Structure, Properties and Treatments of Carbon Nanotube Fibres

Abstract

Carbon nanotubes (CNTs) possess exceptional mechanical, thermal and electrical properties along their main axis, superior to those of most materials. These can be exploited on a macroscopic scale by assembling the CNTs into a fi bre with the nanotubes preferentially oriented parallel to each other and to the fibre axis. CNT fibres can be produced continuously, directly from the gas phase during CNT synthesis by chemical vapour deposition (CVD), and spun at rates of up to 70 m/min. Their combination of outstanding mechanical, electrical and thermal properties and low density (1 g/cm3) makes CNT fi bres a potential candidate for high-performance applications. The fi bre speci c strength and stiff ness are typically 1 GPa/SG and 50 GPa/SG, respectively; however, at small gauge lengths (< 2mm) they also show values of 6 - 9 GPa/SG strength and 180 - 390 GPa/SG sti ffness. The electrical conductivity of the CNT fibres is approximately 8 x 10^5 S/m and their thermal conductivity of the order of 50 W/mK. These properties derive from the long length, high alignment and efficient packing of the nanotubes in the fi bre. Further improvements to the fi bre structure and properties at long gauge lengths are possible through removal of impurities from the fi bre by annealing.