DC current in nanosilica-based polyethylene nanocomposites

In the present paper, DC current of polyethylene nanocomposites containing different nanosilica loading ratios, either the untreated or the surface treated using the trimethoxy(propyl)silane coupling agent has been investigated. TGA was used to identify the true loading concentration in the samples and the nanofillers dispersion was studied using SEM. A range of electric field from 10 kV/mm to 50 kV/mm were applied It has been found that two dynamic processes are involved in the current observed over a period of 3 hours. The initial process was dominated by trap filling where a decreasing current versus time was observed. The second process was related to the transient space charge limited current in the unfilled sample but taken over by the effect of nanofillers that shows a continuous current increase versus time rather than peaking. The exact mechanism responsible for the increasing current is not known yet. The influence of surface treatment of the nanofillers on the current is significant, resulting in a lower current comparing with the untreated samples. A current dip has been observed for samples with lower loading concentration, supporting the deep trap concept.