Microwave absorption properties of NiCoFe2O4-graphite embedded poly(o-phenetidine) nanocomposites

Poly(o-phenetidine) nanocomposites (PNG) with NiCoFe2O4 and exfoliated graphite have been synthesized via in-situ emulsion polymerization. Systematic investigations reveal that the NiCoFe2O4 nanoparticles (30-40 nm) in the poly(o-phenetidine) matrix have phenomenal effect in determining the electrical, magnetic, and the microwave absorption properties of the nanocomposites. Shielding effectiveness due to absorption (SEA) value of 32 dB (>99.9%) has been achieved for PNG composite for its use as broadband microwave absorbing material. The microwave absorption of these composites can be attributed to dielectric loss from graphite and poly(o-phenetidine) matrix, and magnetic loss from NiCoFe2O4 nanoparticles

Thermal, dielectric and microwave absorption properties of polyaniline–CoFe2O4 nanocomposites

The present paper deals with the synthesis of conducting ferromagnetic polyaniline–CoFe2O4 (PC) nano-composites via one-step chemical oxidative polymerization of aniline in the presence of CoFe2O4 nanoparticles (30–40 nm). These nanocomposites of PC have been characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). Extended thermal analysis has revealed that the activation energy of these nanocomposites varies from 75.3 to 84.3 kJ/mol as com- pared to the activation energy of 50.3 kJ/mol for polyaniline-DBSA. In addition, dielectric and microwave absorption properties of the nanocomposites have been measured in the frequency range of 12.4–18 GHz (Ku-band) which demonstrate that more than 99% attenuation of microwaves (SEA = 21.5 dB) has been achieved using these nanocomposites. Systematic investigations reveal that the CoFe2O4 nanoparticles in the polyaniline matrix have phenomenal effect in determining the microwave absorption properties of the nanocomposites