The Study on the Stress and Photo-Oxidative Aging of Polyethylene Cable Sheath Under Different Processing Conditions

High-density polyethylene (HDPE) materials were processed into specimens under different processing conditions in this paper. Then specimens were aged under stress and ultraviolet (UV) light in an aging box, and the aging behaviors were studied by means of surface morphology observation, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). It was found that the aging properties of sheath materials were associated with the crystallinity of surface layer. Samples in lower extrusion temperature system and higher extrusion rate had lower surface layer crystallinity and better anti-aging properties. In addition, the stress and photo-oxidative aging mechanism were explored. There were two stages in the stress and photo-oxidative aging, which was reflected in the surface layer that crystallinity increased firstly and then decreased. This study may provide better processing conditions for cable sheath materials.