Physicochemical and electrochemical characterization of battery separator prepared by radiation induced grafting of acrylic acid onto microporous polypropylene membranes

Mutual radiation grafting technique was used to graft acrylic acid on micrometer thick micro-porous polypropylene membrane using high-energy gamma radiation.Grafting could not be achieved in aqueous acrylic acid solution.The presence of Mohr's salt effectively retarded the homopolymerization of acrylic acid but did not lead to grafting enhancement.Mohr's salt in presence of acids was found to be effective in enhancing the grafting yield.Contact angle measurement studies of the grafted and radiation treated polypropylene showed that initial grafting as well as radiation treatment of poly(propylene) in aqueous medium and in presence of Mohr's salt enhances its affinity towards the grafting solution.The enhancement in the polar component of surface energy of treated polypropylene membrane is the primary cause of grafting enhancement.The membranes grafted to an extent of ~20% were found to perform comparably with the battery separator presently being used by battery industry.