Influence of nano-filler on high field threshold property in LDPE/silica nanocomposites

The high field conduction was investigated in low-density polyethylene (LDPE) and LDPE/silica nanocomposites filled with various size and concentration of nanosilica. The concentration was from 0~5.0% and the average particle size was 7 nm and 16 nm, respectively. It is found that the effect of nanofiller is not distinct for conduction at low electric field. The introduction of nanofiller at low concentration about 1.0% could not suppress the conduction at high electric field. The threshold fields are significantly lower in the nanocomposite, compared with that of pure LDPE. However, the conduction current at a high field remarkably reduces at high concentrations and the threshold fields apparently increase. The conduction current at high field is smaller in nanocomposite filled with 7 nm nanofiller, compared with that filled with 16 nm nanofiller. Moreover, the threshold fields are also lower in nanocomposite filled with smaller particle. In addition, the total trap density H evaluated from the high field conduction based on space charge limited current (SCLC) theory decreases at low nanosilica concentration and increases at high nanosilica concentration. Moreover, H increases with the increase of nanosilica concentration from 0.1% to 5.0%. It is considered that the increase of total trap density H in nanocomposite with the nanofiller concentration is caused by the increase of interface between nanofiller and LDPE matrix. © 2013 Chin. Soc. for Elec. Eng.