Electrical Conductivity and Electromagnetic Interference Shielding Effectiveness of Elastomer Composites: Comparative Study with Various Filler Systems

This work presents a comparison study of Electrical conductivity and Electromagnetic Interference (EMI) shielding effectiveness (SE) of three different Polydimethylsiloxane (PDMS) composites with randomly embedded Multiwall carbon nanotubes (MWCNTs), Carbon coated iron nanoparticles (FeNPs) and Graphite. The incorporation of these fillers was found to appreciably enhance the electrical conductivity and EMI shielding performance of the composites. The analysis indicated that incorporation of fillers with high aspect ratio gives increased number of conducting pathways, which in turn improved the electrical conductivity and EMI shielding effectiveness of the composites. The 1 wt% MWCNT/PDMS composite displayed electrical conductivity nearly 4 orders of magnitude greater than that of pure PDMS. These composite structures are found to provide numerous interfaces to attenuate the electromagnetic waves, giving rise to an improved shielding mechanism. This work indicates that, creating conductive links within polymer composite structures is a favorable approach to create high-performance EMI shielding materials. The electrical conductivity above 10-6 S/m for all the composites reported here makes them suitable for antistatic coating applications. SEM, X-ray diffraction and Raman spec-troscopy were used to analyze the effect of fillers on the PDMS composite structures. The higher filler content composites exhibited an EMI SE level of 20 dB necessary for commercial applications when the films were 1.5 mm thick.