INVESTIGATION OF RADIATION GRAFTING OF VINYL-ACETATE ONTO (TETRAFLUOROETHYLENE-PERFLUOROVINYL ETHER) COPOLYMER FILMS

A study has been made of radiation-induced grafting of vinyl acetate ( VAc) on to (tetrafluoroethylene-perfluorovinyl ether) copolymer (PFA). Effects of grafting conditions such as inhibitor and monomer concentr ations and irradiation dose on the grafting yield were investigated. I n this grafting system, ammonium ferrous sulphate (Mohr's salt) was ad ded to the monomer-solvent mixture to minimize the homopolymerization of VAc and the most suitable concentration was found to be 2.0 wt%. It was found that the dependence of the initial grafting rate on monomer concentration is of the order 1.5. The degree of grafting tends to le vel off at high irradiation doses due to the recombination of formed f ree radicals without initiating graft polymerization. Some properties of the prepared graft copolymer such as swelling behaviour, electrical conductivity, thermal and mechanical properties were also investigate d. The electrical conductivity was improved by hydrolysis of poly(viny l acetate) in the grafted chains to their respective vinyl alcohols. T he tensile properties were improved by grafting; however, the elongati on percent decreased. The DTA data showed thermal stability of such gr aft copolymers for temperatures up to 300-degrees-C, but stability dec reased at higher temperatures.