Phenolic resin-based composite sheets filled with mixtures of reduced graphene oxide, γ-Fe2O3 and carbon fibers for excellent electromagnetic interference shielding in the X-band

Composite sheets consisting of phenolic resin filled with a mixture of reduced graphene oxide (RGO), gamma-Fe2O3 and carbon fibers have been produced by compression molding. Its electrical conductivity lies in the range 0.48-171.21 S/cm. Transmission and scanning electron microscopy observations confirm the presence of nano particles of gamma-Fe2O3 (similar to 9.8 nm) and carbon fiber (similar to 1 mm) which gives flexural strength to composite sheets. Thermogravimetric analysis show that the thermal stability of the sheets depend upon the amount of RGO and phenol resin in the composite. Complex parameters, i.e., permittivity (epsilon* = epsilon' - i epsilon '') and permeability (mu* = mu' - i mu '') of RGO/gamma-Fe2O3/carbon fiber have been calculated from experimental scattering parameters (S-11 and S-21) using theoretical calculations given in Nicholson-Ross and Weir algorithms. The microwave absorption properties of the sheets have been studied in the 8.2-12.4 GHz (X-Band) frequency range. The maximum shielding effectiveness observed is 45.26 dB, which strongly depends on dielectric loss and volume fraction of gamma-Fe2O3 in RGO matrix. (c) 2012 Elsevier Ltd. All rights reserved.