Mechanical and thermal properties of carbon nanotubes in carbon nanotube fibers under tension-torsion loading

MW Niu and CX Cui and R Tian and YS Zhao and LL Miao and WZ Hao and JX Li and C Sui and XD He and C Wang, RSC ADVANCES, 12, 30085-30093 (2022).

DOI: 10.1039/d2ra05360h

In carbon nanotube fibers (CNFs) fabricated by spinning methods, it is well-known that the mechanical and thermal performances of CNFs are highly dependent on the mechanical and thermal properties of the inherent CNTs. Furthermore, long CNTs are usually preferred to assemble CNFs because the interaction and entanglement between long CNTs are effectively stronger than between short CNTs. However, in CNFs fabricated using long CNTs, the interior carbon nanotubes (CNTs) inevitably undergo both tension and torsion loading when they are stretched, which would influence the mechanical and thermal performances of CNFs. Here, molecular dynamics (MD) simulations were carried out to study the mechanical and thermal properties of individual CNTs under tension-torsion loading. As for mechanical properties, it was found that both the fracture strength and Young's modulus of CNTs decreased as the twist angle alpha increased. Besides, step-wise fracture happened due to stress concentration when the twisted CNTs are stretched. On the other hand, it could be seen that the thermal conductivity of CNTs decreased as alpha increased. This work presents the systematic investigation of the mechanical and thermal properties of CNTs under tension-torsion loading and provides a theoretical guideline for the design and fabrication of CNFs.

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