Facile synthesis of phenolic resin sheets consisting expanded graphite/-Fe₂O₃/SiO₂ composite and its enhanced electromagnetic interference shielding properties

The paper reports the preparation of thin sheets of expanded graphite decorated with γ-Fe₂O₃ and SiO₂ by compression molding. Different formulations have been prepared to study the effect of dielectric and magnetic constituent on the electrical, magnetic and dielectric properties of multiphase composite. One of the formulations shows unprecedented microwave shielding response with absorption dominated shielding effectiveness value of 55.40 dB which strongly depends on dielectric losses and magnetic losses. The results show that the dielectric loss of the composites can be attributed to natural resonance, electron polarization relaxation, interfacial polarization and the unique layered nanostructures etc.; whereas eddy current effect mainly causes the magnetic loss. Since observed attenuation is greater than the recommended limit (30 to 40 dB) of commercial application, therefore, these are potentially applied for absorbing mobile signal interference in daily life. (author)