Molecular dynamics for the prediction of the interfacial shear stress and interface dielectric properties of carbon fiber epoxy composites

The thermoset epoxy resin Diglycidyl ether of Bisphenol F (EPON 862), crosslinked with the Diethylene Toluene Diamine (DETDA) hardening agent, are utilized as the polymer matrix component in many graphite (carbon fiber) composites. Since it is difficult to experimentally characterize the interfacial region, computational molecular modeling is a necessary tool for understanding the influence of the interfacial molecular structure on bulk-level material properties. The purpose of this research is to evaluate and compare the interfacial shear stress and dipole moment for the pristine carbon fiber composite and the one with the moisture content at the interface. Molecular models are established for Carbon fiber reinforced EPON 862-DETDA polymer with and without the moisture content at the interface. Interatomic interactions are defined by Reactive Force Field (ReaxFF). Material characteristics such as polymer mass-density and dipole moment are investigated near the polymer/fiber interface. It is determined that a region exists near the carbon fiber surface in which the polymer mass density and dipole moment are different than that of the bulk values. It can further be seen that material having larger values of dipole moment in interface region have comparatively lesser values of interfacial shear stress.