Preparation of Novel Corona-Resistance Polyimide/Spherical SiO2 Hybrid Films

Abstract

In this study, a novel type of corona-resistance polyimide/spherical SiO2 hybrid films based on 3,3,4,4-biphenyltetracarboxylic dianhydride (s-BPDA) and 1,3-bis (4-aminophenoxy) benzene (1,3,4-APB) was synthesized by incorporation with different loadings of spherical SiO2 particles via in-situ polymerization. All the films were prepared by a so called two-step procedure and finally cured at 300°C. TEM images showed the SiO2 particles were homogeneously dispersed in the polyimide matrix by means of ultrasonic method and the addition of coupling agent. Experimental results indicated that the hybrid films with much higher inorganic content exhibited good thermal and mechanical properties as well as low water absorption. Especially, the dielectric strength and electric aging time of the hybrid films were obviously enhanced, which was attributed to the highly dispersed spherical SiO2. The morphology changes of the film surface caused by the electric field were also studied by scanning electron microscope (SEM).