Development of High Dielectric Constant Epoxy Composite with Nano Graphene Platelets

This paper presents the details of fabrication of epoxy graphene nanoplatelet composites with high dielectric constant. Different weight percentages of graphene nanoplatelets of 0.5, 1, 2, 3 and 5 wt.% have been incorporated in to the base epoxy and by using three roll mill, uniform dispersion of the nano filler has been achieved. The variations in dielectric constant and ac conductivity in the frequency range of 100 Hz to 10 MHz and dc voltage-current characteristics have been investigated. From the results, it is observed that the highest dielectric constant is achieved in the epoxy system used with 3 wt % of graphene nanoplatelets. Further, higher dielectric constants are observed only below 1 kHz but at higher frequencies, the dielectric constant is very much reduced. The dielectric constant is also observed to reduce at 5 wt. % of graphene below the values of 3 wt. %. The observed results are explained based on the percolation theory. The results of variations in dielectric constant of the composites are also discussed as a function of frequency at higher temperatures of 50 and 75°C. The DC voltage current characteristics of the composites is also discussed for different weight percentages of graphene.