Kinetic and Structural Properties of Semicrystalline Polyolefins derived from NMR, Thermal Analysis and High Resolution Microscopies

本文介绍了一项研究计划，该计划利用以往在半结晶聚合物领域的经验，并利用核磁共振波谱技术来提高聚烯烃的表征和结构性能。本研究还旨在提高我们对非取向各向同性熔体或先前结晶系统退火过程中晶体结构发展的理解。该项目计划在NSF之前资助的项目的基础上，对固态核磁共振的使用进行培训，扩展一种新的核磁共振方法，以获得以前用其他技术表征的线性聚乙烯窄组分的晶体厚度分布和平均厚度。该方法还将在聚丙烯中使用AFM， SAXS和TEM数据进行测试，以建立所需的校准。NMR， DSC和AFM的结合将用于确定非晶区特定的片层形态和/或链构象的作用，在聚丙烯中观察到的独特的等温熔化。本文还将研究这一过程的动力学。该提案还包括一项研究计划，以评估在退火先前结晶的聚烯烃时随时间发生的结构变化的性质。变化将根据初始结晶形态进行评估。重点介绍了晶间链弛豫性质的核磁共振研究和表征良好的茂金属型聚乙烯和聚丙烯的光晕的WAXS分析。FAMU-FSU工程学院是佛罗里达州立大学和佛罗里达农工大学联合管理的项目，佛罗里达州立大学是一所研究型大学，有35000名学生，佛罗里达农工大学是一所历史悠久的黑人大学，有12000名学生。两所大学的教员都是联合聘任的，两所大学的学生都参加相同的工程课程。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，这在几个方面都是独一无二的。建议的工作包括研究生的积极参与和培训，在当前的技术表征聚合物。这些活动与PI对高分子科学与工程领域学生教育的承诺相一致。PI计划利用最近NSF资助的仪器（核磁共振光谱仪和原子力显微镜）在工程学院的FAMU和FSU扩展表征和新型聚烯烃晶体状态的细节。

A research program is described that uses previous experience in the area of semicrystalline polymers and the use of NMR spectroscopy to advance the characterization and structural properties of polyolefins. The research is also projects to improve our understanding of the development of crystalline structure from the non-oriented isotropic melt or during annealing a previously crystallized system. The PI plans to build upon the base of pervious NSF funded programs that allowed training in the use of solid-state NMR, to extend a novel NMR method to obtain the crystallite thickness distributions and mean average thicknesses of narrow fractions of linear polyethylenes previously characterized with other techniques. The method will also be tested in polypropylenes using AFM, SAXS and TEM data to build the required calibrations. A combination of NMR, DSC and AFM will be used to establish the role of a specific lamellar morphology and/or chain conformation in the amorphous regions, in the unique isothermal melting observed in polypropylenes. The kinetics of this process will be also studied. The proposal also includes a research program to assess the nature of the structural changes that take place with time upon annealing previously crystallized polyolefins. Changes will be evaluated in relation to the initial crystalline morphology. Emphasis is given the NMR investigation of relaxation properties of the chains in the intercrystalline regions and WAXS analysis of the halo of well characterized metallocene type polyethylenes and polypropylenes.%%%The FAMU-FSU College of Engineering is a jointly managed program of the Florida State University, a Research I institution with an enrollment of 35,000, and Florida A&M University, a Historically Black University with and enrollment of 12,000. Faculty hold joint appointments at both institutions, and students from both universities enroll in the same engineering classes. The present enrollment at the College of Engineering consists of approximately 50% minority students and over 25% women, making it unique in several respects. The proposed work includes active participation of graduate students and training in current techniques of characterization of polymers. These activities parallel the commitment of the PI to education of students in the area of Polymer Science and Engineering. The PI plans to take advantage of recently NSF funded instrumentation (NMR spectrometer and AFM) to FAMU and FSU at the College of Engineering to expand on characterization and the details of the crystalline state of novel polyolefins.