RADIATION-INDUCED CHANGES IN POLYMERS AND THEIR INFLUENCE ON GRAFT POLYMERIZATION

摘要

The preparation and irradiation behavior of a number of polymers, particularly those of the acrylate and methacrylate families, were studied. Particular emphasis was placed on the role of structural factors and their importance in the investigation of radiation susceptibility. It was found that polymer molecular weight influences site formation. Site concentration is quite markedly-affected by dose rate. Cyclization of the pendant-ester group has somewhat the same effect as has chain branching. Comparison of the EPR spectra of methacrylate polymers having cyclic ester groups with those having acrylic pendant structures suggests mechanistic differences associated with free-radical formation. Poly-2-kydroxypropylmethacrylate was examined in a continuation of investigations of structural effects and found to produce a type of EPR spectrum that would not be predicted from conventional structural considerations. In addition to an investigation of the mechanism of free-radical formation, postirradiation graft-copolymerization reactions were examined in some detail. Direct grafting methods as well as vapor-phase and peroxide-initiated copolymerizations were studied.