Effects of calcium carbonate filler on the hydrophobic property of XLPE

The aging of cross-linked polyethylene (XLPE) when exposed to surface discharges in the presence of contamination produced in salt-fog is associated with the loss of the hydrophobicity on the surface. The loss of hydrophobic surface is accelerated by the high temperature generated by dry band arcing in wet and contaminated conditions. To investigate the process of wettability of the surface and its dependence on the level of calcium carbonate (CaCO₃) filler, XLPE specimens were also immersed in saline water solutions at various levels of salinity from 5.5 to 1000 μS/cm and various temperatures from 27 to 92.5°C and energized with electric stress of 0.58 kV_rms/cm in a salt-fog chamber. Measurements of the contact angle and surface roughness were used to categorize the state of the surface. Mechanisms responsible for the observed phenomena are suggested