Abstract: A photoinduced concurrent radical-cationic polymerization hybrid system composed of epoxy resin 618/epoxy resin 6101/acrylate with diphenyliodonium salt as photoinitiator was studied. Under UV irradiation the radical and cationic polymerization was carried out simultaneously. The rate constants of radical and cationic photopolymerization of acrylate and epoxy components were determined by infrared spcctrometry, gelatinfraction and hardness respectively. The results obtained show that the acrylate is more reactive related to epoxy component. Evidently the rate of photocuring increases with increasing degree of epoxy content. Such hybrid systems may provide greatly flexibility in formulating UV-curable compositions toward the goal of achieving desirable properties and application.

Key words: radical/cationic photopolymerization, diphenyliodonium salt