CATION-EXCHANGE MEMBRANES BY PREIRRADATION GRAFTING OF STYRENE INTO FEP FILMS .1. INFLUENCE OF SYNTHESIS CONDITIONS

Gamma radiation-induced grafting of styrene into FEP films was investi gated by the preirradiation method. The degree of grafting was found t o be strongly dependent on the synthesis conditions, such as radiation dose, monomer concentration, crosslinker, temperature, and film thick ness. The order of dependence of the rate of grafting on pre-irradiati on dose and monomer concentration was found to be 0.64 and 1.90, respe ctively. The activation energy for the grafting in the temperature ran ge of 50-80-degrees-C was determined to be 27.9 kJ/mol. A negative fir st-order dependence of grafting on film thickness was observed. The re sults suggest that the initial grafting takes place at the film surfac e and proceeds to the middle by progressive diffusion of monomer throu gh the polystyrene grafted layers. (C) 1994 John Wiley & Sons, Inc.