Biomedical Engineering Reference
In-Depth Information
1.0
1.0
E = 1 Volt step @ 1/2 Hz
E = 2 Volt step @ 1/2 Hz
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0.0
0.0
−
0.2
−
0.2
−
0.4
−
0.4
−
0.6
−
0.6
−
0.8
−
0.8
−
1.0
−
1.0
2
3
4
5
6
7
8
2
3
4
5
6
7
8
Time (sec)
Time (se c)
1.0
1.0
E = 3 Volt step @ 1/2 Hz
E = 4 Volt step @ 1/2 Hz
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0.0
0.0
−
0.2
−
0.2
−
0.4
−
0.4
−
0.6
−
0.6
−
0.8
−
0.8
−
1.0
−
1.0
2
3
4
5
6
7
8
2
3
4
5
6
7
8
Time (sec)
Time (se c)
SAMPLE-28
FIGURE 3.21
Current responses to step voltages of 1, 2, 3, and 4 V for Taguchi sample 28.
Therefore, large organic hydrophobic ions such as TBA and TMA generate less force
than Li
+
- and Na
+
-based IPMNCs. An important aspect regarding the use of such
alkylammonim ions could be attributed to their large and bulky size relative to small
cations investigated.
Overall, the hydration process within the membrane in connection with the
electrophoretic effect is fairly complex in the sense that the mobile cations experience
a large viscous drag and, at the same time, exert force due to the generated strain
while they are moving through the water containing polymer network. The situation
can be interpreted that each cation with its connected clusters (Komoroski et al.,
1982) is shearing or rubbing past other cations and networks. This could increase
the viscous drag and lower the conductivity.
Overall, considering the hydrated volume of each cation, v[Li
+
] >> v[Na
+
] >
(v[K
+
], 0.5v[Ca
++
], 0.5v[Mg
++
] and 0.5v[Ba
++
]), and v[H
+
] (Atkins, 1982; Moor,
1972), one can see a general trend of force generation: Li
+
>> Na
+
> (K
+
, Ca
++
,
Mg
++
, and Ba
++
) > H
+
and (TBA and TMA). Another interesting note is that the
relaxation behavior of IPMNCs is less observable in TBA and TMA.
