Grafting of Styrene onto Commercial PTFE Membrane and Sulfonation for Possible Use in Fuel Cell

Abstract

Commercial poly tetrafluoroethylene (PTFE) inserted in silica with ratio of 8% was chosen. Gamma irradiation was used for grafting of different ratios of styrene onto membrane in one and / or two steps. Monomers mixture of styrene and each of methacrylic acid or acrylic acid were used as binary monomers for grafting of such membrane to raise the grafting percent and aids proton conductivity. Sulfonation of the grafted membrane was performed for hydrogen proton conduction enhancement. Confirmations of the grafting and sulfonation have been achieved by FTIR investigation while Ion exchange capacity was studied as well. The mechanical properties of the grafted PTFE were tested by hardness tester while their thermal behaviors were investigated using thermal gravimetric analysis. It was found that maximum water uptake percent of the sulfonated membrane reached to 28% by weight. The proton conductivity of the prepared membranes were measured by AC impedance spectroscopic analysis, it was reached to 9.6 x 10-3 Ohm-1 Cm-1 which is comparable to that of Nafion.