Mechanism of gas permeation through glassy polymer films

Abstract

The observed pressure dependence of the mean permeability coefficients of carbon dioxide and methane in glassy polymer films such as polycarbonate, Kapton® polyimide and polysulfone, taken from existing papers, was compared with the predictions in terms of a dual-mode mobility model and a modified mobility model in which both the Henry's Law and Langmuir populations execute four kinds of diffusive movement. The pressure dependence is simulated better by the modified model than by the original model. The mean permeability coefficients and sorption isotherms for carbon dioxide and methane in commercially available polysulfone films were measured at four temperature levels between 30 and 45°C and at gas pressures up to 33 atm and 61 atm, respectively. The pressure dependence of the mean permeability coefficients for the above systems is also described well by the modified mobility model, whereas the sorption isotherms are described well by the dual-mode sorption model.