The effect on dielectric loss of polyethylene caused by acetophenone and cumylalcohol

The effects of acetophenone (AP) and cumylalcohol (CA) on the tanδ of low density polyethylene (LDPE) were investigated in detail taking the temperature range of 25 to 100°C and electrical stress range of 5 to 40 kV/mm. The tanδ of LDPEs to which AP and CA (reagent special grade) and these additives purified by absorbent (activated clay) have been added, was compared with the tanδ of LDPE without any additives. The analysis by dividing tanδ into the dipole factor tanδ_D and the conductive factor tanδ_c (tanδ-tanδ_D+tanδ_C) showed that the additives (AP, CA) have only very small influence on tanδ_D above room temperature. On the other hand, since the contribution of tanδ_C markedly increases in the higher temperature and higher electrical stress region depending so much on whether additives are added or not and whether the additives are purified or not, ionic carriers were estimated as carriers of tanδ _C. Two kinds of carrier source, that is to say, the carriers with small activation energy (~9 kcal/mol) and the carriers with large activation energy (~18 kcal/mol) were estimated in the tanδ_C of LDPE with additives. The former carriers (with small activation energy) could be removed by purification of additives, resulting in large reduction of tanδ_C in the high electrical stress region. However, even after the purification, the latter carriers (with large activation energy) could not be removed sufficiently, showing 2 to 3 times of the carrier concentration as much as LDPE without additives