Synthesis and characterization of PVA/sPTA proton exchange membranes for fuel cell applications

Abstract

Using the casting method, proton exchange membranes PEMs for fuel cell were prepared by thermal cross-linking of polyvinyl alcohol (PVA) with sulfophthalic acid (sPTA). The membranes were prepared with different cross-linking temperatures with thickness ranged between 100 to 150 μm. The prepared membranes were characterized by different techniques such as ion exchange capacity, thermal analyses, water uptake and proton conductivity. The prepared membranes showed proton conductivity between 8.46-32.7 mS/cm. Increasing the cross-linking temperature increased the cross-linking density, resulting in an enhancement in the tensile strength and thermal stability of the prepared membranes. The membrane hole sizes were obtained using positron annihilation lifetime spectroscopy (PALS) measurements. Cross-linked PVA/sPTA membranes showed a strong correlation between the free volume hole size with the mechanical stability and methanol permeability of the membranes.