Electrical and shielding properties of epoxy composites containing hybrid carbon fillers

Abstract

Abstract The electrical and shielding properties of the epoxy resin (ED20) filled with graphite nanoplatelets and cut carbon fibres were investigated. The filler content was varied within 3–15 wt%, and the weight ratio of graphite nanoplatelets and carbon fibres was equal to 9:1. The DC conductivity was investigated by the two‐ or four‐probe methods in the temperature range 77–293 K. The shielding properties were measured in the frequency range of 26.5 to 37.5 GHz. The real part of the permittivity ε′ r and the loss tangent tan δ for these composites were determined by the short‐circuited line method. The addition of carbon fibres slightly decreased the percolation threshold ( C cr ≈ 5.2 wt%) and caused a lower electrical conductivity with increasing filler content. Moreover, the addition of carbon fibres enhanced the shielding properties of composites mainly due to the increase of the electromagnetic radiation reflection index R .