Electrical conductivity of waxes as model systems for polyethylene: Role of water

Novel experimental and theoretical studies of the electrical conductivity of high-purity dodecane, paraffin wax and low density polyethylene are reported herein. The role of the charge density, water content and phase changes in determining conductivity as the temperature increases from 25 oC to 65 oC, a temperature range relevant to applications of insulating materials, is determined. Low levels of absorbed water determine the measured conductivity for T< 50 oC and this can be explained by taking account of the charge carriers produced by the auto-ionisation of water. In comparison to commercial polyethylene and lubricating oils, the temperature dependence of the conductivity of dry n-dodecane is anomalously high.