Radiation initiated grafting onto fluoro polymers for membrane preparation II

Abstract

A study has been made for the preparation of membranes by the post radiation grafting of acrylamide (AAm) onto poly(tetrafluoroethylene) (PTFE), films. The appropriate reaction conditions were selected under which the graft polymerization was carried out successfully. In this grafting system ammonium ferrous sulphate (Mohr's salt) was used as inhibitor to minimize the homopolymerization of AAm and a suitable concentration of the inhibitor to be added to the reaction medium was found to be 0.05 wt%. The effect of monomer concentration, radiation intensity and temperature on the rate and final degree of grafting was investigated. Increasing grafting temperature rises the initial grafting rate, whereas the final grafting yield increases with temperature up to 45°C, and then declines. This behaviour was described by the influence of glass transition on the rate of termination in the semicrystalline polymer. The overall activation energy for this grafting system was found to be 14.6 and 44.5 kcal/mol above and below 35°C, respectively. Some selected properties of the graft copolymer were studied. It was found that the grafted membranes possess good mechanical and electrical properties and excellent chemical and thermal stability which makes them very promising in practical applications.