Page 75 - Carbon Nanotube Fibres and Yarns

Solution-spun carbon nanotube fibers 67

modulus, and elongation at break for these CNT fibers were 1.0±0.2 GPa,
120±50 GPa, and 1.4±0.5%, respectively. CNT length, aspect ratio, and
purity are key to strength improvements. A higher number of walls low-
ers the specific strength. Due to the much shorter CNT length used, the
acid-solution spun fibers achieved lower strength than solid-spun CNT
fibers. The higher modulus was principally attributed to the high CNT
orientation in the resulting fibers, as shown in Fig. 4.3.
The most prominent characteristics of the acid solution-spun CNT fi-
bers were their much higher electrical and thermal conductivity than the
solid-spun CNT fibers. The acid solution-spun fibers displayed an average
electrical conductivity of 2.9±0.3 MS/m (resistivity of 35±3 μohm cm) at

(A) (B)
10

8
Intensity (a.u.) 6 4 j

2

0
0 50 100 150 200 250 300 350
(C) j(°)
Fig. 4.3 (A) SEM of CNT fiber surface and (B) cross-section cut by focused ion beam,
showing a partially dog-boned structure. (C) WAXD azimuthal scan of the fiber, ex-
hibiting a FWHM of 6.3 degree corresponding to a Herman orientation factor of 0.996
[14]. (Reprinted with permission from D.E. Tsentalovich, R.J. Headrick, F. Mirri, J. Hao,
N. Behabtu, C.C. Young, et al. Influence of carbon nanotube characteristics on macroscopic
fiber properties. ACS Appl. Mater. Interfaces 9(41) (2017) 36189–36198.)