Effects of morphologies of carbon nanofillers on the interfacial and deformation behavior of polymer nanocomposites – A molecular dynamics study

Carbon based nanofillers such as carbon nanotube (CNT), carbon nanofiber (CNF) and graphene nanoplatelet (GNP) have emerged as new potential filler materials for tailoring the material properties of composites at the molecular level. The objectives of this study were to understand the effects of morphologies of different types of nanofillers on the interfacial and bulk deformation behaviors of polymer nanocomposites and the inter-correlations between these behaviors. Molecular dynamics simulations were used to achieve the research objective. It was demonstrated that, due to the mechanical interlocking induced by its serrated surface, CNF was most effective in shear traction transfer and offered largest sliding resistance at the filler/matrix interface. The smooth surface of CNT and GNP resulted in poor resistance to sliding separation, but, unlike CNT and CNF, GNP could resist normal separation and had an interfacial normal strength that was higher than the shear strength. Both the interfacial and bulk mechanical behaviors were demonstrated to be a manifestation of the morphologies of the nanofillers, their orientation with respect to the loading direction, the loading mode, i.e., tension vs. compression, and the deformation-induced rotation of the nanofillers.