The effect of electrode materials on TSC of EPR with hard clay

We are investigating the polarization phenomena of ethylene propylene rubber (EPR) with hard clay. In this paper we have investigated the effect of electrode materials on thermally stimulated current (TSC) of EPR, and found that the TSC of EPR with evaporated gold electrodes has three peaks, P/sub 1/, P/sub 2/ and P/sub 3/ which appear around 60, 35 and 20/spl deg/C, respectively. The P/sub 1/ and P/sub 2/ peaks are reduced rapidly with decreasing the polarizing temperature Tp from 35 to 9/spl deg/C, and disappear if Tp<9/spl deg/C. While the P/sub 3/ peak is not clear at higher polarizing temperature because of the large height of the P/sub 1/ and P/sub 2/ peaks, it appears clearly if Tp<9/spl deg/C. On the other hand, the TSC of EPR with evaporated aluminum electrodes has two peaks, P/sub 2/ and P/sub 3/, when Tp<29/spl deg/C, though it has all the three peaks, P/sub 1/, P/sub 2/ and P/sub 3/, if Tp=29/spl deg/C. The P/sub 1/ peak depends on electrode materials. The P/sub 2/ and P/sub 3/ peaks for the sample with aluminum electrodes have almost the same characteristics as that with gold electrodes, being independent of electrode materials. From these results, we show that the P/sub 1/ peak is due to space charge polarization, and the P/sub 2/ and P/sub 3/ are due to interfacial polarization.