The dc conductivity characteristics of barium titanate filled acrylic resin

The modification of the conductivity characteristics of polymer insulation at high electric fields through the inclusion of appropriate fillers has been the interest of many research groups in the application of stress grading materials. It has been previously found that the inclusion of barium titanate into polymers, has allowed a non linear current density with electric field characteristic to be evolved, under AC conditions. The mechanism behind this non linear characteristic is through a process of spontaneous domain alignment, within the barium titanate crystals. The electrical resistance of these composite materials is high and the AC conduction is therefore predominantly capacitive rather than resistive and the non-linear current versus field characteristic results from a field-dependent permittivity. This paper now investigates the DC conductivity characteristics of the filled resin, and attempts to suggest the conductivity mechanisms involved under DC conditions. The resin used in this investigation is an acrylic resin, with a variety of filter concentrations of barium titanate. The dependence of DC conduction on elevated temperatures is also investigated, again suggesting the mechanisms behind the results.