Coarse-grained molecular modeling of composite interfaces

Abstract

The interface of fiber and matrix strongly influences the performance and strength of fiber-reinforced composite materials. Due to the limitations of continuum mechanics at the nanometer length scale, atomistic level computer simulation has started to play an important role in the understanding of such interfacial systems. Our study focuses on a typical crosslinked interfacial system of glass-epoxy composite with the presence of silanes. To explore the mechanical properties of the interfacial network system, Coarse-grained Molecular Dynamics is used. Currently it is not possible to study mechanical properties of interfacial systems purely through ab initio molecular dynamics simulations because of the huge computational resources required. Although pure atomistic classical molecular dynamics simulations have been used to study systems comprising billions of atoms, classical MD simulation do not take into account the effects of crosslinking of molecular chains. A new force field, which combines the Lennard-Jones potential and a finite-extensible nonlinear elastic attractive potential, is proposed and incorporated in a bead-spring model to simulate glass/epoxy interfacial system with the crosslinked structure of silanes. The finite-extensible nonlinear elastic attractive potential is included to control the motion and breakage of polymer chains. Interfacial adhesion and mechanical properties were studied through the simulation of mechanically separating the interfacial system.