High density interfaces enhanced microwave absorption in multifunctional carbon nanotubes‐glass fiber‐epoxy composites

Abstract In this work, we fabricated and systematically investigated the mechanical and microwave absorption properties of multi‐walled carbon nanotube (MWCNT)—glass fiber (GF)—epoxy composites. The composites showed high electromagnetic (EM) wave absorption performance in a wide frequency range. The maximum reflection loss of the composites can reach to −48 dB at 24.5 GHz. The EM wave absorption of the composites strongly depends on MWCNT and GF contents and can reach to ~70% at 26.5 GHz; further, such dependence is peculiar, contradicting to the conventional wisdom, due to high density interfaces in the materials, which lead to multiple scatterings and multiple absorptions of EM waves. The tensile strength of the composites was enhanced to ~427 MPa with ~74 wt% GFs, that is comparable to that of commercial Al alloy 6061 (~300 MPa, but not much EM wave absorption). The composites have the potential as multifunctional microwave absorption and low‐weight structural materials without a need of additional coating.