Page 129 - Carbon Nanotube Fibres and Yarns

Post-spinning treatments to carbon nanotube fibers 121

diameters of the CNT fibers treated at different epoxy concentrations.
The diameter of the infiltrated CNT fibers increased with increasing
epoxy concentration, from 9.5 ± 0.05 μm for 0 wt.% epoxy solution to
15.9 ± 0.14 μm for 50 wt.% the epoxy solution, as shown in Fig. 6.10B.
The surface morphologies of the CNT fibers infiltrated with 10, 30,
and 50 wt.% epoxy solutions are presented in Fig. 6.11. The epoxy was well
infiltrated into the fiber structure, and the amount of epoxy in the infiltrated
fibers increased with increasing epoxy concentration. Many pores and CNT
bundles were still visible in the 10 wt.% epoxy-treated fibers (Fig. 6.11A).
At higher epoxy concentration (30 wt.%), the amount of epoxy on the fi-
ber surface increased, resulting in reduced number of pores, but the CNT
bundles were still visible on the treated fiber surface, as shown in Fig. 6.11B.
The infiltration of the highest epoxy concentration employed in this study
(50 wt.%) results in no pores and only few CNT bundles visible on the
fiber surface (Fig. 6.11C), suggesting that a large amount of epoxy covers
the fiber surface. This increasing epoxy amount in the fiber structure was
the main reason for the increased diameters of the epoxy-infiltrated fibers.
Fig. 6.12 compares the tensile strength and Young’s modulus of the
CNT fibers infiltrated at different epoxy concentrations. When the epoxy

2µm 2µm
(A) (B)

2µm
(C)
Fig. 6.11 SEM images of surface morphology of the CNT fibers after being infiltrated
with (A) 10 wt.%, (B) 30 wt.%, and (C) 50 wt.% epoxy solutions.