LAUSR

Abstract This review summarizes progress on structural composites with carbon nanotube (CNT) fibres. It starts by analyzing their development towards a macroscopic ensemble of elongated and aligned crystalline domains, alongside the evolution of the structure of traditional high-performance fibres. Literature on tensile properties suggests that there are two emerging grades: highly aligned fibres spun from liquid crystalline solutions, with high modulus (160 GPa/SG) and strength (1.6 GPa/SG), and spun from aerogels of ultra-long nanotubes, combining high strength and fracture energy (up to 100 J/g). The fabrication of large unidirectional fabrics with similar properties as the fibres is presently a challenge, which CNT alignment remaining a key factor. A promising approach is to produce fabrics directly from aerogel filaments without having to densify and handle individual CNT fibres. Structural composites of CNT fibres have reached longitudinal properties of about 1 GPa strength and 140 GPa modulus, however, on relatively small samples. In general, there is need to demonstrate fabrication of large CNT fibre laminate composites using standard fabrication routes and to study longitudinal and transverse mechanical properties in tension and compression. Complementary areas of development are interlaminar reinforcement with CNT fabric interleaves, and multifunctional structural composites with energy storage or harvesting functions.