Polyethylene/Dibenzylidene Sorbitol: effect of composition on space charge of polymeric insulation systems

This paper examines the effects of 1,3:2,4-dibenzylidene sorbitol (DBS), a low-molecular organic molecule, on the space charge distribution in polyethylene. Morphological studies of the blends show the presence of a DBS network in the host system. Avrami analysis shows an increase in the nucleation density of polyethylene with the nucleating agent. Accumulation of space charge is one of the main causes of failure for high voltage cables and it depends on many factors such as additives, materials and treatment. In the present study we investigate the effects of different quantities of DBS in a blend of polyethylene. The space charge response during a stressing period and decay after removal of the applied electric field were observed. The results show that space charge accumulations are dependent on the concentration of the nucleating agent. In particular, the decay in a sample with 0.3 % DBS indicates shallow traps, whilst samples containing 1 and 3 % DBS show evidence of deep trap charges.