The name is absent

33

Based on previously-reported parameters for similar synthesis, the
parameters in Table 2.2 were selected for the growth of the A-CNTs for this study. A
representative sample of the A-CNTs grown is displayed in Figure 2.10, where it can
be seen that the CNTs are considerably taller than those grown via pre-deposited
catalyst CVD. TEM images of these CNTs (Figure 2.11) reinforce this and also clearly
show that the CNTs, while not perfectly crystalline, are graphitic in the outer layers.
The coating at the "bottom" of the CNTs is much thinner, indicating less
pyrolized∕amorphous carbon since this region of the CNT was synthesized only
shortly before the growth terminated, and the large spots are iron nanoparticles
which are embedded in the walls of the CNTs. In the SEM images of these three
regions in Figure 2.12, we also observe that the alignment of the "top" of the CNTs is
much more anisotropic as compared to the "bottom", where two mechanisms may
be contributing to a loss of general alignment; these methods include: 1) the weight
of the thicker CNTs may be inhibiting the alignment, causing more “waviness" in the
CNTs, and 2) the constant injection of fresh catalyst is causing "new" CNTs to grow,
which are not growing normal to the substrate, causing additional Isotropicity of the
CNTs in this region.

2.3. Comparison of A-CNTs for Infiltrated Composite Applications

The first comparison that can be made between the CNTs grown by these
two different methods is the lengths that can be grown. The pre-deposited CVD
technique used here has not been reported as being able to grow CNTs much longer
than the 2.5 mm forests grown for this study. When growing A-CNTs for composite

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