Hygrothermal ageing performance of high temperature vulcanised silicone rubber and its degradation mechanism

Abstract

Abstract High temperature vulcanised silicone rubber (SR) has excellent hydrophobicity and thus is widely applied both in indoor and outdoor insulation. According to the analysis of different experimental ageing tests and field investigation of SR, temperature and humidity are considered to be the fundamental factors during degradation. Hygrothermal ageing was proposed in this study to simulate the chalking state of the SR, finally leading to the irreversible degradation far below the thermal decomposition temperature. The variation of morphology, hardness and polydimethylsiloxane (PDMS) content was quantified during the yearlong hygrothermal ageing test. It is implied that the gradual process of whitening and hardening are accompanied by the decline of the PDMS content. Finally, ageing delamination in SR and its degradation mechanism were proposed.