Page 124 - Carbon Nanotube Fibres and Yarns

116 Carbon Nanotube Fibers and Yarns

Press system
v s v
v r
Fiber-supplying Fiber-collecting
system system

As prepared Rolled CNT
(A) (B) CNT fiber fiber

0.03
6 10 mm gauge length
3.76–5.53 GPa;
5
Average 4.34 GPa
Tensile strength (GPa) 4 3 2 Resistivity (Ω*cm) 0.02

0.01
0 1
0.00
0 2 4 6 8 10 12 14 0 20 40 60 80 100
(C) Strain (%) (D) Stretch %
Fig. 6.6 (A) Schematic diagram of experimental setup for the fabrication of twist-
less CNT fibers by a rubbing roller system, (B) schematic diagram of the experimental
setup for the densification of high-density CNT fibers by a pressurized rolling system,
(C) stress-strain curve of densified CNT fibers after the mechanical treatment, and
(D) electrical resistivity at room temperature vs the stretch ratio of two sets of an-
nealed SWNT fibers. ((A) Reproduced with permission from M. Miao, Production,
structure and properties of twistless carbon nanotube yarns with a high den-
sity sheath, Carbon 50 (2012) 4973–4983; (C) Reproduced with permission from
J.N. Wang, X.G. Luo, T. Wu, Y. Chen, High-strength carbon nanotube fibre-like rib-
bon with high ductility and high electrical conductivity, Nat. Commun. 5 (2014);
(D) Reproduced with permission from S. Badaire, V. Pichot, C. Zakri, P. Poulin, P. Launois, J. Vavro,
et al., Correlation of properties with preferred orientation in coagulated and stretch-aligned
single-wall carbon nanotubes, J. Appl. Phys. 96 (2004) 7509–7513.)

reported that the electrical resistance of single-walled CNT fibers obtained
by high-temperature annealing of a CNT/PVA composite fiber could be re-
duced by improving the CNT alignment by stretching, as shown in Fig. 6.6D.
The better CNT alignment of the stretched fibers enhanced the contact ar-
eas between the CNTs, resulting in their improved electrical performance.

6.6 Infiltration
Together with densification treatments, polymer infiltration is an effec-
tive method to improve CNT fiber strength. The reinforcement effect is
due to the enhanced inter-tube load transfer as well as the crystallinity