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Effect of breakdown strength and space charge distribution in polyimide/TiO2 nanohybrid films aged by corona treatment

Polyimide/TiO2 (PI/TiO2) nanohybrid films containing surface modified nano-TiO2 by employing silane coupling agent (KH550) were prepared by using in-situ dispersive polymerization process. The space charge distribution, electrical aging and other dielectric properties in both pure PI films and PI/TiO2 nanohybrid films were investigated. Space charge in the nanohybrid films was measured with pulsed electro-acoustic method (PEA). Results showed that the nano-TiO2 particles have made a prominent effect on the process of dielectric breakdown, lifetime and space charge behavior. The incorporation of nano-TiO2 increased the voltage endurance significantly. We discovered the space charge were greatly decreased and field distribution trended to uniform in the nanohybrid films with the concentrition of TiO2 was 10 wt.%. The relation of space charge distribution with the concentration of nano-TiO2 and the aging time was explored. The relative mechanism of the electrical field distributions which distorted by space charges in samples was also discussed.