Thermal aging of polyvinyl chloride used in electrical insulation

Thermal aging tests were carried out on plasticized polyvinyl chloride samples used in high voltage cables. Aging temperatures were: 80, 100, 120 and 140degreesC. This paper presents the variations of the mechanical properties (elongation at rupture and tensile strength) versus aging time. The thermal endurance graph was studied for each property; the activation energy and the temperature index were determined. The consequences of material degradation were shown up: mass loss, shrinking and change in color. At early aging stage, the degradation is due to a plasticizer loss. At prolonged times, the degradation is attributed to a stabilizer consumption followed by a material coloration and a hydrochloric acid emission.