FREE-RADICALS FORMED UPON PHOTOLYSIS AND RADIOLYSIS OF POLYMERS .1. RADICALS IN GAMMA-IRRADIATED AND UV-IRRADIATED POLYETHYLENE

A comparative ESR study of photolysis and radiolysis of polyethylene a t 77 K showed that the radical intermediates formed differ in nature. The ESR spectrum of polyethylene photoirradiated at 77 K exhibited eig ht hyperfine structure lines (Delta H = 1.8-2.2 mT) and was interprete d as the spectrum of the terminal allyl radical stabilized on photoind uced defects of the polymer chain. Photolytic degradation of an excite d carbonyl-containing fragment of the polyethylene macromolecule with formation of the terminal allyl radical and low-molecular-weight photo degradation products was represented in terms of the model of synchron ous multicenter transitions.