Analysis of Electrical, Dielectric, and Electromagnetic Interference Shielding Behavior of Graphite Filled High Density Polyethylene Composites

Conducting polymer composites were prepared by hot compression molding of high-density polyethylene (HDPE) prelocalized with graphite (I The variation of room temperature electrical conductivity, dielectric constant, and Shore-D hardness as a function of graphite content were studied below and above percolation threshold. The percolation threshold at which insulator-conductor transition takes place is estimated to be 0.029 volume fraction of graphite. The observed increase in dielectric constant with addition of graphite also found to be percolative in nature. Above percolation threshold, the dielectric constant is found to decrease sharply with increase in frequency. Electromagnetic shielding effectiveness of HDPE/Gr composites was evaluated in the X-band frequency range. The composites were found to possess both positive and negative temperature coefficient of resistance. Reproducibility of electrical resistivity with temperature was observed only below the processing temperature. POLYM. ENG. SCI., 48:2178-2187, 2008. (C) 2008 Society of Plastics Engineers