Page 84 - Carbon Nanotube Fibres and Yarns

Carbon nanotube-reinforced polymer nanocomposite fibers 77

Fig. 5.3 SWNT/PAN (1 wt%) fiber (A1) SEM image of a tensile fractured surface, (A2)
HRTEM image and schematic of a SWNT fibril, (A3, A4) HRTEM lattice images of same
fibril [27]; (B) the fracture surfaces of SWNT/PAN (0.5 wt%) films (B1 → B2 → B3) SEM
images and diameter distributions of the fibrils on the fracture surfaces along with
interphase development [29]. (Source of (A1) and (A2): H.G. Chae, M.L. Minus, S. Kumar,
Oriented and exfoliated single wall carbon nano tubes in polyacrylonitrile, Polymer 47 (10)
(2006) 3494–3504. Source of (B): Y. Li, Y. Yu, Y. Liu, C. Lu, Interphase development in polyac-
rylonitrile/SWNT nano composite and its effect on cyclization and carbonization for tuning
carbon structures, ACS Appl. Nano Mater. 1 (7), (2018), 3105–3113.)

surface of SWNT/PAN films exhibited protruded nanofibrils (Fig. 5.3B)
which indicated that the interphase PAN possessed better mechanical prop-
erties than matrix and the fractures occurred in between interphases and
matrixes [29]. Along with the development of interphase structures under
external stimulations, the diameter of these fibrils significantly increased.
In terms of the strength or modulus reinforcement efficiency of CNTs
in nanocomposites, there are reports of extremely high values exceeding
the intrinsic properties of CNTs [30, 33], which were ascribed to the ex-
istence of high-quality interphase structures. The properties and thickness
of interphase are affected by CNT type, polymer type, and processing
method/conditions, which make it hard to differentiate the reinforcement