The Mechanisms of Crystallization of Copolymers at Atmospheric and Elevated Pressures

常压和高压下共聚物的结晶机制

• 批准号: 9711986
• 负责人: Paul Phillips
• 金额: $ 25万
• 依托单位: University of Tennessee Knoxville
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-15 至 2001-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9711986&HistoricalAwards=false
• 关键词: Mechanisms; Crystallization; Copolymers; Atmospheric; Elevated

9711986 Philllips There are many variables which 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 the research is to understand the ways in which all four of these variables interact in determining the details of the basic physics of the crystallization process in polymers of commercial importance. The synergistic effects of these variables will be investigated for several carefully chosen systems and in doing so will contribute to the education of undergraduate and graduate students. Whereas past work has concentrated on cis-polyisoprene, polyethylene, polypropylene and PET, and their copolymers with comonomers that are rejected from the crystals, recent research has added copolymers of nylon 6,6. This latter group includes a copolymer in which the comonomer is incorporated into the unit cell of the homopolymer. Preliminary results show the behavior of this copolymer to be quite unexpected and different from all others. Research already begun on the very important new copolymers of ethylene and octene made using metallocene catalysts is definitive and shows them to be very different from matched fractions of similar copolymers made using traditional Zeigler Natta type catalysts. For the first time, this research has demonstrated the importance of yet another variable on crystallization behavior, the comonomer sequence length distribution. It is proposed to expand our studies of the random ethylene-octene copolymers and to study them at elevated pressures. In addition studies of the formation of the fascinating Y phase in polypropylene at elevated pressures will be continued and extended to copolymers already studied at atmospheric pressure. Copolymers show this phase at atmospheric pressure despite the fact that it should not be there according to the phase diagram of the homopolymer. It therefore appears that the energetics of its formation are strongly perturbed by the presence of an excludable comonomer. %%% This research will contribute to the understanding of the crystallization behavior of different classes of commercially significant copolymers under conditions of temperature and pressure normally encountered in the molding operations of the plastics industry, whilst at the same time providing both undergraduate and graduate students with valuable laboratory experience. ***

9711986 Phillips 在制造的加工和制造阶段，有许多变量会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、分子量和链微观结构。 该研究的长期目标是了解所有这四个变量在确定具有商业重要性的聚合物结晶过程的基本物理细节时相互作用的方式。 这些变量的协同效应将在几个精心选择的系统中进行研究，这样做将有助于本科生和研究生的教育。 过去的工作主要集中在顺式聚异戊二烯、聚乙烯、聚丙烯和 PET 以及它们与晶体中被剔除的共聚单体的共聚物，而最近的研究添加了尼龙 6,6 的共聚物。 后一类包括其中共聚单体掺入均聚物晶胞中的共聚物。 初步结果表明，这种共聚物的行为非常出乎意料，并且与所有其他共聚物不同。 已经开始对使用茂金属催化剂制成的非常重要的新型乙烯和辛烯共聚物进行的研究是明确的，并表明它们与使用传统齐格勒纳塔型催化剂制成的类似共聚物的匹配部分非常不同。 这项研究首次证明了另一个变量对结晶行为的重要性，即共聚单体序列长度分布。 建议扩大我们对无规乙烯-辛烯共聚物的研究，并在高压下研究它们。 此外，我们将继续研究在高压下聚丙烯中迷人的 Y 相的形成，并将其扩展到已经在大气压下研究的共聚物。 共聚物在大气压下显示出该相，尽管根据均聚物的相图它不应该存在。 因此，似乎其形成的能量受到排他性共聚单体的存在的强烈干扰。 %%% 这项研究将有助于了解不同类别的具有商业意义的共聚物在塑料工业成型操作中常见的温度和压力条件下的结晶行为，同时为本科生和研究生提供宝贵的实验室经验。 ***