Space available to small diffusants in polymeric glasses: Analysis of unoccupied space and its connectivity

Given a diffusant, modeled as a hard sphere, and a microstructure representative of a glassy polymer, represented as a rigid matrix of hard sphere atoms, a quantitative determination of the unoccupied space in the polymer was achieved by applying a Delaunay tessellation of space to available glassy microstructures of atactic polypropylene and bisphenol‐A‐polycarbonate. A description is also given of how local portions of unoccupied space are distributed and interconnected across a polymeric matrix. The shape and dimensions of clustered portions of unoccupied space were analyzed. A visualization of these clusters indicated significant differences, depending on the nature of the diffusant.