Large-Scale Molecular Dynamics Elucidates the Mechanics of Reinforcement in Graphene-Based Composites

Abstract

Using very large-scale classical molecular dynamics, the mechanics of nano-reinforcement of graphene-based nanocomposites are examined. Simulations show that significant quantities of large, defect-free, and predominantly flat graphene flakes are required for successful enhancement of materials properties in excellent agreement with experimental and proposed continuum shear-lag theories. The critical lengths for enhancement are approximately 500 nm for graphene and 300 nm and for graphene oxide (GO). The reduction of Young's modulus in GO results in a much smaller enhancement of the composite's Young's modulus. The simulations reveal that the flakes should be aligned and planar for optimal reinforcement. Undulations substantially degrade the enhancement of materials properties.

Keywords: graphene; graphene oxide; molecular simulations; polymer nanocomposites; shear-lag models.