Cation Membrane By Radiation Grafting Of Halogenated Styrene Onto FEP Films

This article introduced grafted membrane prepared with tetrafluoroethylene-hexafluoropropylene copolymer by the method of preirradiation graft copolymerization and strong acid sulfonated cation-exchange membrane prepared with sulfnation. In the research, we used of styrene (St), Fluorostyrene (F-St), chloro-styrene (Cl-St) as the grafting monomer, and FEP-St grafted films were modified bromide.We explored the the grafting reaction of p-Fluorostyrene monomer, then discussed the influences of the radiation dose, grafting temperature on the grafting reaction, and got grafting reaction kinetic equation, the apparent activation energy and other parameters.By analyzing grafted membranes and sulfonated membrane with DSC-TGA, we proved that:the thermal stability of graft chain was effected by the substituent. The order of bond energy intensity:F> Cl> H; the electronegativity of Substituents also affected the acidity of the membranes. Experimental studies which using KMnO4 about the oxidation of the sulfonated membrane showed that:the electron withdrawing groups on the benzene ring affected the side chain, oxidation from small to large order is:FEP-St-SO3H< FEP-St-Br-SO3H< FEP-ClSt-SO3H< FEP-FSt-SO3H. Raman spectroscopy results showed that:the presence of electron withdrawing groups improved the bond energy of C-H in the benzene ring. Scanning electron microscopy showed that the molecular weight of grafted monomer affected the micro-structure of grafted membranes, and larger of the molecular weight, more dense of membrane structure. XRD results showed that the crystallinity of grafted membranes was lower than FEP.