Biomedical Engineering Reference
In-Depth Information
TABLE 4.5
LiOH PAN in LiOH Solution
Initial
length (in.)
Initial
expansion (in.)
After being
anode (in.)
After being
cathode (in.)
Trial 1
1.000
1.300
1.250
1.400
Trial 2
1.000
1.300
1.188
1.063
Trial 3
1.000
1.100
1.000
1.000
Electrical activation of PAN fibers (LiOH) in LiOH
1.600
1.400
1.200
1.000
0.800
0.600
0.400
Trial 1
Trial 2
Trial 3
0.200
0.000
Initial
length (in.)
Initial
expansion (in.)
After being
anode (in.)
After being
cathode (in.)
FIGURE 4.34
Electric activation of PAN fibers (LiOH) in NaOH.
Upon being placed in the solution, the fibers expanded on average from 1 to 1.2 in.
After acting as anodes, the fibers on average reduced in size to 1.146 in. After acting
as cathodes, the fibers on average increased in size to 1.15 in. We believed that the
LiOH solution contained too much OH
-
ions so as to force the PAN maintaining the
expanded state. However, at this moment, the true role of OH
-
is not well understood.
A counterexperiment with a low concentration of HCl as a solution is planned to
investigate the effect of H
+
that potentially predetermines the contracted state but allow-
ing expansion once OH
-
ions are generated. Our previous PAN actuation mechanism
described in figure 4.24 cannot describe this observation fully.
Fibers that had been boiled in sodium hydroxide did the worst with electrical
activation (see table 4.6 and fig. 4.35). Upon being placed in sodium chloride
solution, they increased on average from 1 to 1.07 in. After acting as anodes, the
fibers on average reduced in size to 0.97 in. Acting as cathodes, they brought about
an average increase in size of 1.02 in.
Based upon these observations, it was decided to dynamically monitor the
solution pH conditions and the generative force (or displacement) simultaneously.
The proper setup is shown in figure 4.36.
