Effect of nanosecond rise time of pulse voltage on the surface charge of Epoxy/TiO2 nanocomposites

Polymeric insulating materials exposed to pulse voltage with a nanosecond rise time in pulsed power have drawn increasing attention. Surface charge accumulation and decay on the charged polymers are very important parameters related to discharge. Nanocomposite technology has been used to improve the electrical properties of polymeric insulating materials. Therefore, it must be confirmed whether the nanosecond rise time of pulse voltage on the dynamic behaviour of surface charge on polymeric nanocomposites is different from that without nanoparticles. In this paper, we attempted to clarify the effect of the rise time on the electrical properties of epoxy/TiO₂ nanocomposites focusing on surface charge accumulation and decay. Samples were prepared by dispersing nano-scale TiO₂ particles into epoxy (EX) by mixing with shear force. Corona charging tests were performed at room temperature with a relative humidity of ~40%. The charge distribution was measured by means of an electrostatic voltmeter. The results show that the rise time plays an important role in the accumulating charge as well as the charge decay rate and varies with the concentration of nanoparticles and charge polarity. It is suggested that charge dynamics are dependent upon the rise time.