DC Breakdown in Polyetherimide Composites and Implication for Structural Engineering

Recent advances in nanomaterials permit the improvement of dielectric characteristics of ceramic / polymers nanocomposites. In addition, it is recognized that incorporation of nanofillers improves the mechanical, chemical, optical, acoustic, and thermal properties of polymers. Voltage endurance and electrical breakdown strength of dielectrics were even enhanced with some nanometric particles. Nevertheless, the preferred filler type and consistent improvement in the breakdown strength in the resulting nanocomposites are not well understood. In this paper, the effect of various fillers (metal, semiconductor and insulator) was studied showing the weak relationship of breakdown strength with the band gap of the nanoceramic fillers. Published data on dielectric constant and breakdown strength of various dielectrics was analyzed from the viewpoint of energy band gap. The results show that interfacial interaction of the ceramic particle-polymer appears to be very important to the electrical breakdown of the nanocomposites. An engineered nanodielectric structure is proposed for higher permittivity and dielectric breakdown strength. Lacking of control of this interface and structural order at mesoscopic level is subjected to fundamental limitations of the nanodielectric engineering.