Influence of temperature and electric field strength on the space charge behavior of liquid silicone rubber with carbon black nanofillers

Abstract

In order to explore the space charge behavior of liquid silicone rubber (LSR) the pulsed electroacoustic (PEA) method has been applied. Due to the elastic nature of LSR, the PEA setup was optimized to ensure a constant contact pressure and thus a constant thickness of the LSR samples. For each sample, the temperature of the ground and the high-voltage electrode was permanently measured. The space charge behavior was investigated for neat LSR and for LSR samples with two different amounts of nanoscaled carbon black (CB). The results show in general a formation of homocharges at both electrodes. At 20 °C, the negative charge from the cathode moves towards the anode in the case of neat LSR. With increasing amount of CB, the negative charge is trapped near the cathode and the charge migration is suppressed. At higher temperature, an increasing amount of positive homocharges at the anode is observed, which is suppressed for LSR with CB nanofillers. The mean charge density between the electrodes is evaluated during polarization and depolarization measurement. The results show that the mean charge density increases with temperature and electric field strength, which is explained by the Schottky and Poole-Frenkel effect. In addition, it is observed that the mean attenuation rate during the depolarization time increases with increasing amount of CB nanofillers.