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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

在建立玻璃态聚合物变形行为本构模型的过程中，发展了考虑分子链排列和纠缠点数目变化引起的应变诱导各向异性的分子链网络理论。然而，可以复制聚合物材料一般变形行为的合适的本构方程，以及具有连续的分子到宏观层次的分级结构的聚合物材料的微观和宏观行为之间的关系，还没有被阐明。在本工作中，一个新的分子链网络模型，非仿射模型，允许由于温度变化引起的热激活而改变纠缠点的数目，以及通过局部变形从缠结点上拔出分子链。提出了一种实验和计算机仿真相结合的辨识方法，从而建立了…系统通过对实验结果的计算预测，验证了更为合理的方程。此外，在拉伸变形和剪切变形中观察到了不同变形条件下特殊的失稳扩展行为。其次，为了建立涵盖单体分子结构在中宏观变形行为上的响应的分层本构模型，我们应用原子力显微镜，阐明了微观行为和宏观行为之间的关系。对于高度取向的超高相对分子质量聚乙烯(UHMW-PE)，观察到了微米到埃的分级结构，如沿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，纳米纤维结构的表面形成了规则的链状图案。通过对玻璃化聚合物PC在单轴拉伸和颈展条件下的微观表面轮廓的观察，阐明了表面沿拉伸方向排列的微纤维结构的形成和由于剪切应变而与塑性拉伸主方向垂直的排列的微纤维结构旋转的明显延迟，这表明建立本构方程的非缔合框架是必要的。较少