Molecular dynamics study on mechanical properties of helical graphenes/epoxy nanocomposites

Helical graphenes (HGs) have attracted much attention due to its excellent electrical and mechanical properties, and provide an ideal nanofiller for the preparation of novel functional epoxy resin matrix composites.The mechanical properties of HGs/epoxy resin composites (marked as HGs/epoxy) are investigated by molecular dynamics (MD) simulations and compared with those of pure epoxy resin systems (referred to as epoxy).The results show that HGs/epoxy systems have higher Young's modulus and yield strength than pure epoxy systems with the same crosslinking degree.Interestingly, the strengthening effect of HGs on the epoxy systems with low crosslinking degree is more obvious. The Young's modulus of the HGs/epoxy system with 40% crosslinking degree increase by 55.73%, 53.82% and 48.61% along the X, Y, Z directions, respectively.For the HGs/epoxy system with 60% crosslinking degree, the yield strengths increase by 36.64%, 26.69% and 43.39% along three directions, respectively. The enhancement of the overall mechanical properties for the HGs/epoxy systems is mainly attributed to the entanglement between molecular chains and HGs. Especially when the molecular chains are wound around adjacent coils of HGs,the binding energy between the matrix and reinforcement is greater,and the system exhibits better mechanical properties and more obvious mechanical anisotropy.These results provide the theoretical support for the preparation of novel epoxy resin matrix composites.