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

来自 NMR、热分析和高分辨率显微镜的半结晶聚烯烃的动力学和结构特性

• 批准号: 0094485
• 负责人: Rufina Alamo
• 金额: $ 32万
• 依托单位: Florida Agricultural and Mechanical University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-01-15 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0094485&HistoricalAwards=false
• 关键词: Kinetic; Structural; Properties; Semicrystalline; Polyolefins

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.

描述了一项研究计划，该计划利用以前在半结晶聚合物领域的经验和使用核磁共振光谱来改进聚烯烃的表征和结构性质。这项研究还旨在提高我们对无取向各向同性熔体或在退火过程中先前结晶系统的晶体结构发展的理解。PI计划建立在以前NSF资助的项目的基础上，这些项目允许培训使用固态核磁共振，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的窄组分的微晶厚度分布和平均厚度。该方法还将使用AFM、SAXS和TEM数据在聚丙烯中进行测试，以建立所需的校准。核磁共振、差示扫描量热仪和原子力显微镜将被用来确定无定形区域中特定的片层形态和/或链构象在聚丙烯中观察到的独特的等温熔融中所起的作用。并对该过程的动力学进行了研究。该提案还包括一项研究计划，以评估先前结晶的聚烯烃在加热时随时间发生的结构变化的性质。将评估与初始晶体形态相关的变化。重点是对晶间链弛豫性质的核磁共振研究和对茂金属聚乙烯和聚丙烯晕环的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的联合管理项目，佛罗里达州立大学是一所研究I机构，注册人数为3.5万人，佛罗里达农工大学是一所历史悠久的黑人大学，注册人数为12000人。两所大学的教职员工实行联合聘任，两所大学的学生参加相同的工程学课程。工程学院目前招收的学生中约有50%是少数族裔学生，25%以上是女性，这在几个方面是独一无二的。拟议的工作包括研究生的积极参与和当前聚合物表征技术的培训。这些活动与PI对聚合物科学和工程领域的学生教育的承诺同时进行。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)，向工程学院的FAMU和FSU扩展新型聚烯烃的表征和结晶状态的细节。