Space charge dynamics in silica-based polyethylene nanocomposites

Nanodielectrics have been investigated recently as they have shown some improved dielectric properties that are important for high voltage insulation applications. One of these improvements is the reduction in space charge when the nanocomposites are subjected to high dc electric fields. It has been widely reported that the inclusion of nanoparticles in polyethylene can suppress the formation of space charge in the material. However, the detailed mechanisms that are responsible for the charge suppression are not known. In the present paper, charge dynamics in nanosilica based polyethylene nanocomposites have been observed using the pulsed electroacoustic technique. A range of electric fields have been applied to the nanocomposites with different nanosilica loading ratios to investigate the impact of the applied electric field on charge suppression. In addition the effect of surface treatment of nanosilica particles on charge dynamics has also been studied by comparing treated and untreated nanocomposites with the same loading ratio of nanosilica particles. The influence of charge dynamics, especially at higher applied electric fields, on electric breakdown of these nanocomposites has been discussed.