Towards a computational approach to penetrant diffusion in semicrystalline polymers

Abstract Diffusion of small molecules through semicrystalline polymers is modelled by moving a random-walker on a lattice. The free volume on the lattice represents amorphous polymeric material into which non-percolating polymer crystallites are embedded. These are modelled as impenetrable obstacles. The mobility of the penetrants and its dependence on the density, size and shape of the obstacles is investigated. The diffusion coefficient depends strongly on the shape of the obstacles and not just on their density. With penetrant diffusion coefficients for totally amorphous polymers having become available through molecular dynamics or Monte Carlo simulations, the random-walk method opens the way to an integrated computational approach to penetrant diffusion in partially crystalline polymeric materials.