Investigation of microstructure, electrical behavior, and EMI shielding effectiveness of silicone rubber/carbon black/nanographite hybrid composites

In this study, electrical properties and electromagnetic interference shielding effectiveness (EMI SE) of composites based on room temperature vulcanizing silicone rubber (RTV‐SR) and hybrid conductive fillers (carbon black [CB]) and graphite nanoplate [GNP]) were studied. The role of GNP/CB ratio on developed conductive networks, electrical properties, as well as electromagnetic interference (EMI) shielding effectiveness of composites was investigated in comparison with SR/CB and SR/GNP composites. Dielectric properties of hybrid composites were controlled by the dominant filler phase. Nevertheless, all hybrid nanocomposites with a higher fraction of CB in GNP/CB hybrid systems showed a lower percolation threshold and higher EMI SE. The frequency dependency of the AC conductivity revealed tunneling conduction mechanism below the percolation threshold, while above the percolation threshold, the direct contact mechanism played the dominant role of transferring electrical current. EMI shielding measurements over X‐band frequency demonstrated absorption loss as the main mechanism for the attenuation of the incident EM wave intensity in hybrid composites. POLYM. COMPOS., 40:4056–4066, 2019.