Effects of volume and volume rheology on the solubility of gases and liquids in glassy polymers

The predictive calculation of the solubility of low molecular weight penetrants in glassy polymers (pure polymers, blends and nano-composites) can be performer based on the knowledge of polymer density, by using the results of the Non-Equilibrium Thermodynamics of Glassy Polymers. Different examples are presented for gases, vapors, liquids and gas mixtures. For swelling penetrants, in the case of bulk rheology relatively slow with respect to the diffusion process, the polymer density varies with time during sorption; consequently the concentration assigned as boundary condition as well as the chemical potential gradient inside the polymer both vary with time. That gives rise to different non-Fickian transport behaviors (anomalous diffusion, two-stage sorption,…) which can be well interpreted by using simple relationships for the polymer bulk rheology. Different examples support the conclusion.