Carbon nanotube grafting for better electromagnetic shielding with carbon fiber/epoxy composites

Abstract Carbon fiber reinforced polymer (CFRP) composites are rapidly substituting metals as load‐bearing structural components in space and defense applications. While their mechanical properties are sufficiently high, their capability to shield electromagnetic radiation needs improvement to meet current and future requirements. We demonstrate a novel method of enhancing the electromagnetic interference (EMI) shielding capability of conventional CFRP. We have grafted carbon nanotubes (CNTs) directly onto the surface of carbon fiber fabric using chemical vapor deposition (CVD) technique before incorporating them into the composite. The efficacy of this approach is assessed by comparing the DC electrical conductivity and EMI shielding effectiveness of CNT grafted CFRP with conventional CFRP. CNT‐grafted CFRP laminates show significant improvement in anisotropic electrical conductivity: (along fiber length) by 150%, (transverse to the fiber length) by 407%, and (through‐the‐thickness) by 476%, relative to conventional CFRP. The increase in electrical conductivity improves the EMI shielding capabilities of CNT grafted CFRPs significantly. Moreover, the relative improvement in the EMI shielding performance is direction‐dependent with better shielding performance when fibers are aligned with the incident electric field. EMI shielding effectiveness of CNT‐grafted CFRP laminates increases by 30% (≈55 dB) at 8.75 GHz relative to the conventional CFRPs. Finally, it is shown that CFRP laminates with grafted carbon fibers perform much better than laminates when CNTs are added as a filler to the epoxy. Highlights Grafting carbon nanotubes on the surface of carbon fiber improves their electrical conductivity. Electromagnetic shielding properties of carbon fiber/epoxy composite increase after carbon nanotube grafting on the fiber surface. The improvement in shielding behavior is primarily due to the absorption of electromagnetic waves. Carbon nanotube grafting on the carbon fiber fabric is an efficient strategy to improve the shielding performance of conventional composites.