Routine million-particle simulations of epoxy curing with dissipative particle dynamics

Mesoscale simulation techniques have helped to bridge the length and time scales needed to predict the microstructures of cured epoxies, but the prohibitive computational cost of simulating experimentally relevant system sizes has limited their impact. In this work we develop an open-source plugin for the molecular dynamics code HOOMD-Blue that permits epoxy crosslinking simulations of millions of particles to be routinely performed on a single modern graphics card. Using these capabilities, we are able to use ensembles of epoxy processing pathways to obtain realistic bond kinetics and relaxation times that sensitively depend on stochastic bonding rates and a diffusive drag parameter. This work also demonstrates the first implementation of fully customizable temperature-time curing profiles with dissipative particle dynamics. Finally, we evaluate the ability of this model to predict the mechanical properties that result from a variety of curing profiles and chemistries for a classic epoxy/hardener/toughener system and quantify the relationship between the temperature-time curing profile and resultant molecular microstructure.