Chemistry Reference
In-Depth Information
High-voltage electrode
Wool fibers
FIGURE 8.33
Experimental arrangement for treatment of wool fibers.
60
0.1000
30
2
20
40
0.0500
1
10
-0.0000
0
0
20
-10
-
1
0
-0.0500
-20
-30
-2
-20
-0.1000
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
(a)
(b)
Time [µs]
Time [µs]
FIGURE 8.34
(a): Typical discharge current and sustaining voltage using a sinusoidal voltage
pulse group. (b): Energy (up to 0.07J) fed in and power.
by multiplication of current and voltage and following integration (Figure 8.34b).
Discharge qualities and fed energy are ascertained by the height of the voltage
pulses, their duration, and number of pulses. In this manner, textile fibers can be
treated efficiently.
Figure 8.35 shows a thermal image during the plasma treatment of wool fibers.
The picture shows the results during the treatment with a continuous sine wave
voltage. The treatment is very different and the formation of single hot spots can
be observed. These can locally lead to high temperatures and to the destruction of
the fibers. With measures like the choice of a suitable gas space thickness (gap),
streaming of the gas, and sustaining with pulse groups, a steady treatment of the
wool fibers can be reached. The filaments are steadily distributed statistically. Their
formation is finer; above all, however, discharges are created in the hollow cavities
between the wool fibers. Such discharges in hollow cavities of insulators are known in
the electric engineering as partial discharges, and there they cause aging of insulators
and electrical breakdowns. Here, the discharges generate the active species directly
between the wool fibers in the system of many hollow interlinked cavities, and thus
they cause a very steady and effective plasma treatment.
The effect of plasma on the fiber surfaces occurs in a step-by-step process. In the
first step, a quick functionalization occurs through the formation and dismantling of
