Influence of carbon black in polyethylene on space charge accumulation

In several studies regarding space charge accumulation in peroxide crosslinked polyethylene (XLPE) it is identified that the products from the crosslinking process give rise to heterocharge accumulation in a DC-field. Several ways to reduce this accumulation have been proposed. We have studied polyethylene compounds containing 1 wt% carbon black of different types. It is found that compounds containing carbon black with very large surface area have somewhat lower accumulation of space charges in samples that are not degassed. One possibility may be increased adsorption of low molecular weight species formed at the crosslinking process. Measurements show that the addition of a low amount of carbon black gives higher resistivity but lower DC breakdown strength compared to unfilled XLPE