Molecular dynamics simulation study of parallel orientation structure and gas transport in graphite-nanoplatelet/polyethylene composites

Abstract Molecular dynamics simulations of graphite-nanoplatelet/polyethylene composites have been implemented to investigate the morphological structure and gas transport property by calculations of dynamical energy, structural parameter, X-ray scattering spectrum and gas diffusion coefficient, analyzing their relationship with nanofiller concentration and temperature. The graphite-nanoplatelet/polyethylene composites represent as two-dimensional anisotropic structures with the graphite-nanoplatelets orientating in parallel to each other and composite with polyethylene matrix by intense Van der Waals force and CH-π bonding on nanoplatelet surface, causing a few ordered atomic layers of polyethylene at interface while the internal polyethylene matrix retaining isotropic amorphous morphology. Due to the nanocomposite effect, gas transport in graphite-nanoplatelet/polyethylene composites is significantly affected by the nano-interfaces and orientation of graphite-nanoplatelets without gas selectivity for percolation. The graphite nanocomposites present two-dimensional anisotropic permeation of nitrogen, oxygen and carbon dioxide molecules that the diffusion coefficients are 4 and 7 times higher along orientation plane than in perpendicular direction of graphite-nanoplatelets for 10.4% and 20.4% filler concentrations respectively, suggesting reasonable material application to the gas barrier and percolation control.