Biomedical Engineering Reference
In-Depth Information
6
µ
m
Acc V
10.0 kV
Spot
??4
Magn
??
×
Det
SE
WD
10.4
Exp
1
Hivac
(a)
pan2 3.0 kV 11.9 mm
×
15 ?? SE(U) 2/21/02
3 um
(b)
pan1 3.0 kV 11.9 mm
×
5??k SE(U) 2/21/02
10.0 um
(c)
FIGURE 4.81
Spun PAN nanofibers. (a) A Phillips XL30 ESEM using an accelerating
voltage of 10 kV was employed to take this SEM photograph; (b) ESEM image of the
polyacrylonitrile nanofibers spun at 1 kV/cm; (c) PAN nanofibers (~300 nm diameter). Hitachi
4700 was used (an acceleration voltage of 3 kV).
turn determine the amount of free nitrile groups left to be converted to carboxylic
acids during saponification. Figure 4.82 shows a C13 NMR spectrum of saponified
PAN fibers. Overall, it is anticipated that PAN should transit from a linear chain
structure (or zigzag) to a planar structure that would be related to pyridine
rings/cyano groups via cross-linking. Although the PAN fibers were tested at a dry
state, it appears that the cyano group is weaker and the carboxyl group stronger after
