Subcontinuum Interpretation of Mechanical Behavior for Cross-Linked Epoxy Networks

The origin of the mechanical properties of highly cross-linked epoxy networks was theoretically investigated from a subcontinuum perspective. By use of all-atom molecular dynamics (MD) simulations, the macromolecular network of epoxy formed during the cross-linking reactions was classified into subgroups according to their bonding relationship. The deformation energy density applied to the entire system under mechanical loading is expressed by the contribution of each subgroup. The load transfer capabilities according to the chemical bonding state between resin and hardener were then quantified at the atomic level. On the basis of the results, an analytic blending model was established that can predict mechanical properties of the cross-linked epoxy according to its chemical composition and associated network topology. It was confirmed that the proposed model successfully predicts the mechanical properties of materials for the range of composition ratios that can be considered in actual synthesis as well as an in-depth analysis of the individual molecular components.