UV and electron beam-induced cationic polymerization

Abstract

This paper describes the basic photochemistry which has led to the development of rapid, efficient photoinitiators for UV-induced cationic polymerizations. These polymerizations are now widely employed in UV curing processes for such applications as coatings, adhesives and printing inks. The use of photosensitizers has enabled the extension of light-induced cationic polymerizations to the visible wavelength regions as well. Electron-beam irradiation is also capable of mediating the decomposition of cationic photoinitiators. The mechanism of this reaction involves reduction of the onium salt initiator by radicals generated by e-beam induced primary bond cleavage reactions. Rapid, efficient e-beam induced polymerizations at very low doses can be achieved through the use of specially designed monomers. The use of low energy electron beam radiation for thin film applications and high energy radiation to fabricate high performance carbon fiber reinforced epoxy resin matrix composites are described.