Synthesis & characterization of PVA/STA composite polymer electrolyte membranes for fuel cell application

Chemically cross-linked composite membranes consisting of poly(vinyl alcohol) (PVA) and silicotungstic acid (STA) have been prepared by solution casting and evaluated as proton-conducting polymer electrolytes. The proton conductivity of the membranes was investigated as a function of blending composition, cross-linking density, and temperature. The conductivity mechanism was investigated by using Impedance spectroscopy in the region between 40 Hz and 10 MHz. Membranes were also characterized by FTIR spectroscopy to confirm the crossl-inking reaction and differential scanning calorimetry (DSC) to assess the thermal stability. Membrane swelling decreased with increase in cross-linking density accompanied by improvement in mechanical properties. The proton conductivity of the membranes was of the order of 10(-3)S/cm and showed similar resistance to methanol permeability as Nafion 117 under the same measurement conditions.