Page 14 - Carbon Nanotube Fibres and Yarns

6 Carbon Nanotube Fibers and Yarns

strength of commercial textile fibers against the theoretical specific strength of
their corresponding polymers in Fig. 1.3 (details are provided in Chapter 7).
The reason for using specific strength in the plot is to take into account of
any voids in fibers, which is a key feature for CNT fibers. Commodity textile
fibers such as cotton, polyester, and nylon only achieve between 2.5% and
5% of their theoretical specific strength. High-performance fibers, such as
Kevlar, spectra, and carbon fibers, which are produced with extremely high
care and thus have fewer defects, achieve between 5% and 10% of their theo-
retical specific strength. It is rare for commercial fibers to achieve more than
10% of their theoretical specific strength.
The theoretical specific strength (tenacity) of CNTs is 57.4 N/tex
3
based on the strength (130 GPa) and density (2.266 g/cm ) of monolayer
graphenes. The specific strength of future commercial CNT fibers will de-
pend on the degree of structural perfection that can be achieved, as rep-
resented by the vertical thick bar on the right-hand side of the plot. For
example, at 2.5% of the theoretical strength, similar to commodity syn-
thetic fibers, the CNT fiber will achieve a specific strength of 1.44 N/tex,
3
which translate into 1.87 GPa for a fiber density of 1.3 g/cm ; at 10% of

Fig. 1.3 Specific strength of commercial fibers plotted against the theoretical specific
strength of their corresponding polymers.