The Influences of Chemical Microstructure and Pressure on the Mechanisms of Crystallization in Polymers

在制造的加工和制造阶段，有许多变量影响结晶聚合物的物理和机械性能。其中最重要的四个是温度、压力、分子量和链的微观结构。本研究的长期目标是了解所有这四个变量在确定结晶过程细节时相互作用的方式。在过去工作的基础上，将对几个精心选择的系统研究这些变量的协同效应。尽管过去的大部分工作集中在顺式聚异戊二烯、聚乙烯和聚丙烯上，但拟议的研究将继续涉及聚丙烯及其与乙烯的共聚物。它将引入尼龙- 6,6共聚物作为一个新的基团。后一组将允许更广泛的共聚物结构被考虑；特别是，将会有一系列共聚物，其中有证据表明共聚物被纳入均聚物的单元胞中。这项研究将允许对结晶理论进行定量比较，并使我们能够以彻底的方式研究现有的共聚物结晶理论。这项研究将帮助我们解开前面提到的一些复杂的协同作用。此外，我们将继续研究聚丙烯中伽马相在高压下形成的细节，以及控制其与α相平衡的条件。并期望将这一研究扩展到聚丙烯共聚物。共聚物的研究是研究聚合物中关键次级核的少数可用方法之一，许多结果将用于阐明关于聚合物中结晶的重要物理特征的更多信息。这项研究，通过研究重要聚合物的结晶行为，将提供一个更彻底的理解如何形态影响观察到的体积性质。

Phillips There are many variables that influence the physical and mechanical properties of crystalline polymers through the processing and fabrication stages of manufacture. Four of the most important are temperature, pressure, molecular weight, and chain microstructure. The long-term objective of this research is to understand the ways in which all four of these variables interact in determining the details of the crystallization process. Building on past work, the synergistic effects of these variables will be investigated for several carefully chosen systems. Whereas much of past work has concentrated on cis-polyisoprene, polyethylene, and polypropylene, the proposed research will continue with polypropylene and its copolymers with ethylene. It will introduce copolymers of nylon- 6,6 as a new group. This latter group will permit a wider range of copolymer structures to be considered; in particular, there will be available a series of copolymers in which there is evidence for the comonomers being incorporated into the unit cell of the homopolymer. The research will permit a quantitative comparison to be made of crystallization theories and will enable us to look in a thorough manner at the existing theories of copolymer crystallization. The research will help us unravel some of the aforementioned complicated synergisms. In addition we will continue to investigate the details of the formation of the gamma phase in polypropylene at elevated pressures and the conditions governing its equilibrium with the alpha phase. It is also expected that this research will extend to the copolymers of polypropylene. The study of copolymers is one of the few methods available for the study of the critical secondary nucleus in polymers and many of the results will be applied to elucidating more information on this least explored of the important physical features of crystallization in polymers. %%% This research, by studying the crystallization behavior of important po lymers, will provide a more thorough understanding of how morphology influences observed bulk properties.