On the nature of growth of water trees and electrical aging of cross-linked polyethylene

The nature of AC field aging of cross-linked polyethylene (XLPE) using NaCl and CuSO/sub 4/ (0.1 M) electrodes was studied with Fourier transform infrared absorption (FTIR), thermally stimulated discharge current (TSDC), and thermal transient current (TTC) measurements. FTIR measurements show that oxidation of stabilized XLPE is significantly lower than that of the unstabilized materials. No noticeable increase in bound water content in the polymer was observed as measured by IR absorbance at 3370 cm/sup -1/. Progressive enhancements of absorbance at approximately 1715 cm/sup -1/ and the TSDC peak at 70 degrees C with increasing field aging time appear to have the same origin. Thermal transient current magnitude is related to that of the integrated charge released in a TSDC thermogram.<
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