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Improved Electromagnetic Interference Shielding Response of Poly(aniline)-Coated Fabrics Containing Dielectric and Magnetic Nanoparticles

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journal contribution
posted on 21.06.2012, 00:00 by Parveen Saini, Veena Choudhary, N. Vijayan, R. K. Kotnala
Composite absorbers based on conducting fabrics possessing moderate conductivity and dielectric/magnetic properties were prepared by in situ incorporation of nanoparticles of BaTiO3 (15–25 nm) or Fe3O4 (25–40 nm) within coated poly­(aniline) (PANI) matrix. The X-ray diffraction patterns and transmission electron microscopy images confirmed the formation of PANI coating and incorporation of BaTiO3 or Fe3O4 nanoparticles. Scanning electron microscopy images show formation of thick and uniform coating of PANI over individual fibers and in interweave regions. The dielectric studies show that incorporation of BaTiO3 lead to enhancement of dielectric properties of PANI whereas magnetization measurements revealed that incorporation of Fe3O4 resulted in noticeable improvement in magnetic properties with saturation magnetization of 17.9 emu/g. The Ku-band (12.4–18.0 GHz) shielding studies revealed that pure PANI-coated fabric show total shielding effectiveness (SET) of −15.3 dB which enhanced to −16.8 and −19.4 dB after incorporation of BaTiO3 and Fe3O4 nanoparticles respectively. Such an improvement can be attributed to the better matching of input impedance, reduction of skin depth, and additional dielectric/magnetic losses. The high value of absorption-dominated SET (i.e., 97–99% attenuation) and specific shielding effectiveness value of 17–20 dB cm3/g demonstrate the potential of these fabrics as promising microwave-shielding material. In addition, these fabrics also display good antistatic response with static charge decay time of only 0.11 s.