Xie Qiang

Silicone rubber has better gas and water permeability than other organic elastomers owning to its microporosity structure, which makes it permeable and leads to unstable internal dielectric property. Silicone rubber is a mixture of polyorganosiloxane and inorganic fillers such as silica and aluminium hydroxide. These fillers are hydrophilic and easy to absorb water, thus leading to the destruction of interface between polyorganosiloxane and filler and performance degradation. Under non-energized conditions, permeability of silicone rubber is only related to superficial area, time, air pressure as well as the free volume and filler composition. In this paper, the influences of water on silicone rubber is analysed and results show that the water permeation process and water absorption have obvious influences on the operation performance of RTV silicone rubber. It is also concluded that a precise criteria and test procedures should be specified for RTV coatings to be used in high humidity areas.