Healing and Reprocessing of Epoxy with Dynamic Covalent Bonds and Composites

这笔赠款为研究加工条件与含有动态共价键的聚合物和聚合物复合材料的愈合和再加工之间的关系提供了资金。这些聚合物的一个重要特征是，大分子链的主链可以通过键交换反应断裂和重新连接。虽然这种动态共价反应不会改变聚合物网络的整体拓扑和性质，但从宏观上讲，它们会导致应力松弛和材料焊接。拟议的工作将研究键交换反应动力学和焊接动力学及其对工艺条件的依赖。在实验室中制备了含有动态共价键的环氧树脂样品，并在不同的热机械加载条件下进行测试，以了解温度对键交换反应动力学的影响。这些样品将在不同的热机械加载条件下破碎，然后连接在一起。特殊染料将被加入到聚合物样品中，以便于监测键断裂和重整过程，以及由于键交换反应而导致的物种迁移。通过这些实验，将建立键交换反应动力学、焊接动力学和工艺条件之间的关系。本文还对动态共价键环氧树脂及其复合材料的再加工性进行了研究。环氧树脂和可重塑和可回收的复合材料。本研究的主要目标是建立键交换反应动力学和焊接动力学的基本原理。这些原则可能包括工艺参数，如温度、保持时间、施加压力和表面粗糙度，如何影响环氧树脂的重塑、焊接和再加工能力。确定这些工艺参数将使环氧树脂得到可靠的加工和回收，降低加工成本，并提高产品质量。所建立的原理也可用于包含其他类型的动态共价键的聚合物。

This grant provides funding for the study of the relationship between processing conditions and the healing and reprocessing of polymers and polymer composites containing dynamic covalent bonds. A significant feature of these polymers is that the backbone of the macromolecular chain can break and reconnect through bond exchange reactions. While such dynamic covalent reactions do not change the overall topology and properties of the polymer network, macroscopically they result in stress relaxation and material welding. The proposed work will examine the bond exchange reaction kinetics and welding kinetics and their dependence on processing conditions. Epoxy samples containing dynamic covalent bonds will be prepared in the lab and tested under different thermo-mechanical loading conditions to understand the effects of temperature on the bond exchange reaction kinetics. These samples will be broken then joined together under different thermo-mechanical loading conditions. Special dyes will be incorporated into polymer samples to facilitate monitoring the bond breaking and reforming process, as well as the migration of species due to bond exchange reactions. From these experiments, the relationships between bond exchange reaction kinetics, welding kinetics, and processing conditions will be established. The re-processibility of the dynamic covalent bond epoxy and its composites will also be investigated.If successful, the results from this work will lead to the development of new ?green? epoxy and composites that can be reshaped and recycled. The primary goal of this research is to establish fundamental principles for bond exchange reaction kinetics and welding kinetics. These principles may include how processing parameters, such as temperature, hold time, applied pressure, and surface roughness, can affect reshaping, welding, and re-processibility of the epoxy. Determining these processing parameters will enable robust processing and recycling of the epoxy, reduction in processing cost, and improvement on product quality. The established principles can also be used for polymers containing other types of dynamic covalent bonds.