Assessment of UV-Aging of Crosslinked Polyethylene Cable Insulation by Electrical Measurements, FTIR and DSC Analyses

In this study, the effect of UV-radiation on the structural properties of crosslinked polyethylene (XLPE) power cable insulating material was investigated as a function of aging time. XLPE specimens were exposed to UV-radiation for 200 hours using low-pressure vapor fluorescent lamps. Electrical resistivity values, influence and leakage currents, and charging and discharging currents of specimens were measured and quantified. In addition, structural changes in polyethylene chains were also evaluated with Fourier transform infrared (FTIR) analyses and high-temperature oxidation stability was correlated with the level of structural deterioration as a result of UV-aging through determination of oxidation induction time and oxidation onset temperature in differential scanning calorimetry (DSC). Experimental results showed that the electrical properties of XLPE materials were significantly affected by UV radiation and resulting structural changes can be successfully assessed with electrical measurements as a rapid, easy, and reliable tool. It was also confirmed that FTIR and DSC analyses can be used to evaluate oxidative aging level of XLPE and olefinic polymers such as polyethylene and polypropylene, polyolefin-based elastomers. This study also suggests an analytical methodology to constitute the relationship between the thermal and physical properties of polyolefins and their service life.