The influence of carbonyl iron and magnetite ferrite on the electromagnetic behavior of nanostructured composites based on epoxy resin/buckypapers

Abstract

Due to their remarkable mechanical and electrical properties, carbon nanotubes (CNTs) and their composites are great candidates for materials with improved electromagnetic and electrical properties. Above all, when used in conjunction with magnetic particles, for example, carbonyl iron and ferrites, the energy losses can be improved, minimizing the microwave reflections. This work studies the influence of magnetic particles (carbonyl iron and magnetite ferrite) on the electromagnetic behavior of carbon nanotube buckypaper (BP) reinforced epoxy composites over the frequency range 8.2 – 12.4 GHz. Firstly, the carbonyl iron and magnetite ferrite were dispersed in the epoxy resin, and their electromagnetic properties were analyzed. Epoxy/carbonyl iron composites showed reduced reflection losses at 10 GHz (SER = 1.52–1.99 dB) and improved absorption results (SEA = 0.47–5.78 dB). Epoxy/magnetite samples showed higher SER and SEA than carbonyl iron samples, with values ranging around 1.72–3.93 dB and 0.43–7.21 dB at 10 GHz, respectively. The addition of carbon nanotube buckypaper in the carbonyl iron composites resulted in SEA values up to 19.68 dB at 10 GHz. Besides, the BP/magnetite composites showed SEA of 18.58 dB at the same frequency. The total shielding efficiency (SET) was reached with 40 % wt. of magnetite (SET = 21.60 dB, at 10 GHz) and 70 % wt. of carbonyl iron (SET = 23.43 dB, at 10 GHz). Despite the variation in the magnetic filler concentration, all ternary hybrid composites showed increased absorption properties. This behavior is attributed to the synergistic effect between both magnetic particles and carbon nanotube buckypaper on the shielding properties of the studied composites.