A predictive procedure to model gas transport and intrinsic properties of rubbery polymeric membranes using equilibrium thermodynamics and free volume theory

In this study, the lattice fluid (LF) and Vrentas’s self-diffusion (VSD) model were employed to predict the gas sorption, diffusion, and permeability through various rubbery polymeric membranes, like PDMS, PB, PE, and PIP as homopolymers and SBR (36 wt.%) and EVAc (54 wt.%) as copolymers. The LF model with use of variable characteristic parameters that were based on the temperature and pressure range of interest, enabled to predict convex behavior of pressure-induced sorption of PDMS and PB with an AARD < 3%. The Dullien method was also used to calculate the self-diffusion coefficient of pure components in the selected polymers. Extending VSD model led to reliable gas diffusion predictions with AARD < 10% for all systems. Furthermore, using concept of bulk modulus in combination with Tait equation, pressure functionality of diffusion factor was successfully corrected. The pressure and temperature dependency of the gas permeability through the selected homopolymers and copolymers were also investigated by the proposed model, and it was observed that the predicted permeability values were consistent with the experimental data.