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The gas and vapor transport into films of Hyflon† Ion H, a short-side-chain perfluorosulfonic acid ionomeric (PFSI) membrane, suitable for use in proton exchange membrane fuel cells (PEMFC), has been studied at various temperatures (358C, 508C, and 658C). The permeability and diffusivity values of He, N2, and O2 show an Arrhenius type dependence on temperature in the range inspected. Pure water vapor permeation was studied at 658C, at low/medium activity values. The determination of water transport parameters has been performed by solving numerically the water mass balance with a variable diffusion coefficient and accounting for a water immobilization reaction onto the hydrophilic sites of the matrix. The boundary conditions vary in time according to the mass balance on the penetrant volume. The solution allows to represent closely the experimental permeation behavior in all its stages.

The permeability and diffusivity of N2, O2, and He in a Hyflon† Ion membrane were characterized at 358C, 508C, and 658C, respectively. The data show good reproducibility and lie on an Arrhenius plot; the permeability follows the order P(He) > P(O2) > P(N2), as well as diffusivity. The water permeation was characterized at 658C: the permeability, obtained from the steady state behavior, increases with activity from 2 )102 to 13.3 )103 Barrer. The variation of diffusivity with concentration, as well as the simultaneous presence of the reaction of water immobilization onto the hydrophilic sites were taken into account, allowing to describe the entire permeation curves under different conditions.