Thermally stimulated currents (TSC) on new and field-aged underground cable material

Field-aged and unaged cable material have been investigated with the TSC technique. Two well defined relaxation modes have been observed for both materials: one high temperature peak (α) at about 115 °C that can be related to the melting of the crystalline phase of the polymer and one low temperature peak (β) located at about -300 °C that can be associated with the glass-rubber transition. Comparison between both sample spectra have shown some noticeable differences. The field-aged material exhibited: (1) lower magnitude ofthe a peak; (2) slightly higher magnitude and temperature shift towards higher temperature for the β peak; (3) higher density and (4) lower melting enthalpy