Nanostructure analysis and dielectric properties of PVA/sPTA proton exchange membrane for fuel cell applications: Positron lifetime study

Proton exchange membranes made of cross-linked polyvinyl alcohol and sulfophthalic acid (PVA-sPTA) were successfully fabricated by casting method and crosslinked at 100 °C with sPTA concentrations ranging from 10 to 30 wt%. TGA studies proved that the thermal stability of the crosslinked membranes was enhanced with increasing sPTA content. A Conventional fast–fast coincidence spectrometer was used to measure the RT positron annihilation lifetime parameters as a function of temperature. Proton conductivity was studied as a function of temperature and frequency. Ortho-positronium lifetime o-Ps, τ3 and the intensity I3 were found to decrease with increasing sPTA content as well. The glass transition temperature, determined from the positron annihilation lifetime temperature studies, was increased with increasing sPTA content. ε/ and ε// were increased with sPTA content. The binding energy of the charge carriers Wm decreased with increasing temperature which points out that the predominant conduction mechanism is the correlated barrier hopping. •Positron annihilation lifetime spectroscopy to monitor nanostructure variations within PVA/sPTA proton exchange membrane.•The role Inhibition effect of sPTA on free volume properties of PVA.•Reported of Free volume dielectric correlation of PVA/sPTA proton exchange membrane.