的响应的分级本构模型，我们应用原子力显微镜（AFM）研究了微观和宏观变形行为之间的关系。对于高度取向的超高分子量聚乙烯（UHMW-PE），观察到了从微米到埃尺度的分级结构，例如沿着拉伸方向排列的微纤维结构和数十纳米的纳米纤维结构。在分子水平上，在纳米纤维结构的表面上形成规则的链图案。对玻璃态聚合物PC在单轴拉伸条件下的微观表面形貌的观察表明，在拉伸过程中，沿拉伸方向沿着排列的微纤结构在PC表面形成，由于剪切应变，沿拉伸方向排列的微纤结构的旋转明显滞后于塑性拉伸的主方向，这表明建立非结合本构方程框架的必要性。少