Understanding the impact of gamma irradiation of epoxy titania nanocomposites on surface and bulk charge characteristics

Epoxy titania nanocomposites were prepared under optimum process conditions through shear mixing of titania nanoparticles in to epoxy resin, for its potential application as insulant in nuclear power plants and space applications. The complex intrinsic nature of properties, its characteristic variation due to ageing of nanocomposite insulating material upon its continuous exposure to gamma irradiation, and their charge trap and space charge characteristics are explored. Surface potential variation studies were carried out under DC voltage. In the present study, the charge trap performance was assessed under switching impulse voltage. It is observed that surface potential decay and shallow trap formation are high with gamma irradiated specimen. In addition, the potential decay is high under switching impulse voltage compared to DC voltage. Also, the trap depth formed is less under switching impulse voltage compared to DC voltage and it is high under negative DC voltage. The space charge analysis through Pulsed electro acoustic (PEA) studies has shown increase in accumulation of space charge and enhancement of electric field with increase in dosage of gamma-irradiation. Polarity reversal tests have revealed that the electric field enhancement is high before reversal of polarity, irrespective of level of gamma irradiation dosage. The direct correlation between characteristic variation in trap depth values with the gamma irradiated specimen and its contact angle was observed.