A Study of Capillary Porous Structure and Sorption Properties of Nafion Proton‐Exchange Membranes Swollen in Water

Abstract

The standard porosimetry method (SPM) was used to study capillary porous and sorption properties of Nafion® proton‐exchange membranes. Pore volume‐size and surface‐size distributions were recorded together with water distributions as a function of capillary pressure and desorption isotherms. The measurements were performed at 20 and 80°C; only a small temperature effect was found for the porous volume structure. Using these data, the charge density at the inner pore surfaces was evaluated. The estimate suggested only a small degree of diffuseness of the proton double layer at the inner pore surface.