Radiation Reactions of Unsaturated Polyesters

Abstract

The polymerization of monomers containing more than one double bond may lead to the formation of crosslinked polymers. The monomers involved in this work were unsaturated polyesters. Ionizing radiation was found to initiate polymerization and, at the same time, lead to an insoluble network by causing crosslinking between the polyester chains. The effect of both low- and high-intensity radiation, additives, oxygen and temperature has been studied and it is shown that the polymerization proceeds via a free-radical chain mechanism, although the poly-addition chain lengths produced seem to be very short. The absence of any dependence of the conversion on the radiation intensity suggests an unusual chain-termination step. An analysis of the results shows that neither the structure of the polyester nor its type of molecular weight distribution is of major importance in affecting the general course of the polymerization.