Field and temperature dependence of space charge injection in a silicone rubber

The generation of space charges in a silicone elastomer has been characterized under dc voltage as a function of the temperature using the laser induced pressure pulse (LIPP) method. The analysis of the LIPP spectra has been detailed thanks to acoustical considerations, taking into account the reflection, attenuation and dispersion of the pressure wave. Both heterocharges and homocharges have been observed depending on the field magnitude (5 to 20 x 106 V m-1), polarization duration and temperature (20, 40 or 60 0C). With temperature increasing, charges are observed at lower fields. Heterocharges appear in less stressed conditions. Then, homocharges take the place of these heterocharges. Positive homocharges are observed in lower stressed conditions than negative homocharges. Mobility of these charges has not been observed below 60 0C.