Abstract
Gamma irradiation has an important role in grafting of styrene and methacrylic acid with different ratios onto commercial poly(tetrafluoroethylene) films containing 0.5% silica nanoparticles. It was found that from the grafting process of this system as irradiation dose; 40 kGy, comonomer composition Sty/MAA (70/30%). The prepared membranes were sulfonated and phosphonated prior to be characterized. The synthesized graft copolymer was investigated using thermogravimetric analysis, scanning electron microscopy and X-ray diffraction. The membranes were examined with proton exchange membrane fuel cell (PEMFC) applicability using water uptake, ion exchange capacity, membrane thickness and tensile strength. Proton conductivity was evaluated, and free volume sizes were measured using positron annihilation lifetime spectroscopy (PALS). The membranes of highest grafting yield (46%) have a better fuel cell performance and are more durable (up to 450 hours) than commercial compressed Nafion 115.