Attenuation of electromagnetic radiation by graphite-epoxy composites

This work presents the results of investigations of the electromagnetic shielding efficiency of composite materials (CMs) based on epoxy resin and thermoexfoliated graphite (TEG). The measurements were performed in the wide region of electromagnetic radiation (EMR) frequency from 25.5 to 77.5 GHz. It was shown that structure and morphology of the graphite fillers influence the efficiency of electromagnetic shielding. For example, the composites with nanodispersed TEG (0.56-5.9 vol%) are characterized by low value of transmission coefficient alpha(tr) in comparison with composites with TEG or TEG2 ( TEG subjected to repeated oxidation and thermoexfoliation): alpha(tr) is equal to (-29) dB for CM 10wt%TEG2+epoxy ( at the specimen's thickness h=0.6 mm). The real part of permittivity epsilon' has been determined for the epoxy CMs with nanoTEG as filler. It also was found that electromagnetic shielding efficiency slightly increases at increasing of EMR frequency. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim