Frequency‐selective electromagnetic interference shielding carbon spacer yarn fabric/polyurethane foam composites

Abstract 3D fabric‐reinforced composites with electromagnetic interference (EMI) shielding performance are in urgent demand to deal with the electromagnetic (EM) pollution. In this work, carbon spacer fabrics/polyurethane foam (CSF/PUF) composites were prepared via in situ integration of PUF with fabrics. Their EMI shielding and frequency‐selective performances were realized via designing 3D fabric. CSF/PUF possesses two types of Fabry‐Pérot cavities that generated incident EM waves' resonances according to the quarter‐wavelength theory. The average total EMI shielding effectiveness (SE_T) of 3CSF/PUF was 69.6 dB in the X band. The maximum EMI SE_T of 3CSF/PUF was up to 83.2 dB in 9.7 GHz. The peaks of EMI SE move to the high‐frequency region with the increase of carbon spacer yarns' density. Moreover, CSF acted as a reinforcement role and significantly improved the mechanical properties of PUF. The peak stress under compression, three‐point bending and low‐velocity impact increased by 4.2‐, 5.6‐, and 4.9‐folds, respectively. CSF/PUF also exhibited good thermal insulation properties, maintaining a temperature difference of at least 19.5°C across its thickness at 60°C. The as‐prepared spacing yarn carbon fabric‐reinforced composite foams may raise an interest to explore multifunctional EMI materials via fabric structure design.