Synthesis and characterization of hybrid conducting composites based on polyaniline/magnetite fillers with improved microwave absorption properties

Hybrid organic/inorganic electromagnetic absorbing materials (EMAMs) based on polyaniline (PANI) and magnetite (Fe3O4) fillers dispersed in epoxy resin matrix were successfully prepared for electromagnetic applications. The effects of PANI and Fe3O4 loading on permittivity, permeability and microwave absorption properties were studied. The structure and the morphology of the elaborated composites were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Electromagnetic properties and absorbing behaviors were performed over frequency range of 12.4-18 GHz (Ku-band). The results show that synthesis parameters such as amount and particle size of PANI and used Fe3O4 affect significantly the morphology, the conductivity, and the microwave absorption properties of the final materials. It was revealed that the electromagnetic parameters were higher in hybrid PANI/magnetite/epoxy resin than in dielectric PANI/epoxy resin composites. The permittivity and the permeability parameters increased to high values with the rate of fillers in the composite and remained constant with the frequency. A minimum reflection coefficient (RC) of -42 dB was observed at 16.3 GHz with a thickness around 1 mm for composites containing 15% of PANI and 10% of Fe3O4 (epsilon' = 10) and -37.4 dB at 14.85 GHz for the composite of 15% of PANI and 25% of Fe3O4 (epsilon' = 17). However, a composite made with only 20% of PANI (epsilon' = 8.5) showed a minimum reflection coefficient of -11 dB at 18 GHz with the same thickness. The possibility to modulate the electromagnetic properties of the composite materials is of a great interest to fabricate microwave absorbing and electromagnetic shielding materials with high performances. (C) 2012 Elsevier B.V. All rights reserved.