Interfacial charge behavior in nanodielectrics

In recent years, the availability and low cost of nanometric-sized filler particles have generated great interest in polymer nanocomposites for a host of applications, including electrical insulation with enhanced breakdown and voltage endurance properties. This work combines the results of several experiments to add insight to the processes taking place in the crucial polymer transition region near the particle surfaces. The relative tendency to accumulate space charge under a high DC field is investigated through pulsed electroacoustic (PEA) apparatus. DC transient (absorption) currents reveal a quasi-DC conductivity that is surprisingly high in the nanocomposite, a result that is reinforced by dielectric spectroscopy, which also indicates a reduction in the nanocomposite´s real permittivity. Thermally-stimulated currents reveal the presence of shallow traps that accompany the nanoparticle inclusions. Taken together, the results of the study indicate that the transition region is responsible for the desirable nanocomposite bulk properties which are today of interest, and help explain the difference in performance between these new materials and both unfilled resin and conventional composites composed of micron-sized fillers.