Page 88 - Carbon Nanotube Fibres and Yarns

Carbon nanotube-reinforced polymer nanocomposite fibers 81

6000
17.2 50
1s
4000 PAN
PAN/GO
E′ (MPa) PAN/C 60 2q (degree) 17.1 40
PAN/CNT
2000 17.0
2q (110,200)
16.9 Xc (%)
XS (A)
(A) 0 0 60 120 180 (B) 0 2 4 6 8 10 12 30
Time (min) Time duration (h)
Amorphous Amorphous
polymer Amorphous Crystalline Graphitic carbon
Crystalline polymer polymer structure
polymer
1s
Carbonization

(C)
Fig. 5.6 (A) Storage modulus versus dynamic strain durations for PAN film and C 60 /PAN,
GO/PAN, MWNT/PAN composite films; (B) plots of the structural parameters of MWNT/
PAN films versus dynamic strain durations [42]; and (C) schematic of PAN interphase
development during dynamic straining and the resulting carbonized structures [29].
(Source of (A) and (B): Y. Li, P. Zhou, F. An, Y. Liu, C. Lu, Dynamic self-stiffening and struc-
tural evolutions of polyacrylonitrile/carbon nanotube nanocomposites, ACS Appl. Mater.
Interfaces 9 (6) (2017) 5653–5659. Source of (C): Y. Li, Y. Yu, Y. Liu, C. Lu, Interphase develop-
ment in polyacrylonitrile/SWNT nano composite and its effect on cyclization and carboniza-
tion for tuning carbon structures, ACS Appl. Nano Mater. 1 (7) (2018) 3105–3113.)

of PAN chains. The structural change of the nanocomposites was also depen-
dent on the direction of the dynamic straining, that is, the growth direction
of PAN crystals was perpendicular to the straining direction, while there was
no structural change observed along the straining direction. A scheme of the
interphase growth during dynamic straining is shown in Fig. 5.6C. For PAN/
CNT nanocomposites, the interphase PAN would form graphitized struc-
tures during carbonization at a temperature between 1100°C and 1300°C.

5.2.3 Properties of CNT-containing fibers
Besides the improvement of mechanical properties, the incorporation of
CNTs in a polymer fiber can also affect other properties of the fiber, such as
glass transition temperature and thermal shrinkage, electrical conductivity,
thermal conductivity, and solvent resistance.
CNT restricts the polymer chain mobility in its vicinity. For PAN/
SWNT nanocomposite fibers, the glass transition temperature increased