FATIGUE-EFFECT ON FREE-RADICAL DECAY IN IRRADIATED POLYMETHYL METHACRYLATE

The influence of material fatigue on molecular motion in polymethyl me thacrylate (PMMA) was investigated by the ESR method. Free radicals se rved as molecular labels informing on changes in molecular dynamics. I t has been found that the fatigue of PMMA accelerates the decay of fre e radicals. In the course of material fatigue new degrees of freedom o f motion of polymer chains come into existence. An increase in free vo lume as well as its redistribution sets in, owing to cyclic stress of the polymer. Copyright (C) 1996 Elsevier Science Ltd