US-Egypt Cooperative Research: Segmental Orientation and Strain Induced Crystallization in Regular Bimodal Poly (tetramethylene oxide) (PTMO) Elastomers

美国-埃及合作研究：规则双峰聚四亚甲基氧化物 (PTMO) 弹性体中的链段取向和应变诱导结晶

• 批准号: 9605191
• 负责人: James Mark
• 金额: $ 3.6万
• 依托单位: University of Cincinnati Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-04-01 至 2000-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9605191&HistoricalAwards=false
• 关键词: US; Egypt; Cooperative; Research; Segmental

Description: This award is for support of a cooperative project by Dr. James E. Mark and Dr. Gregory Beaucage of the Department of Chemistry at the University of Cincinnati and Dr. M.A. Sharaf, Department of Chemistry, Cairo University at Beni-Suef, Egypt. The main objective of this research is to study factors that influence the important mechanical properties of elastomers. These scientists plan to use functionally capped poly(tetramethylene oxide) (PTMO) oligomers to prepare regular bimodal networks of a mixture of very short chains with relatively long chains, through controlled end linking reactions. In such networks, regularity is ensured by having each junction connected to a constant number of both long and short chains. Improvements in the ultimate properties are due to innate intramolecular effects pertaining to the limited extensibility of short chains. In addition, these particular networks are susceptible to strain-induced crystallization with remarkable consequent improvements in ultimate properties from crystalline reinforcement. The networks so prepared will be employed to better understand the relevant molecular aspects of rubber elasticity, segmental orientation, and strain-induced crystallization. Scope: The combination of data from scattering techniques with those of the modulus, birefringence, and infrared dichroism measurements provides a powerful tool for analysis of the interaction between the size-scale of the complex structural features of both short and the long chains and physical properties in general. Also, mechanical properties and scattering techniques will be employed to investigate both the thermodynamic and kinetic aspects of strain-induced crystallization in these well-characterized elastomeric networks. These studies can result in obtaining elastomers with optimized structure-property relationships through molecular design. The collaboration brings a unique combination of interest and research experiences of the participants from the two countries for improving and optimizing the properties of the economically-important elastomeric materials. This award will also enable a junior US scientist, and a US graduate student, to gain international research experience. The project is well in line with the objectives of the Division of International Programs.

描述：这个奖项是为了支持一个合作项目的詹姆斯E。辛辛那提大学化学系的Mark和Gregory Beaucage博士以及M.A. Sharaf，埃及Beni-Suef开罗大学化学系。 本研究的主要目的是 研究影响弹性体重要机械性能的因素。 这些科学家计划使用功能性封端的聚（四氢呋喃）（PTMO）低聚物，通过受控的末端连接反应，制备非常短的链与相对长的链的混合物的规则双峰网络。在这样的网络中，通过使每个结点连接到恒定数量的长链和短链来确保规则性。 最终性能的改善是由于与短链的有限延伸性有关的固有分子内效应。 此外，这些特定的网络容易受到应变诱导结晶的影响，从而使结晶增强的最终性能得到显著改善。 这样制备的网络将被用来更好地了解橡胶弹性，链段取向和应变诱导结晶的相关分子方面。 适用范围：从散射技术与那些的模量，双折射，和红外二向色性测量的数据的组合提供了一个强大的工具，用于分析的大小规模的复杂的结构特征的短链和长链和物理性质之间的相互作用。 此外，机械性能和散射技术将被用来调查在这些良好的特征弹性体网络的应变诱导结晶的热力学和动力学方面。 这些研究可以通过分子设计获得具有优化结构-性能关系的弹性体。 此次合作将两国参与者的兴趣和研究经验独特地结合起来，以改善和优化具有经济重要性的弹性体材料的性能。 该奖项还将使一名美国初级科学家和一名美国研究生获得国际研究经验。 该项目完全符合国际方案司的目标。