Effect of different curing parameters on UV aging resistance of silicone rubber

Abstract

Composite insulators are widely used in power transmission systems because of their excellent mechanical and electrical properties. However, composite insulators are prone to aging. To study the influence of curing factors (curing time, curing temperature, and curing pressure) on UV aging resistance of high temperature vulcanized silicone rubber (HTV), an orthogonal test of three factors and three levels was designed. HTV samples with nine different curing parameters were made and then aged by UV irradiation (320-400 nm) for 1000 hours. Mechanical properties (hardness, tensile strength, and tear strength) and electrical properties (volume resistivity, relative dielectric constant, and dielectric loss tangent) were measured at initial time and after 1000 h. It was found that three curing factors, especially temperature, have significant influence on initial tear strength and dielectric loss tangent. Besides, initial volume resistivity was also affected by curing temperature and the initial relative dielectric constant was mainly influenced by curing pressure. To obtain the UV aging resistance of samples, the change rates of these properties from initial time until 1000 h were analyzed. It was concluded that hardness, tensile strength, and volume resistivity of the samples made at $180 ^{\circ}\mathrm{C}$ and 10 Mpa changed the least. In addition, the change rates of tear strength and dielectric properties of silicone rubber made at $170 ^{\circ}\mathrm{C}$ and 8 Mpa were the smallest.