Study of the Effects of Fluorescence UV Radiation and Low Temperature on PVC Cable Outer Sheaths

Underground Polyvinylchloride (PVC) sheath power cables are exposed to the atmospheric condition during installation. Depending on the atmospheric conditions the cable sheath is facing extreme environmental stresses such as ambient temperature (high and low), direct sunlight (UV) radiation, rain or water accumulation etc. The life of PVC cables is reduced by being exposed to harsh environmental conditions and can subsequently damage the unprotected cables. This work is aimed to the study of the effects of UV radiation and low temperature on PVC cable outer sheaths. Three commercially available PVC cable were chosen for the study. UV exposed PVC insulations become brittle after UV exposure and in low temperature. UV exposure eventually results in material degradation, diminishing the performance characteristics of the material. Thermogravimetric Analysis (TGA) was used to characterize the thermal behavior of PVC cable insulation materials before and after UV ageing. In addition, Fourier-transform infrared spectroscopy (FTIR) was used to reveal the chemical processes that caused the UV degradation of the sample. A good agreement between results of the methods was found. Exposure to low temperature resulted in a reduction in stiffness of the polymeric structure caused embrittlement which transformed the PVC structure from a flexible material capable of undergoing large strain elastic behaviour to a stiffer material with higher yield behaviour.