Biomedical Engineering Reference
In-Depth Information
7.2.4 Applications of carbon nanotubes
As already mentioned, the notable physical and mechanical properties of
CNTs suggest numerous scientific and engineering applications such as
supercapacitors, transparent electrodes for organic light emitting diodes,
lithium ion batteries, nanowires, field-effect transistors, molecular switches,
sensors and filters. The conductivity, robustness, high surface area,
accessible network formation and facile functionalization of CNTs are
promising features for use as electrochemical electrodes and catalyst
supports. Catalytically active sites can be used in fuel cells, immobilization
of biomacromolecules and for organic reaction catalysis. In addition, CNTs
can be used in the fields of catalysis, biomedical and mechanical
applications, and as nanoscale reinforcing elements in composites to achieve
improved properties (Schnorr and Swager, 2011).
For mechanical and structural applications, which are of relevance in the
context of the present chapter, pure CNT arrays can be shaped into bundles,
ropes and strands several centimetres in length. Two-ply yarns of CNTs can
also be formed, which can be assembled into sheets of a meter length and a
width of a few centimeters. Such arrays can be impregnated with other
materials to make composites, a particular example of a route to CNT-
based structural composites.
7.2.5 CNTs in polymer, metal, and ceramic composite
matrices
CNTs have emerged as potentially outstanding reinforcing agents for use in
metals (Bakshi et al., 2010), polymers (Shaffer and Sandler, 2007), and
glasses and ceramics (Cho et al., 2009) to overcome intrinsic limitations of
these materials and to impart new properties and functionalities. For
example, CNTs are usually introduced in polymeric and metallic matrices to
increase strength and stiffness along with other functional properties.
Glasses and ceramics incorporated with CNTs can exhibit reduced
brittleness to become structurally more reliable materials (Cho et al.,
2009). In addition, CNTs can offer improvements in the thermal and
electrical properties of inorganic matrices.
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7.3
Glass and glass-ceramic matrix composites
The versatility of glasses and glass-ceramics in compositions, properties and
processing makes them an attractive choice to be used as matrix materials in
composites for applications including aerospace, automotive, electronics,
biomedical and other specialized fields (Boccaccini, 2002). Silicate glasses
can be produced with a broad range of chemistries to control the fiber/
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