The Relation Between Atomic, Molecular Level and Macroscopic Descriptions of Stress in Dense Polymer Systems

9908025目标是发展聚合物系统中应力产生和松弛的统一图景，这将在原子和分子水平上进行尺度连接，并将提供一个框架，其中在更大尺度上定义的本构律将基于原子尺度过程。聚合物工业在试图从聚合物熔体的分子结构预测其加工行为时所面临的挑战激发了这一努力。即将发展的新的物理图景将统一描述与局部原子重排有关的快速弛豫模式，以及与键和链段重定向有关的较慢的短时间模式，将明确地纳入考虑排除体积效应的链内和链间相互作用，并将导致适当的标度定律。这种形式同样适用于短链和长链系统。此外，为了有效地解释宏观描述中的原子尺度细节，这种描述必须采用一种适合于合并到类连续模型中的格式。

9908025The objective to develop a unified picture of stress production and relaxation in polymeric systems which will scale-link the atomic and molecular levels and will provide a framework in which the constitutive laws defined at larger scales will be based on atomic-scale processes. This effort is motivated by the challenges that the polymer industry faces when attempting to predict the processing behavior of a polymer melt from its molecular structure. The new physical picture to be developed will unify the description of the fast relaxation mode, which is related to local atomic rearrangements, and that of the slower short-time modes, which are related to bond and chain segment reorientation, will explicitly incorporate both intra-and inter-chain interactions accounting for excluded volume effects, and will lead to appropriate scaling laws. This formalism will be equally valid for short and long chain systems. Further, this description has to be in a format suitable for incorporation in continuum-like models in order to efficiently account for atomic-scale details within such macroscopic descriptions.