Molecular dynamics approach on the hygroelastic behavior of epoxy/graphene nanocomposites

Hygroscopic aging causes swelling, degradation of mechanical and interfacial properties in thermosetting epoxy polymers, which eventually lead to a fast fracture at the interface in nanocomposite. Since the epoxy is a widely used high performance thermoset polymer for aerospace structures, durability analysis is necessary for the sake of maintenance and stability of the structures. In this study, the hygroelastic behavior of pure epoxy and epoxy/graphene nanocomposite is investigated through atomistic molecular dynamics (MD) simulation. To determine the hygroelastic behavior of epoxy materials, amorphous molecular unit cells of pure epoxy and epoxy/graphene nanocomposites with its highest possible cross-linking ratio and moisture contents of 0 and 2 wt% are considered. Through the classical ensemble simulations, diffusion coefficient of water in matrix, coefficient of moisture expansion (CME) and elastic modulus of pure epoxy and epoxy/graphene nanocomposites are determined.