Page 127 - Carbon Nanotube Fibres and Yarns

Post-spinning treatments to carbon nanotube fibers 119

900
800 (B) No irradiation
Irradiated
(A) 700
600
Stress (MPa) 500
400
300
200
100
0
0 0.02 0.04 0.06 0.08
10um
Strain
(C) 250 1×10 13 atoms/cm 2 (D)
Unirradiated
200
Stress (MPa) 150

100
50

0
0 1 2 3 4 5 6 7 8
Strain (%) 300nm
Fig. 6.9 (A) CNT fibers spun from CNT array for gamma irradiation treatment, (B) stress-
strain curve of the gamma irradiated and unirradiated CNT fibers, (C) stress-strain curves
of the unirradiated and irradiated fibers by ion beam, and (D) SEM of the fiber location
with good conditions for ion beam welding (encircled region).

Gigax et al. [60] investigated the effects of proton irradiation on
the mechanical properties of the CNT fibers spun from CNT arrays.
The posttreated CNT fibers were found to have higher tensile strength
and lower fracture strain after the irradiation treatment, as presented in
Fig. 6.9C. This might be explained by the fact that the CNTs within
bundles of the irradiated fibers were tightly packed and inter-tube
linkages were likely formed in these regions. The encircled region in
Fig. 6.9D might be a point of bonding since these CNTs were com-
pressed by shear forces from the fiber production process. The ID/IG
ratio decreased at low ion fluence, which indicates ion beam-induced
defect repair. The repair might be explained by a thermal effect from
the local beam heating and an athermal effect through the formation of
mobile point defects and defect recombination with those introduced in
the production process [60].