Role of geometric shapes on the load transfer in graphene-PMMA nanocomposites

In this paper, a series of pull-out simulations of graphene are carried out to investigate the influence of two-dimensional (2D) geometric shapes of graphene nanosheet on the interfacial load transfer in graphene/PMMA nanocomposites by means of molecular dynamics (MD) simulation. Three common types of shapes, i.e. rectangle, trapezoid and sawtooth, are considered. It is found that the drastically improved pull-out force and interfacial shear strength is highly dependent on the 2D geometry and loading direction. By comparison of conventional rectangle-shaped graphene, trapezoidal- and sawtooth-shaped graphene effectively enhance the interfacial load transfer capability. Particularly, as a result of more effective steric-hindrance, pronounced enhancement in the pull-out force is observed when the loading direction is along the rostral-caudal direction of the trapezoidal graphene and the edge waviness of sawtooth-shaped graphene increases. Moreover, pull-out force model characterized by the interfacial shear force generation contacts and the resistance of the blocking zone are proposed to demonstrate the source of pull-out force and interfacial loading transfer mechanism for graphene with different 2D geometries. These findings are importance to better understand the alternative reinforcing mechanism of graphene with various geometric shapes and facilitate the development of mechanically robust graphene/polymer composites.