Abstract
Study on the correlation between the tracking resistances of outdoor polymer insulating materials and environmental stresses regarding the ambient outdoor conditions has been progressing. In this study, the tracking resistance variation of a cycloaliphatic epoxy resin filled with high concentration of silica powder due to thermal ageing and water absorption is investigated. Experimental works show that the tracking resistance of this epoxy system is considerably decreased by thermal ageing and water absorption. The decrease due to water absorption is found to be an apparent phenomenon because the completely drying treatment makes the tracking resistance recover to the initial. Furthermore, it is found that the multiple effect of thermal ageing and water absorption makes the tracking resistance decrease more considerably than the case that each stress works. In addition, the tracking resistance of the thermally aged epoxy system after water absorption-drying treatment can not recover to the initial one before water absorption. Mechanisms of the tracking resistance variations of this epoxy system resulting from thermal ageing and water absorption are discussed in this paper.
