Deformation mechanism of graphene in amorphous polyethylene: A molecular dynamics based study

R Rahman and JT Foster, COMPUTATIONAL MATERIALS SCIENCE, 87, 232-240 (2014).

DOI: 10.1016/j.commatsci.2014.02.023

The current paper focuses on investigating deformation mechanism of graphene sheets in a graphene reinforced polyethylene (Gn-PE) nanocomposite. Classical molecular dynamics (MD) simulation was conducted on large Gn-PE systems. Different spatial arrangements of graphene sheets were considered in order to study the effect of nonlocal interaction among the graphenes. In all the cases 5% weight concentration of graphene was considered in order to prepare atomistic models for Gn-PE. As expected, graphene seemed to enhance the overall Young's modulus and tensile strength of the Gn-PE nanocomposite. Randomly oriented graphenes with strong nonlocal interaction were observed to be comparatively preferable than the other spatial arrangements of graphenes. The high strength and stiffness of graphene sheets can be properly utilized if the graphenes are randomly oriented and have strong long range interactions. Finally, the failure mechanism of the graphene and role of voids in the polymer were discussed both qualitatively and quantitatively. It was seen that the randomly oriented graphenes were firstly pulled out from the polyethylene matrix during deformation prior to breaking into pieces. This can explain the loss of stiffness and strength in graphene sheets embedded in the polymer matrix. From the current work it is clearly understood that the necessity of the long range graphene-graphene interaction is important in both elastic as well as plastic regime of the deformation. (C) 2014 Elsevier B.V. All rights reserved.

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