Crystallization Behavior and Structural Properties of Model Semicrystalline Polyolefins

本研究计划的主要目的是提高对无取向体结晶柔性链聚合物的热力学、动力学和结构性质的理解。在建立描述结晶状态和最终性质的重要独立结构变量的基础上，研究计划被描述为推进对链微观结构，相结构，结晶动力学和主要类别的结晶聚合物聚烯烃形态之间相互作用的理解。重点是模型支化聚乙烯的新研究，作为控制微观结构，以建立分子结构和它们组装的半结晶形态之间的联系。对两组模型支化聚乙烯进行了研究。一组精确间隔的支链聚乙烯在短链分子的结晶和更复杂的工业性质的线性低密度聚乙烯之间起着桥梁作用。第二组模型长链支链（LCB）随机乙烯共聚物将为LCB的长度和结构对来自各向同性熔体的这些聚乙烯的结晶行为的影响提供基础，在流动固有的额外影响开始发挥作用之前。这些系统结晶的早期阶段的细节作为描述h链和其他类型的LCB聚丙烯的性质的基础，也是本提案的研究主题。模型系统的工作将为佛罗里达大学和FAMU-FSU工程学院的教师和学生提供一个机会，使他们能够密切互动，以整合催化，大分子结构及其超越每个小组实验室边界的有序状态。该提案还包括详细的工作，以证实Z-N基等规聚丙烯的缺陷微观结构模型，源自先前的研究，以及茂金属无规丙烯聚合物结晶行为的延续。在这个场地的重点是给予整合在整体结晶和这些共聚物的线性增长的分析多晶态行为的动力学。FAMU-FSU工程学院是佛罗里达州立大学（florida State University）和佛罗里达农工大学（florida a&m University）联合管理的项目。佛罗里达州立大学是一所研究型大学，有3.8万名学生，佛罗里达农工大学是一所历史悠久的黑人大学，有1.2万名学生。两所大学的教师都是联合聘任的，两所大学的学生都参加了相同的工程课程。目前，工程学院的学生中约有50%是少数民族学生，超过25%是女性，这在很多方面都是独一无二的。建议的工作包括研究生和本科生的积极参与，以及当前聚合物表征技术的培训。这些活动与PI在聚合物科学与工程领域教育学生的承诺相一致。

The main objective of this research proposal is to improve understanding of thethermodynamic, kinetic and structural properties of non-oriented bulk crystallizedflexible chain polymers. Building on a foundation that established the importantindependent structural variables that describe the crystalline state, and final properties, aresearch program is described to advance the understanding of the interplay betweenchain microstructure, phase structure, crystallization kinetics and morphology of thedominant class of crystalline polymers, the polyolefins. Emphasis is given to novelstudies of model branched polyethylenes that serve as control microstructures to establishthe connection between molecular architecture and the semicrystalline morphology thatthey assemble. Two sets of model branched polyethyelenes will be studied. One set ofprecisely spaced branched polyethylenes serve as a bridge between the crystallization ofshort-chain molecules and the more complex behavior of industrial-like linear lowdensity polyethylenes. The second set of model long chain-branched (LCB) randomethylene copolymers will provide fundamentals for the effect of length and architectureof LCB on the crystallization behavior of these polyethylenes from isotropic melts,before additional effects intrinsic to flow, come into play. Details of the early stages ofthe crystallization of these systems serve as a basis to describe the properties of H-linkand other types of LCB poly(propylenes) also subjects of study in this proposal.The work on model systems will provide an opportunity for faculty and studentsof the University of Florida and the FAMU-FSU College of Engineering to interactclosely toward integrating catalysis, macromolecular architecture and their path to theordered state beyond each group's laboratory boundaries.The proposal also includes detailed work to substantiate a model of defectmicrostructure for Z-N based isotactic poypropylenes, derived from previous studies, aswell as a continuation of the crystallization behavior of metallocene random propylenecopolymers. In this venue emphasis is given to integrate the dynamics of thepolymorphic behavior in the analysis of the overall crystallization and the linear growthrates of these copolymers. The FAMU-FSU College of Engineering is a jointly managed program of theFlorida State University, a Research I institution with an enrollment of 38,000 andFlorida A&M University, a historically Black University with an enrollment of 12,000.Faculty hold joint appointments at both institutions, and students from both universitiesenroll in the same engineering classes. The present enrollment at the College ofEngineering consists of approximately 50% minority students and over 25% women,making it unique in a number of respects. The proposed work includes activeparticipation of graduate and undergraduate students and training in current techniques ofcharacterization of polymers. These activities parallel the commitment of the PI toeducation of students in the area of Polymer Science and Engineering.