Study on the influencing factors of natural degradation of liquid silicone rubber used for external insulation

In recent years, liquid silicone rubber (LSR) has been widely used in the external insulation field. However, further study on the degradation mechanism and the influencing factors of liquid silicone rubber is still required. Especially when it is used in southern parts of China, of which the high temperature and humidity environment could accelerate the degradation process. It is reported that cracking and chalking phenomena were observed on the liquid silicone rubber sheath of PT and CT. In this paper, a series of ageing experiments were designed and carried out to test the performance of liquid silicone rubber when exposed to factors such as high temperature, high humidity, sun exposure and corona discharge. After the experiments, characteristics such as hardness, hydrophobicity, glossiness and mechanical properties were tested and SEM was used to study the change of micro structure. It is concluded that high temperature, high humidity and sun exposure play significant roles in the degradation of liquid silicone rubber, which could lead to the rise of hardness, loss of hydrophobicity, decrease of glossiness and surface cracking. The results also show that the change of mechanical properties of liquid silicone rubber were tiny.