Acceleratory and inhibitory effects of uniaxial tensile stress on the photo-oxidation of polyethylene: Dependence of stress, time duration and temperature

Taking stress level, time duration and aging temperature into consideration, the acceleratory and inhibitory effects of uniaxial tensile stress on the photo-oxidation of HDPE is investigated. Based on this study, we try to clarify the origin of the intricate and contradictory experimental phenomena that stress shows diverse roles in the degradation of polymer materials. The interplay between the changes in the surface morphology as well as amorphous aggregation structure and the photochemical degradation process during aging is responsible for these phenomena. More exactly, the so-called interplay includes the variation of molecular orientation and packing state in amorphous region, stress transfer efficiency, thermodynamic and kinetic aspects of photochemical reaction process.261