GO-CNTs hybrids reinforced epoxy composites with porous structure as microwave absorbers

Abstract Foam structures with epoxy as the matrix and both carbon nanotubes (CNTs) and their hybrids with graphene oxide (GO-CNTs) as absorbers were fabricated, and their microwave absorbing and electromagnetic properties were investigated in the frequency range of 1–18 GHz. The fillers and bubbles were uniformly distributed in the composites. The complex permittivity and electrical conductivity of the composites increased as the fillers’ content increasing. The best performance of the reflection loss (RL) can be obtained for a foam structure with 0.5 wt% GO-CNTs, which had a RL peak value of −20dB with a −10 dB range of 5.3 GHz (10.8–16.1 GHz). Multi-layered structures were also discussed in this work, a RL peak value of −40dB with a −10dB range of 7.1 GHz (9.9–17 GHz) had been obtained by combining two foam structures, which are 2 mm thick 0.5 wt% GO-CNTs/epoxy and 1 mm thick 2.0 wt% GO-CNTs/epoxy. Furthermore, the −10dB range can reach 11.5 GHz (6.5–18 GHz) when combining 2.6 mm thick 0.5 wt% GO-CNTs/epoxy and 1.3 mm thick 2.0 wt% GO-CNTs/epoxy.