Radiation grafting — state-of-the-art

Abstract

Radiation grafting is now a process more than 35 years old. In spite of an enermous amount of ingenious research, it has still not led to any large scale commercial exploitation. The same could be said, however, about the various chemical methods of graft copolymerization. Hopeful signs are beginning to appear and some of these possibilities will be discussed. The successful development of new applications of graft copolymers will be the clue to how the whole field develops. Three standard methods of grafting were developed early in the field and are still the main techniques available. These are the mutual (simulataneous), the preirradiation (consecutive), and the peroxide methods. The present status of each and the more modern developments and variations will be discussed in some detail. Although the kinetics of graft copolymerization point towards the lower dose rate gamma radiation sources, there are interesting possibilities with the use of electron beam processing. There is considerable interest, for example, in surface modification with grafting. In this respect, photo-grafting will complete with electron beam processing as it does with radiation curing. Methods of increasing the radiation yields and reducing the formation of homopolymer will also be emphasized. In the past several years, with all methods of grafting including radiation, there has been increased emphasis on applications. This may be regarded as a healthy sign in this fascinating technique.