Multiscale simulation study of anisotropic nanomechanical properties of graphene spirals and their polymer nanocomposites

Research on three-dimensional (3D) helical nanomaterials made from base nanotube and nanosheet structures has recently shown tremendous growth due to their outstanding electrical and mechanical properties. Herein, we report the molecular dynamics simulations of graphene spirals to evaluate their anisotropic, or more precisely, transversely isotropic, nanomechanical properties such as the elastic constants in different directions as well as the polymer interphase shape around the nano-spirals in representative volume elements of polyethylene-based nanocomposite materials. The results are presented for different dimensions of the spiral inner and outer radii. According to the outcomes, increasing the width of the graphene nano-coils increases both of their longitudinal and transverse elastic moduli. Furthermore, the 3D finite element models of the representative volume elements are built to analyze the mechanical properties of the nanocomposite materials vs. the volume fraction, geometry, interphase thickness and orientation of nano-fillers inside the matrix. The isotropic and transversely isotropic finite element models of the graphene spirals show considerable differences in the stress-strain diagrams and the elastic moduli of the polymer nanocomposite materials.