Nanometer-Sized Carbon Black and Fe3O4 Nanoparticles Incorporated into Polyamide-66 Composite Fibers and Woven into Three-Dimensional Fabrics for Electromagnetic Absorption

High-performance microwave absorption materials with broad electromagnetic absorption bandwidths and scalable architectures have been increasingly demanded in modern electric and telecommunications industries. Herein, we propose a flexible three-dimensional (3D) woven fabric with superior washability and electromagnetic-wave absorption capability using the nanoengineered carbon black (CB)-Fe₃O₄/polyamide-66 (PA-66) composite fibers that possess a unique core–sheath structure. Notably, the impedance matching and microwave attenuation of the proposed 3D fabric absorbers are realized by the dielectric–magnetic coupling effect of nanometer-sized CB and Fe₃O₄ nanoparticles within the constituent PA-66 fibers. The produced 3D fabrics showed superior mechanical properties with a tensile strength of 35 MPa, good softness with flexibility of drape coefficient up to 88.8%, and great air permeability with an air permeability of over 109 mm/s. At a weft density of 250 picks/10 cm, the fabric realized the best electromagnetic-wave absorption performance with a minimum reflection loss of −34.5 dB, owing to the good impedance-matched 3D orthogonal structures and integrated dielectric–magnetic fibrous networks of the 3D fabric. In particular, this performance could be well-maintained even after rinsing five times or folding to two layers. This study can provide a promising route to developing next-generation flexible electromagnetic absorption materials.