Synthesis, dielectric, and microwave absorption properties of flake carbonyl iron particles coated with nanostructure polymer

Flake carbonyl iron particles (FCIPs) coated with nanostructure polymer (meth-acrylic acid-polystyrene, MAA-PS) were synthesized by dispersion polymerization using poly (vinylpyrrolidone) as stabilizer and 2, 2-azobis (isobutyronirile) as a catalytic agent. Field emission scanning electron microscope equipped with energy dispersive x-ray spectroscopy and high-resolution transmission electron microscope was used to observe its morphology of FCIPs-MAA-PS, and thermo-gravimetric analyses were employed to characterize its mass loss of polymer surface modification. Electromagnetic properties of FCIPs before and after coating were investigated by Agilent 8720ET vector network analyzer within 0.5-18GHz. After coated with nanostructure polymer, the real part of permittivity for FCIPs/wax composite was decreased while its permeability remained nearly unchanged. Dielectric behaviors were discussed by the Cole-Cole dispersion formula. After surface modification with nanostructure polymer, reflection loss of FCIPs-MAA-PS/wax composite presented a wide absorption band and showed the minimum value of reflection loss reaching -39.4dB when the thickness was 2.50mm. Copyright (c) 2013 John Wiley & Sons, Ltd.