The influence of nano-filler on space charge distribution in LDPE/silica nanocomposites

The charge transport behavior is changed when low-density polyethylene (LDPE) filled with a few percent nanometer size fillers. In this paper, LDPE and LDPE/silica nanocomposites filled with different contents of nano silica were prepared, respectively. The space charge distributions and high field conduction of all samples were investigated. After pre-stressed under an electric stress of 50 kV/mm for 1 h, samples filled with different content of nano silica were shorted, and space charge was measured. It is shown that the optimum nano silica content for the lowest high field conduction current density and minimum amount of space charge formed in nanocomposite are different. The heterocharge accumulates adjacent anode and cathode in LDPE, respectively. Three different trends are confirmed in nanocompoises when the filler content increases from 0.1 to 5 % wt. In low content from 0 to 0.1 wt%, the amount of these heterocharge reduces with the increase of fillers content. In the content from 0.5 to 2 wt%, homocharge accumulates close to anode and cathode. When the content increases to 2 wt%, the amount of homocharge reaches a maximum and then reduces with the increase of content. In addition, the amounts of mean volume density of space charge reduce after filled with nano silica in LDPE matrix and the mean attenuation rate of space charge reduces with increasing of nano silica content.