Radiation-induced grafting of styrene onto poly(tetrafluoroethylene) films. Part II. Properties of the grafted and sulfonated membranes

The physical and chemical properties of polystyrene grafted and sulfonated polytetrafluoroethylene (PTFE-graft-PSSA) membranes prepared by radiation-i nduced grafting of styrene onto commercial PTFE films using simultaneous ir radiation technique followed by a sulfonation reaction are evaluated. The i nvestigated properties include water uptake, ion exchange capacity, hydrati on number and ionic conductivity. All properties are correlated with the am ount of grafted polystyrene (degree of grafting). The thermal stability of the membrane evaluated by thermal gravimetric analysis (TGA) is compared wi th that of original and grafted PTFE films. The membrane surface structural properties are analysed by electron spectroscopy for chemical analysis (ES CA). Membranes having degrees of grafting of 18 % and above show a good com bination of physical and chemical properties that allow them to be proposed for use as proton conducting membranes,provided that they have sufficient chemical and mechanical stability. (C) 2000 Society of Chemical Industry.