Aligned carbon nanotube composite belts stitching of laminated composites for enhanced fracture toughness and enriched functionalities

Abstract Realizing the full potential of advanced fiber reinforced polymeric composites has been impeded by their weak interlaminar performance. Herein, a whole‐through‐thickness stitching strategy was proposed to address this key challenge by using ultrathin, high performance aligned carbon nanotube (CNT) composite belts as stitching sutures. During the fabrication of aligned CNT composite belts, the as‐made CNT belts that consist of randomly orientated CNTs were firstly stretched before resin infiltration. It has been found that the tensile strength and modulus of aligned CNT composite belts reached 1126.9 MPa and 56.2 GPa, with an improvement of 227.9% and 726.5% than those of unstretched composite belts, respectively. After stitching, the Mode I interlaminar fracture toughness and through‐thickness electrical conductivity of carbon fiber reinforced laminated composites was enhanced by 138.7% and 426.7%, respectively, which was mainly due to the bridging effect of strong and conducting CNT belts. In addition, the interlaminar crack propagations can be in situ monitored by tracking the resistance variation of the stitched laminates under loading. Thus, this stitching strategy provides an effective approach to not only enhance the structural performance of fiber reinforced polymeric composites, but also enrich their functionalities.