Effect of Silane Coupling Agent Modified Alumina Filler on Breakdown Characteristics of Epoxy Composites

Alumina is an important part of epoxy composites, filling into epoxy resin, improves the mechanical strength of epoxy composites, but reduces the electrical properties of epoxy cured products. In order to solve this problem, used silane coupling agent modified alumina filler, and prepared test sample. Used the voltage breakdown tester measured the breakdown strength of the sample, the pressurization speed is 2000 V/s. The results show that with the increase of alumina filling, breakdown strength of the sample was decreased. The sample prepared by using γ-aminopropyl triethoxysilane modified alumina filler, with the increase of the amount of γ-aminopropyl triethoxysilane, the breakdown strength increased first and then decreased, and when the amount of γ-aminopropyl triethoxysilane is 1.5 wt% of the alumina filler, the breakdown strength is the largest, maximum is 35.5 kV/mm. The addition of a silane coupling agent to the neat epoxy resin reduced the breakdown strength of the sample, but to a lesser extent.