Fabrication and Characterization of Novel Crosslinked Composite Membranes for Direct Methanol Fuel Cell Application - Part I. Poly (Vinyl Alcohol-Co-Vinyl Acetate-Co-Itaconic Acid)/Phosphotungstic Acid Based Membranes

A series of novel cross-linked Poly (vinyl alcohol-co-vinyl acetate-co-itaconic acid) (PVACO) and phosphotungstic acid (PTA) based organic-inorganic composite membranes have been prepared and characterized for direct methanol fuel cell (DMFC) applications. The characteristic properties of these crosslinked composite membranes were investigated by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Atomic Force Microscopy (AFM), methanol permeability measurement and AC impedance spectroscopy. The ionic conductivity of the membranes were investigated as a function of PTA composition, crosslinking density and temperature, were in the order of 10(-3) S/cm. The methanol permeability of PVACO/PTA composite membranes were in the order of 10(-6) cm(2)/s. The membrane with the best selectivity was found to have a conductivity of 2.3 x 10(-3) S/cm and a methanol permeability of 3.35 x 10(-6) cm(2)/s. These membranes showed an Arrhenius behavior for the variation in conductivity with temperature and their activation energies were in the range of 0.13-0.17 eV.