高取向聚合物分子取向度与结晶度的各向异性

聚合物分子具有内部各向异性的物理特性,从而导致聚合物整体在大分子取向时呈现各向异性.为克服形态学超分子结构在评价这一特性时带来的误差,作者通过胶凝/结晶作用,制取超拉伸聚乙烯和聚丙烯薄膜,使之具有近乎完美的分子取向度及结晶度的形态,可以使得测量结果更为精确。利用广角X射线衍射(WAXD),直接测定了高取向聚乙烯和聚丙烯的结晶格子模量。在此基础上,测量并讨论了高取向聚合物结晶格子模量与杨氏模量、取向度、结晶度、温度之间的相互关系,以及在晶体色散研究中的一些现象与机理,从而澄清了聚乙烯与聚烯内部各向异性的几个特征。同时还研究了超拉伸聚乙烯的动态弹性模量、动态损耗模量和凝胶薄膜的力学性能。

Intrinsic Anisotropy of Highly Oriented Polymeric Systems in Relation to Molecular Orientation and Crystallinity

Polymer molecules are intrinsically anisotropic in physical properties. This causes the bulk properties of polymer aggregates to be anisotropic when the macromolecules are oriented. In order to overcome the effects caused by the complex morphology with superstructures, a simple mor-phology with perfect molecular orientation and crystallinity can be achieved by using ultradrawn polyethylene and polypropylene films prepard from gelation/crystallization. Thus the estimation of the intrinsic anisotropy of polymeric systems would be correct. On the basis of using X-ray diffrac-tion to determine the crystal lattice modulus of highly oriented polyethylene and polyproylene films directly, this paper discussed the relation between crystal lattice modulus and Young' s modulus, and other characteristics such as orientation, crystallinity and temperature. In addition, this paper refered to several phenomena and mechanisms in the research of crystal dispersions. Thereby several intrinsic anisotropical properties of polythylene and polypropylene were clarified. Moreover, this pa-per also studied the dynamic elastic modulus, dynamic loss modulus and mechanical properties of gel films.