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.