Grafting of styrene-acrylic acid (sty-AA) polymer onto fluorinated ethylene propylene copolymer (FEP) was carried out by preirradiation of FEP with gamma-rays. Effect of reaction conditions on the degree of grafting such as total radiation dose, monomer concentration, temperature, and time of grafting has been studied. From the study, it is seen that the degree of grafting is strongly dependent on the reaction conditions. The rate dependence of 0.53 (similar to0.5) and 1.03 (similar to1) have been obtained with respect to total dose and monomer concentration, respectively indicating that radiation induced grafting follows free radical polymerization. The activation energy for the grafting in the temperature range of 60-90degreesC is found to be 33 kJ/mol. The results indicate that the grafting takes place by the front mechanism where the grafting starts at surface and slowly proceeds inwards by diffusion of the monomer through the swollen grafted chains. (C) 2003 Wiley Periodicals, Inc.