Improvement of the tensile strength of carbon nanotube fibers to 12.5 GPa by fluidics-induced alignment and densification

Achieving the superior tensile strength of individual carbon nanotubes (CNTs) in macroscopic fibers depends on how CNTs are assembled. This study reports a fluidics approach: spraying high-velocity ethanol to scour and shrink pre-made CNT fibers. Experimental measurements show that the continuous scouring and shrinking induce significant improvements of the CNT alignment and packing density, leading to large increases of the van der Waals forces between CNTs and thus the tensile strength of the fibers. Under optimal conditions, the new CNT fibers achieve a specific tensile strength of 7.5×106 N⋅m⋅kg⁻1 (or 7.5 N⋅tex⁻1) and absolute strength of 12.5 GPa, approaching the lower limit of individual CNTs. They also exhibit a high Young’s modulus of 370 GPa, electrical conductivity of ~3×106 S⋅m⁻1, and thermal conductivity of ~968 W⋅m⁻1⋅K⁻1. This fluidics approach offers a promising route to develop high-performance CNT materials comparable to CNT individuals. Scouring and shrinking using fast flow of ethanol induced large improvements of carbon nanotube alignment and packing density and thus the tensile strength of the fiber to 12.5 GPa.