Relaxation Dynamics of Multiarm Polymer Liquids

多臂聚合物液体的弛豫动力学

• 批准号: 0237052
• 负责人: Lynden Archer
• 金额: $ 33万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-11-01 至 2005-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0237052&HistoricalAwards=false
• 关键词: Relaxation; Dynamics; Multiarm; Polymer; Liquids

Experimental studies of stress relaxation dynamics of well-defined branched polymer liquids have long been recognized as important for understanding structure-processing relationships in commercial long-chain branched polyolefins. When these studies are performed using well-characterized entangled branched polymers they can provide direct insight into more general relationships between molecular architecture, relaxation dynamics, and rheology. The objective of the proposed research is three-fold. First, to determine the effect of branch point motion and constraint release on the linear rheology of model branched polymers. Second, to advance fundamental understanding of nonlinear rheology of entangled branched polymer liquids in shear and extensional flow. Finally, to devise methods for visualizing motion and stress relaxation processes in branched polymer liquids. Benefits of the proposed research extend beyond its direct impact on scientific understanding of branched polymer dynamics. The research, for example, addresses a problem of considerable industrial importance at a time when advances in metallocene catalyst chemistry are allowing unprecedented control of molecular architecture in commercial branched polymers. Fundamental understanding of structure-processing relationships in these materials will help reduce expensive trial-and-error experimentation now required to optimize existing processes for new materials. The proposed research also comes at a time when the first rigorous treatments of architecture effects on polymer processing and properties are beginning to appear in textbooks. This research will impact education in a variety of ways. Knowledge developed by study will improve the quality and scope of information about branched polymer physics written in text books and taught in the classroom. The proposed fluorescence microscopy experiments using branched DNA will also provide an excellent demonstration tool for modern courses in polymer science. Finally, the graduate and undergraduate student researchers who will work on the project will receive training in several emerging areas of polymer science and engineering.

定义明确的支化聚合物液体的应力松弛动力学的实验研究一直被认为是重要的理解在商业长链支化聚烯烃的结构-加工关系。当这些研究进行使用良好的特征纠缠支化聚合物，它们可以提供更一般的分子结构，松弛动力学和流变学之间的关系的直接洞察。拟议研究的目标有三个方面。首先，确定分支点运动和约束释放对模型支化聚合物的线性流变学的影响。第二，推进对缠结支化聚合物液体在剪切和拉伸流动中的非线性流变学的基本理解。最后，设计方法可视化运动和应力松弛过程中支化聚合物液体。拟议研究的好处超出了其对支化聚合物动力学的科学理解的直接影响。例如，当茂金属催化剂化学的进步允许前所未有地控制商业支化聚合物的分子结构时，这项研究解决了一个具有相当工业重要性的问题。对这些材料的结构-加工关系的基本理解将有助于减少昂贵的试错实验，现在需要优化新材料的现有工艺。这项拟议中的研究也是在第一次严格处理结构对聚合物加工和性能的影响开始出现在教科书中的时候。 这项研究将以各种方式影响教育。通过学习开发的知识将提高教科书和课堂教学中有关支化聚合物物理学的信息的质量和范围。建议使用分支DNA的荧光显微镜实验也将为高分子科学的现代课程提供一个很好的演示工具。最后，将参与该项目的研究生和本科生研究人员将接受聚合物科学和工程几个新兴领域的培训。