Thermodynamic and mechanical properties of EPON 862 with curing agent DETDA by molecular simulation

Abstract

Fully atomistic molecular dynamics (MD) simulations were used to predict the properties of EPON 862 cross-linked with curing agent DETDA, a potentially useful epoxy resin for future applications of nanocomposites. The properties of interest were density (at nearambient pressure and temperature), glass transition temperature, bulk modulus, and shear modulus. The EPON molecular topology, degree of curing, and MD force-field were investigated as variables. The range of molecular weights explored was limited to the oligomer region, due to practical restrictions on model size. For high degrees of curing (greater than 90%), the density was found to be insensitive to the EPON molecular topology and precise value of degree of curing. Of the two force-fields that were investigated, cff91 and COMPASS, COMPASS clearly gave more accurate values for the density and moduli as compared to experiment. In fact, the density predicted by COMPASS was in excellent agreement with reported experimental values. However, the bulk and shear moduli predicted by simulation were about two times higher than the corresponding experimental values.