Effect Of Gamma Irradiation On Electrical Properties Of Epoxy Based Nanocomposites

In recent years,with the rapid development of nuclear power,polymer insulation materials have been widely used owing to their superior electrical and mechanical properties.But in these radiation environments,the polymer materials are inevitably affected by high energy radiation such as gamma rays.Owing to its excellent insulation properties,polymer based nanocomposites show wide application prospects in the field of nuclear power,and also its ageing mechanism in radiation environment is of great concern.In this paper,the epoxy/alumina?EP/Al₂O₃?nanocomposites dielectric which was doped with different content of nano-?-Al₂O₃ particles,then irradiated by⁶⁰Co gamma ray irradiation source.The effects of gamma irradiation dose on the electrical properties of nanocomposites materials were analyzed by combining the characteristics of trap distribution,charge transport and the ability of partial discharge resistance.The main work are as follows:1.The bisphenol A epoxy resin?Epoxy,EP?,LMW polyamide and nano-?-Al₂O₃with average particle diameter of 60 nm treated by titanate coupling agent were mixed uniformly by means of physical blending to cast EP/Al₂O₃ samples with different loading of 0 wt%,1 wt%,3 wt%,5 wt%.The samples were irradiated by ⁶⁰Co gamma ray irradiation source.The total irradiation dose were 0 kGy,100 kGy,500 kGy,1000kGy respectively.Dielectric constant and DSC were applied to analyse the molecular physical and chemical structure.The results showed that with the total irradiation dose of gamma ray increasing from 0 to 1000 kGy,T_g increased gradually,which means the crosslinking density of nanocomposite gradually increased and the network structure of EP/Al₂O₃ nanocomposites were gradually enhanced.2.By injecting charges into the surface of the material with different polar of high voltage DC corona,the surface potential decay curve of the sample was recorded.The trap energy distribution and charge transport characteristics were obtained.The results indicated that with the increase of the total dose from 0 kGy to 1000 kGy,the trap energy depth exhibited a rising-then-falling trend while the carrier mobility showed a falling-then-rising one;with the increase of the addition of nano-sized fillers from 0 wt%to 5 wt%,the trap energy depth and the carrier mobility exhibited the same trend as the total dose did.3.The property of partial discharge resistance of EP/Al₂O₃ samples was tested by the rod-plate electrode system.The influence of the content of alumina particles and the radiation of gamma irradiation on the partial discharge resistance of the samples were evaluated by means of the maximum erosion depth and the average surface roughness obtained by 3D Contourgraph.The results showed that the resistance to partial discharge of the samples was increased then decreased with the increase of the total irradiation dose from 0 kGy to 1000 kGy.The increase of the content of nano-particles from 0 wt%to 5 wt%also showed a rising-then-falling performance of partial discharge resistance.