Subglass Relaxation Processes in Polymers

聚合物中的亚玻璃弛豫过程

• 批准号: 9302393
• 负责人: Richard Boyd
• 金额: $ 27万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-06-15 至 1996-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9302393&HistoricalAwards=false
• 关键词: Subglass; Relaxation; Processes; Polymers

The details of the molecular mechanisms underlying subglass relaxations in amorphous polymers remain largely a mystery. Although there is a considerable body of useful experimental description, the experiments are rarely specific in revealing the nature of the motions taking place. Molecular modelling or simulation is becoming of increasing value in interpreting the details of molecular motion. An important recent advance has the been the ability to generate, via molecular dynamics (MD) simulation, detailed description of the structure and packing in amorphous polymeric melts and glasses. In the present work, such advances in modelling will be exploited in describing subglass relaxations. The work will be done in association with dielectric relaxation experiments. Systems to be studied include subglass processes in main-chain liquid crystalline aromatic polyesters; subglass processes in other aromatic polyesters; the gramma- relaxation in polyethylene; subglass processes that are, by design, at very low temperature by virtue of low internal rotational barriers; and, side-chain mesogen liquid crystalline polymers. Unlike many other materials, such as metals and ceramics, the usefulness of all polymeric materials depends on the fact that they are very dynamic on the molecular scale. That is, the constituent molecules are in a constant state of motion and the kinds of motion determine the properties. Even in polymers that are apparently rigid and glass-like, residual molecular motions determine such behavior as strength and toughness. However there is not yet a clear understanding of these motions. The present work is directed toward attaining this understanding in order that better materials can be developed. Modern computer modelling techniques will be combined with sophisticated experimental tools in accomplishing this goal.

亚玻璃的分子机制细节 无定形聚合物中的弛豫在很大程度上仍然是一个谜。 虽然有相当多的有用的实验 描述，实验很少具体揭示 所发生的运动的性质。 分子建模或 模拟在解释 分子运动的细节 最近的一项重要进展是， 通过分子动力学（MD） 仿真，详细说明了结构和包装中 无定形聚合物熔体和玻璃。 在目前的工作中， 模型的进步将被用来描述亚玻璃 放松 这项工作将与电介质有关 放松实验 待研究的系统包括亚玻璃 主链液晶芳香族聚酯的工艺; 其他芳香族聚酯的亚玻璃化工艺; 聚乙烯的松弛;亚玻璃工艺，通过设计， 在非常低的温度下，由于低的内部旋转， 阻挡层;和侧链液晶基元液晶聚合物。 与许多其他材料（如金属和陶瓷）不同， 所有聚合物材料的有用性取决于以下事实： 它们在分子尺度上非常活跃。 也就是 组成分子处于恒定的运动状态， 运动的种类决定了性质。 即使在聚合物中， 显然是刚性的玻璃状的残余分子运动 决定强度和韧性等性能。 然而 对这些运动还没有一个清晰的认识。 本 工作的目的是为了达到这种理解， 可以开发出更好的材料。 现代计算机建模 技术将与复杂的实验工具相结合， 来实现这一目标。