Dielectric spectroscopy analysis of electrically aged low density polyethylene

The analysis of the low frequency dielectric loss of electrically aged LDPE shows an increase with electrical ageing. This could be further verified by extending the frequency range down to 10-5 Hz in order to measure the changes at the expected peak maximum. TSDC results are however inconclusive whether the measured current is due to dipoles or space charge. The observed difference between charge release from the two samples surfaces indicates that there is an asymmetrical distribution of space charge or polarization. This agrees with the optical microscope observations showing that one of the sides has a greater water tree density than the other. A difference on the initial TSDC current level (near 20°C) appears to be more dependent on the short-circuit time than on the poling time. If a TSDC is performed without poling the measured current is near zero, revealing that space charges have been removed or that the dipoles have been disoriented