Influence of water ageing on variation in space charge and thermo-mechanical properties of epoxy micro-nano composites

Water ageing was carried out with epoxy micro-nano composite specimen. Silica micro particles and ion trapping nano particles were used as filler material in the composite specimens. Water ageing was carried out under room temperature and at 90 degrees C, to analyse the impact of water intake on space charge accumulation and charge decay characteristics. The threshold for space charge accumulation in epoxy specimens reduces, while the rate of space charge accumulation increases after water ageing. The initial surface potential had a marginal increment and the rate of surface potential decay has reduced significantly after water absorption. Trap distribution characteristics confirm the existence of deeper traps and charge mobility reduction in case of water aged specimens. The dynamic mechanical analysis have confirmed the viscoelastic behaviour of epoxy micro-nano composite specimens, is sensitive to the water absorption. Glass transition temperature of epoxy specimen after water absorption has shifted to lower temperatures due to plasticisation of polymer matrix and ascertained with the reduction in the activation energy. Digital image correlation method has been adopted to determine strain field distribution and displacement of the specimen under mechanical loading. Thermo gravimetric Analysis have confirmed the reduction in thermal stability resulting for water aged specimens.