Improving the surface insulating performance of epoxy resin/Al2O3composite materials by extending chain of liquid epoxy resin with Me-THPA

Abstract

Basin-type insulators are made by epoxy resin composite materials. Curing defects are easily formed in basin-type insulators, and degrade their insulating performances. High curing exothermic rates of epoxy resin composite materials have deemed as the main cause of curing defects formation. In this study, methyl tetrahydrophthalic anhydride (Me-THPA) was used to extend the molecular chain of liquid epoxy resin to prepare epoxy resin composite materials with low curing exothermic rates. Curing exothermic properties, molecular weight distribution, curing stress, microstructures, and surface flashover characteristics of the composite materials were investigated. The results showed that chain-extended epoxy resin had low curing exothermic rates. The curing stress of the chain-extended epoxy resin composite materials was small. The curing defects forming in the composite materials were inhibited. Negative DC surface flashover characteristics of these composite materials were improved. Furthermore, variation of functional groups of the composite materials was studied before and after surface flashover tests. Results showed that the content of carbon-oxygen single bonds (-C-O) in the chain-extended epoxy resin composite materials was observed to decrease. The -C-O bonds also affect the voltage withstand capability of the epoxy resin composite materials.