Abstract
Gamma radiation-induced graft copolymerization of styrene monomer on a polyvinyl alcohol film has successfully prepared a proton exchange membrane based on polyvinyl alcohol/silicon nanoparticles (PVA/SiO2), for use in fuel cells. The physical and chemical properties of the prepared hybrid nanocomposite membranes were examined by the Fourier transformer infrared spectrometer (FTIR) and the hardness test. The electrochemical properties were studied as a function of the degree of grafting at different doses of gamma irradiation. Ion exchange capacity (IEC) was found to improve with rising in the degree of grafting and then slightly decrease because of styrene homo-polymerizes as the dose of gamma irradiation intensifies. As the graft grade increases, the proton's conductivity rises to 30% of the degree of grafting and then begins to stabilize. The free volume hole size obtained from positron annihilation lifetime (PAL) experiments was found to increase by the further accumulation of the styrene graft content. The results of PAL support electrochemical results. Also, a strong link between the results of nanoscopic properties from PAL, and the results of chemical and physical properties (macroscopic results) has been successfully established. The prepared PVA/SiO2-grafted sulfonated styrene seems to be a potential alternative to Nafion for fuel cell applications.