Polyaniline–antimony oxide composites for effective broadband EMI shielding
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Conducting polyaniline (PAni)–antimony trioxide (Sb2O3) composites with different weight percentages (wt%) of Sb2O3 in PAni have been synthesized by in situ chemical oxidative polymerization. The composites were structurally and morphologically characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Measurements of electromagnetic interference (EMI) shielding, complex permittivity and microwave absorbing as well as reflecting properties of the composites were carried out in the frequency range of 8–18 GHz, encompassing the microwave X and Ku bands of practical relevance. All the computations are based on microwave scattering parameters measured by transmission line waveguide technique. It is observed that the presence of Sb2O3 in the PAni matrix affects the electromagnetic shielding and dielectric properties of the composites at microwave frequencies. The composites have shown better shielding effectiveness (SE) in both the X (SE in the range −18 to −21 dB) and Ku (−17.5 to −20.5 dB) bands. ε′ and ε′′ values of the PAni–Sb2O3 composites are in the range of 64–37 and 63–30, respectively, in the frequency range of 8–18 GHz. Dielectric measurements indicated the decrease in dielectric constant with the increase in wt% of Sb2O3. The results obtained for the reflection and absorption coefficients indicated that PAni–Sb2O3 composites exhibit better electromagnetic energy absorption throughout the X and Ku bands. The results indicated that PAni–Sb2O3 composites can be used as potential microwave absorption and shielding materials.