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

摘要

Hybrid organic/inorganic electromagnetic absorbing materials (EMAMs) based on polyaniline (PANI) and magnetite (Fe_3O_4) fillers dispersed in epoxy resin matrix were successfully prepared for electromagnetic applications. The effects of PANI and Fe_3O_4 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 Fe_3O_4 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 Fe_3O_4 (ε' = 10) and -37.4 dB at 14.85 GHz for the composite of 15% of PANI and 25% of Fe_3O_4 (ε' = 17). However, a composite made with only 20% of PANI (ε' = 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.