Biomedical Engineering Reference
In-Depth Information
6.
Second, because this recast Nafion is water soluble, an appropriate anneal-
ing was performed at an elevated temperature of 70
°
C so as to create
crystallinity. Usually, the temperature is raised at 150
C for further curing.
The annealing process can tailor mechanical and chemical stability of the
solution recast Nafion film.
°
The IPMNC sample was prepared by using 2-mm thick recast Nafion fabricated
by following the process just described. Later, platinum electroding was done on both
sides of the sample with a particle penetration depth of ~20 mm. Figure 3.58 shows
photographs of the IPMNC samples with the primary platinum electrode and secondary
gold electrodes. Another fabrication method is also described in figure 3.59.
The mechanical tensile behavior of an as-received Nafion (fully hydrated H
+
form, 16% H
2
O) was first measured and presented in figure 3.60. As can be seen,
the as-received Nafion clearly shows the electrostatic cross-linking and crystallinity-
induced tensile characteristics exhibiting an unclear yielding and strain-induced
further crystallinity, somewhat similarly to cross-linked elastomeric behavior. Also,
the normal stress-strain curve for the recast membrane (fully hydrated H
+
form, 9%
H
2
O) is superimposed. It clearly shows a distinct, plastically deformed behavior that
is an indication of weakened (or eliminated) electrostatic cross-linking relative to
dominating elastic forces.
The force/displace measurement was done separately in a cantilever beam con-
figuration: The tip force (truly the maximum force) was measured by a load cell at
An eight-finger synthetic muscle.
It has a thickness of approximately 2 mm.
A rod shape synthetic muscle.
It has a rectangular cross-section of
approximately 8 mm
×
8 mm.
A coil type synthetic muscle.
A circular shape synthetic muscle.
FIGURE 3.57
Various IPMNCs with three-dimensional shapes.
