The Influence of Cure Method on the Sol Content and Physical Structure of Crosslinked Polyethylene Insulation

A series of transmission cables insulated with crosslinked polyethylene have been studied. The cables were cured using a variety of heat transfer methods, but were all based on the same resin system. Insulation cured with steam or dry gas gave approximately constant sol fractions across the wall thickness. Cables cured using an experimental heat transfer method gave rise to a sol fraction which increased across the wall thickness as the conductor was approached. Correlations exist between sol fraction, swelling ratio, and melting data. It is suggested that a simple melting curve determination can be used to estimate both sol fraction and crosslink density for low density polyethylenes crosslinked using dicumyl peroxide.