Molecular dynamics predictions of thermomechanical properties of an epoxy thermosetting polymer

This paper reports the thermomechanical properties of a thermosetting polymer formed by curing a DGEBA resin with a Jeffamine D230 agent predicted by molecular dynamics (MD) simulations. A multistep crosslinking approach is used to form the crosslinked network of the thermosetting polymer. The radial distribution function and X-ray diffraction pattern of the MD predicted crosslinked structure are calculated and compared with experimental results to validate the epoxy network system. Thermomechanical properties such as mass density, gel point, glass transition temperature (T_g), elastic moduli (Young's modulus and shear modulus), and yield strength in shear and tension are calculated at different temperatures and crosslinking conversions by employing the DREIDING and AMBER force fields. The MD predicted results are in good agreement with theoretical studies and existing experimental data. We find a significant increase in T_g and yield strength with crosslinking conversion. The elastic modulus is less sensitive to the strain rate, but the yield strength is significantly strain-rate dependent. The high-quality digital epoxy configurations developed in this work are available in LAMMPS data format from the journal website.