Influences of crosslink density on the performance of PVA-diphenylamine-4-sulfonic acid sodium salt composite membranes

Abstract

In the present paper, diphenylamine-4-sulfonic acid sodium salt and silica nanoparticles are introduced into poly (vinyl alcohol) (PVA) matrix to improve the thermal and mechanical properties through crosslinking with glutaraldehyde (GA) under acidic conditions. Proton conductivity, ion exchange capacity, and swelling ratio are examined as a function of the crosslinking degree. The membranes showed a degree of crosslinking between 6.1 and 33%. XRD experiments revealed that the amorphous character of the newly developed PVA membranes is improved by increasing the amount of GA. FE-SEM observations confirmed a major change of the surface morphology owing to the variation of GA content. It is also demonstrated that the proton conductivity decreased by increasing the crosslinker content and its maximum value, 6 × 10−2 (S/cm), is obtained for the membrane having 2 wt% of glutaraldehyde. Results showed that the methanol permeability decreased by increasing the concentration of GA. The prepared membrane consisting 5 wt% of silica nanoparticles showed the best thermal and mechanical properties.