Co-authors​ :

 Jia-Lin JIA-LIN TSAI (TAIWAN), Po-Ying PO-YING TSENG  

The study aimed to characterize the mechanical behaviors of graphene nanocomposites using molecular dynamics (MD) simulation. Both monolayer graphene and multilayer graphene were considered as reinforcement in the epoxy matrix. The influences of surface functionalization and graphene waviness on the behaviors of the nanocomposites were also examined. In the MD simulation, the Polymer Consistent Force Field (PCFF) potential [1] which was commonly employed in polymer materials was adopted to describe the bonded and non-bonded interactions of the atoms and molecular in the graphene nanocomposites. The simulations were conducted using the Large-scale Atomic/Molecular Massively Parallel Simulation (LAMMPS) software [2]. In order to explore the load transfer efficiency between the graphene and the surrounding matrix, the local stress of the graphene was calculated using Lutsko stress formulation [3, 4]. On the other hand, the global stress of the nanocomposites was calculated using Virial stress formulation [5]. Moreover, the pullout simulations were also carried out to characterize the interfacial behavior of the graphene and the epoxy matrix. The results indicated that the increase in the number of graphene layers reduced the Young's modulus of the nanocomposite, which was mainly attributed to the low load transfer efficiency of the graphene inner layer. The pullout simulation revealed that the interfacial shear stress of the multilayer graphene was lower than that of the monolayer graphene. Graphene surface functionalization can effectively improve the load transfer efficiency between graphene and epoxy matrix, thereby improving the Young's modulus of the nanocomposites, wherein the enhancement of the outermost layer is more significant than the inner layer. In addition, the phenomenon that wavy graphene would dramatically reduce the Young's modulus of the graphene nanocomposite was observed in our simulation.
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