Page 69 - Carbon Nanotube Fibres and Yarns

P. 69

CHAPTER 4

Solution-spun carbon

nanotube fibers

Menghe Miao
CSIRO Manufacturing, Geelong, VIC, Australia

4.1 Introduction
In the production of regenerated and synthetic textile fibers, a polymer
material is converted into a fluid state and spun into a continuous bundle
of fibers by extrusion through a spinneret. Polymer fibers can be produced
using a number of extrusion techniques, known as wet spinning, dry spin-
a
ning, melt spinning, gel spinning, and electrospinning . In wet spinning,
a polymer is dissolved in a solvent for spinning. Typically, the spinneret is
submerged in a chemical bath that causes the fiber to precipitate, and then
solidify, as it emerges.
The solid-spun carbon nanotube fibers and yarns discussed in Chapters 2
and 3 require the carbon nanotubes to be organized in a specific man-
ner, either in vertical arrays (forests) that can be drawn into a continuous
CNT network, or in a continuous stream drawn out directly from a CNT-
synthesis furnace. These approaches do not lend themselves to the typical
easy scale-up of chemical processes and limit the options for process and
material optimization. It would be ideal that carbon nanotube fibers can be
produced from carbon nanotubes without being limited to a specific format
of organization. This way, carbon nanotubes can be optimized according to
their required properties rather than their organization for fiber manufac-
turing. A good example is the production of textile fibers from polymers in
which polymer synthesis and fiber extrusion are independent of each other.
CNTs tend to form bundles rather than dissolving because of the strong
van der Waals forces between them. Various spinning methods have been
investigated for spinning CNT composite fibers and pure CNT fibers [1, 2].
Obviously, melt spinning is an option only for CNT-containing thermoplas-
tic composite fibers, not for pure CNT fibers.
a https://en.wikipedia.org/wiki/Spinning_(polymers).

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