Synergistic Conductivity and Electromagnetic Interference Shielding Effectiveness of Epoxy/Carbon Fiber and Epoxy/Carbon Black Composites via Mixing with Bamboo Charcoal

This study was aimed at preparing electromagnetic interference ( EMI) shielding materials based on carbon black ( CB), carbon fiber ( CF), bamboo charcoal ( BC), and epoxy resin. The effects of adding bamboo charcoal on the mechanical properties and electrical resistivity of epoxy composites were studied. Scanning electron microscopic ( SEM) analysis, electrical resistivity, and electromagnetic interference ( EMI) shielding effectiveness were also investigated. The composites were prepared at 120 degrees C by the curing-molding method through blending the fillers in epoxy resin. The results revealed that the BC/CB and BC/CF composites had perfect conductive network structure and resulted in better dynamic thermal mechanical properties. The electrical resistivity declined with the increase of bamboo charcoal contents; consequently, the EMI shielding effectiveness improved gradually. The lowest electrical resistivity, down to 0.071 Omega.m, corresponded to the best EMI shielding effectiveness of BC/CF composites, which could be above 60 dB over a frequency range of 30 MHz to 1500 MHz while the carbon fiber content was at 40 wt.%.