Molecular, Microscopic and Macroscopic Investigation of Fracture in Polymer and Composites

本研究的目的是探索聚合物和聚合物基复合材料断裂的宏观、微观和分子方面。重点将放在定义应力和侵略性环境因子对高取向、超高强度聚合纤维机械性能的协同效应。利用电子自旋共振（ESR）技术对纤维拉伸过程中的键断裂事件进行监测。这些实验将提供应力/老化导致的分子变化的信息，完成最终失效所需断裂的链的数量，以及对样品失效过程中活跃的分子机制的洞察。ESR技术也将用于研究纤维复合材料的失效。ESR光谱将提供应力分布及其与复合材料中纤维破坏的关系的信息。

The goal of this research is to explore the macroscopic, microscopic, and molecular aspect of fracture in polymers and polymeric matrix composites. Particular emphasis will be placed on defining the synergistic effects of stress and aggressive environmental agents on mechanical properties of highly oriented, ultra high strength polymeric fibers. The bond rupture events will be monitored with Electron Spin Resonance (ESR) technique during the fiber tensile tests. These experiments will provide information on molecular changes resulting from stress/ageing, the number of chains that need to be broken to accomplish final failure, and insight into the molecular mechanisms active during sample failure. The ESR technique will also be used to study failure of fiber composites. The ESR spectra will yield information on the stress distribution and its relation to the failure of fibers in the composite.