Biomedical Engineering Reference
In-Depth Information
Figure 10.9
The bactericidal rate of Ag coated CNTs and Ag coated
pyrolytic carbon. Growth rate ~3.33 nm/min [40].
A carbon nanotube monolith without any binders was obtained
by Wang
et al
. using spark plasma sintering (SPS) [61].
In vivo
testing reveals that pure bulk carbon nanotubes are not a strongly
inlammatory substance and have no toxicity for bone regeneration.
They suggest that a binderless carbon nanotube monolith with a
strength matching that of bone could be a candidate bone substitute
material and a bone tissue engineering scaffold material [61]. The
SPS is a rapid sintering method, using self heating phenomena
within the powder. The SPS method generates spark plasma
between a powder particles, resulting in rapid temperature rise and
leading to a fully dense CNT monolith obtain in a very short time
(10 min), and at a relatively low temperate (1100
o
C) and pressure
(40 MPa). Figure 10.10 shows a carbon nanotube powder and
sintered carbon nanotube monolith [61]. The most important in
monolith fabrication is initial fast heating rate (200
o
C/min) for
activating the nanotubes surface, which are then sequentially
decreases (up to 5
o
C/min) for stress releasing and keeping the
nanotubes structure [61]. The density and mechanical properties of
the sintered CNT monolith are at the same level to those of bone (Table
10.2) [6], which shows that the CNT monolith could be attractive for
bone tissue repair. The strength of the CNT monolith was less than
that of conventional implant materials, but very similar to those of
bone, making it possible to achieve a suficient bone regeneration at
the tissue/material interface [61].
