Mesoscopic simulations for the molecular and network structure of a thermoset polymer

Meso-scale simulations are performed to obtain a fully cross-linked, equilibrated structure of an epoxy network. We derive and study the interactions giving rise to the final structure. Both equilibrium structures with no cross-links and fully cross-linked are examined. The simulations were performed using a recent dissipative particle dynamics parameterization method in which beads attain their pure volumes in the final structure. Preferential attractive and repulsive behavior of different chemical functional groups is revealed. When those are simulated as monomers, two phases form where intra-bead interactions are attractive and inter-bead interactions are repulsive. A homogeneous density distribution over the simulation box is noticed when simulated as chains. The network properties are characterized as well. The cross-link conversions are analyzed which show that the bead type consisting of initially primary amines have the highest value. Moreover, different cross-link formation rates for secondary amines are incorporated in the simulations and effects on the structure and conversion are discussed.