Electromagnetic, morphological and structural characterization of microwave absorbers based on POMA/magnetic filament composites

Author(s)

Pinto, Simone de Souza ^[1] ; Barros Machado, Joao Paulo ^[2] ; Gomes, Newton A. S. ^[3] ; Rezende, Mirabel Cerqueira ^{[1, 3]}

Affiliation

^[1] Univ Fed Sao Paulo UNIFESP, Inst Sci & Technol, Rua Talim 330, Sao Jose Dos Campos, SP - Brazil

^[2] Natl Inst Space Res, Av Astronautas 1-758, Sao Jose Dos Campos, SP - Brazil

^[3] ITA, Praca Mal Ar Eduardo Gomes 50, Sao Jose Dos Campos, SP - Brazil

• Document type: Journal article
• Source: Journal of Magnetism and Magnetic Materials; v. 449, p. 406-414, MAR 1 2018.
• Web of Science Citations: 2

Abstract

This study aims to combine dielectric and magnetic properties of different materials in an unique composite. For this, poly(o-methoxyaniline), POMA, was chemically synthesized in situ on magnetic metallic filaments (MF). The obtained composite was inserted into an epoxy resin matrix in the proportions of 40, 50 and 70%, in weight (wt%). The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and electromagnetic measurements. On the last case, the measurements considered the reflectivity and the complex parameters of electrical permittivity and magnetic permeability in the frequency range of 8.2-12.4 GHz (X-band). Specimens with different thicknesses were evaluated by reflectivity. XRD results show that the filaments are based on Fe-a steel and SEM analyses show the good incorporation of POMA/MF in the epoxy resin composite. The complex parameters show that the real component of permittivity shows the largest variation with the POMA/MF concentration increasing in epoxy resin and the loss tangent indicates that the magnetic losses are preponderant on dielectric ones. The reflectivity measurements show that the 5 mm-specimen with 50 wt% of POMA/MF presents the best result of attenuation (-21.5 dB, i.e. above 99% of attenuation). Already, the sample containing 70 wt% shows the worst performance (up to -9.0 dB). The increase of POMA/MF concentration in epoxy resin confers maximum attenuation values for less thick specimens. The results show that the combination of dielectric and magnetic materials in a composite contributes for the improvement of microwave absorbing performance, and extends the possibilities of RAM processing with different characteristics. (C) 2017 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 14/02551-7 - Preparation of conducting composites based on magnetic substrates impregnated with the POMA-conducting polymer
• Grantee: Simone de Souza Pinto
• Support Opportunities: Scholarships in Brazil - Post-Doctoral