Effect of thermochemical treatment on conductivity and mechanism of current flow in MK-40 sulfocationite membrane

Abstract

The effect of thermal treatment on the conductivity, diffusion permeability, and structure of MK-40 sulfocationite membrane is studied in the neutral, alkaline, and acidic media. Based on the experimental concentration dependences of membrane conductivity, within the extended three-wire model of conduction, the fractions of current passing through different conduction channels of membrane and the structural parameters, which characterize the volume fractions of conducting phases and their mutual orientation against the electric current, are calculated. It is found that the thermal treatment changes the mechanism of current flow in the membrane due to the reorganization of transport channels structure leading to a considerable increase in the moisture content due to an increase in the polymer macroporosity. The information on the variation of structure of transport channels in the membrane after the thermochemical treatment was obtained by the analysis of model parameters and supported by the data of independent study of its diffusion permeability and the morphology of surface and cross-section of swollen samples by the method of scanning electron microscopy.