(290g) Diffusion in Polystyrene: a Multi-Scale Approach

Gas diffusion through polystyrene foams has not been thoroughly investigated thus far. Although some early macro-scale models exist for prediction of foam diffusivity parameters, they require knowledge of micro- and meso-scale parameters including the foam unit cell dimensions and the bulk diffusion coefficient. Such classical approaches, however, utilize various forms of lumping which obscure the true multi-scale characteristics of the physical situation. Various alternative approaches were considered including continuum and automaton-based models which explicitly include aspects of the multi-scale microstructure and properties of the material. Experimentally measured diffusion coefficients and microstructural data was used as model inputs. Predicted foam diffusivities were compared to observed experimental behavior and to classical model predictions for various inert and light hydrocarbon molecules.