LMW components in silicone rubbers and epoxy resins

The basic loss and recovery mechanisms of composite insulator hydrophobicity are described. Two typical silicone systems, room temperature vulcanizing silicone rubber (RTV) and liquid silicone rubber (LSR) used for high voltage sheds are analysed concerning their LMW contents and quality. The hydrophobicity transfer of virgin and extracted silicones as well as the recovery after corona are described for both materials. Correlations between recovery behaviour and differences in LMWs are discussed. Standard epoxy resins with different modifications of their bulk are presented, Results from transfer experiments demonstrate that multiple transfer is possible.