Investigation on the effect of micro and nano fillers on electrical and thermal conductivity of glass epoxy hybrid composites

The electrical and thermal properties of polymer composites are enhanced by the incorporation of nano and micron fillers. Reported work on polymer composites with the combination of micro and nano sized fillers like silicon dioxide; alumina, silicon carbide, molybdenum disulphide, and graphite are limited. In this investigation, the AC conductivity of composites with the combination of micro and nano fillers was determined over a frequency range of 20 Hz to 10 MHz, at temperatures of 25, 50 and 75±2⁰ C. The thermal conductivity of composites was also determined to investigate the synergistic effects of the hybrid fillers. The AC conductivity of the composites shows minimal dependence in the low-frequency range, and it increases at higher frequencies. Composites with hybrid fillers exhibit relatively higher AC conductivity of 10-3 S/m at 75oC. The thermal conductivity of 0.68 W/m k which is achieved with molybdenum disulphide filler, is twice the value of the base epoxy. The composites with the combination of micro and nano sized fillers also reveal good enhancement of glass transition temperature to 145oC and exhibit better electrical and thermal properties than the composites with individual micron or nano fillers.