School of Polymers and High Performance Materials, The University of Southern Mississippi, Hattiesburg, Mississippi 39401, United States.
ACS Appl Mater Interfaces. 2012 Feb;4(2):564-72. doi: 10.1021/am201515y. Epub 2012 Jan 25.
Epoxy-amine resins find wide application as the matrix material of high performance polymer composites because of their favorable mechanical properties, thermal properties and solvent stability. These properties result from the complicated, highly cross-linked molecular network that is characteristic of epoxy-amine thermoset polymers. The connectivity of the molecular network has a strong influence on the physical performance of the finished part. Nonhomogeneity in the network structure can degrade these favorable properties through the introduction of low-energy pathways for solvent penetration or fracture propagation. This work examines the influence of cure temperature on the network-building cross-linking reaction and the subsequent effect on the homogeneity of the cross-linked molecular network. Specific attention is paid to nanoscale variation in the distribution of cross-link density. Thermal, rheological, and spectroscopic techniques are used to monitor key chemical and structural changes during network growth. Atomic force microscopy is used to understand nanoscale fracture behavior in terms of the low energy pathways that result from a nonhomogeneous distribution of cross-link density. The influence of processing-induced changes in molecular connectivity is discussed in terms of observed nanoscale morphology and fracture properties of the cured material.
环氧树脂-胺树脂因其优异的机械性能、热性能和溶剂稳定性而被广泛用作高性能聚合物复合材料的基体材料。这些性能源于环氧树脂-胺热固性聚合物特有的复杂、高度交联的分子网络。分子网络的连通性对成品部件的物理性能有很大的影响。通过引入溶剂渗透或断裂扩展的低能途径，网络结构的非均质性会降低这些有利的性能。本工作研究了固化温度对网络形成交联反应的影响，以及对交联分子网络均匀性的后续影响。特别关注交联密度分布的纳米级变化。热、流变和光谱技术用于监测网络生长过程中的关键化学和结构变化。原子力显微镜用于根据交联密度分布不均匀导致的低能量途径来理解纳米级断裂行为。根据观察到的纳米级形态和固化材料的断裂性能，讨论了加工引起的分子连接变化的影响。
