Role of additive for polycyclic compound in the suppression of electrical tree generation in LDPE

The influence of addition of polycyclic compounds into LDPE upon electrical tree initiation was investigated to demonstrate the fundamental role of the aromatic compound in the tree initiation process. Five kinds of the polycyclic compounds were used in this study; naphthalene (Np), anthracene (An), 9,10-bromoanthracene (Br-An), tetracene (Te) and pentacene (Pn). The experimental results indicated that the tree initiation voltage (TIV) depend on the kind of polycyclic compounds added to LDPE. TIV for ldquoPE/Anrdquo is the highest, and is about 3.5 times higher than that for ldquoPErdquo (without additive). TIV for ldquoPE/Br-Anrdquo is the secondly highest. However, the scatter for ldquoPE/Br-Anrdquo is much wider than that for ldquoPE/Anrdquo. TIVs for ldquoPE/Terdquo and ldquoPE/Pnrdquo are not significantly higher than that for ldquoPErdquo. The addition of ldquoNprdquo has almost no effect on the increase in TIV. The mechanisms for the increase in TIV are discussed based on the experimental results with the pi-electron effects for absorption of kinetic energy of the hot electron and observations of deposit of the additive in the test materials by AFM and SEM.