Molecular Simulation Of Curing Behavior And Network Structure Characteristics Of Epoxy Resin/amine Cured Systems With Different Functionality

Epoxy resins are perfect industrial materials due to their outstanding thermal,mechanical and electrical properties.And an ideal network structure is necessary for high performance resins.So it is essential to investigate the details of various epoxy resins network structure.However,multiple reaction sites between curing agent and epoxy resin matrix lead to complex three-dimensional network structure of epoxy resin system,and the properties of epoxy resin matrix are closely related to its network structure.In the traditional material research methods,there are very few reports on the structure of epoxy resin network,mainly due to the lack of targeted characterization means.However,molecular simulation method can effectively solve this problem.It can understand the structure of crosslinking network from the molecular scale and compare the structural characteristics of different epoxy resin networks.In this paper,molecular simulation technology was used to analyze and study the cross-linking network structures of epoxy resin/amine curing systems with different functional degrees.The specific work is as follows:Around the network formation process of epoxy resin,the reaction between epoxy group and amine group was explored.The visual network structure of the amine curing agent/epoxy system was obtained by using total atomic molecular dynamics(MD)and coarse-grained(CG)method.In order to study the different reactions between epoxy groups and amine groups in the process of cross linking,the distribution of different types of amine groups,curing agents with connection different numbers and the intramolecular and intermolecular radial distribution functions(RDF)were extracted.On this basis,a method was found to express different ring structures of different epoxy resin system networks to summarize the structural characteristics of epoxy resin network,and a standard for the formation of ring structure of epoxy resin system was proposed,in which the shortest ring near the crosslink point was seen as the ring structure of epoxy resin system.A new structural parameter(ring efficiency)was introduced to characterize the elastic contribution of different ring structures to the network by using crosslink points to distinguish loop defects and loop structures.Simulation analysis shows that ring efficiency can be used to compare various rings in different epoxy resin systems.Through the analysis of reaction site and ring structure,the formation process and composition characteristics of different epoxy resin/amine system networks were clearly expressed.