Gamma radiation-induced graft copolymerization of styrene onto polyethyleneterephthalate films: application in fuel cell technology as a proton exchange membrane

Polyethyleneterephthalate (PET) based proton exchange membrane for using in fuel cells was successfully prepared by gamma radiation-induced graft copolymerization of styrene monomer onto PET film and the consequent selective sulfonation of the grafting chain in the film state using chlorosulfonic acid (ClSO3H). The effects of grafting conditions (e.g., monomer concentration, irradiation dose) on the degree of grafting and sulfonation condition (e.g., optimum concentration of ClSO3H) on the degree of sulfonation were studied. The degree of grafting, the degree of sulfonation and the physico-chemical properties (such as, water uptake, mechanical strength, thermal durability, hydrolytic stability, oxidative stability) of the gamma radiation-induced grafted membrane were found to be better when compared to those of the UV-radiation grafted membrane. The membrane shows higher ion exchange capacity (0.9 mmol g−1) and higher proton conductivity (0.075 S cm−1), similar to those of Nafion membrane.