Introduction
The
use of plasma in textile modification represents a great outlook for the improvement of older, energetically demanding, slow, and environment-polluting
treatment technologies. The application of plasma is eco-friendly and reduces
production costs due to energy savings and the reduction of processing times.
Moreover, plasma treatment offers the possibility to obtain textile finishes
without changing the key textile properties.
What is Wool fiber?
Wool
is the textile protein fiber that is obtained from sheep and other slaughtered
animals, including cashmere and mohair from goats, qiviut from muskoxen, hide
and fur clothing from bison, angora from rabbits, and many other types of wool
from camelids. The earliest fragments of the wool fabric have been found in Egypt
but Mesopotamia is the birthplace of wool.
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| Wool Fibers |
Wool contains a small percentage of lipids as well as proteins. In this case, it is chemically dominant textile cotton from cellulose which is relatively different.
What Is Plasma?
Plasma is a state of matter in which an ionized gaseous substance
becomes highly electrically conductive to the point that long-range electric
and magnetic fields dominate the behavior of the matter. Plasma states are seen
in contrast to other states: solid, liquid, and gas.
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| Nuclear Plasma |
Plasma is an electrically neutral medium of unlacing positive and negative particles. Although these particles are infinite, they are not free from the experience of not giving forces. Moving charged particles generate an electric current within a magnetic field, and any movement of a charged plasma particle affects and is affected by the fields created by the other charges. In turn, this governs collective behavior with many degrees of variation.
Three
factors define a plasma-
B.
Bulk Interaction: The length of screening (as defined above) is much shorter
than the physical size of the plasma. This criterion means that interactions in
most parts of the plasma are more important than their edges where boundary effects
can occur. If this criterion is satisfied, then plasma is quasineutral.
C. Plasma Frequency: Electronic plasma frequency is larger than electron-neutral collision frequency When this condition is valid, electrostatic interactions predominate over the processes of general gas dynamics.
There
are many ways to induce the ionization of gases. Such as-
a.
Glow discharge,
b.
Corona discharge,
c.
Dielectric Barrier discharge,
d. Atmospheric pressure plasma technique.
a.
Glow discharge
The oldest type of plasma technique is glow discharge and it is produced at reduced
pressure and provides the highest possible uniformity and flexibility of
any plasma treatment.
b.
Corona discharge
Corona
Discharge is formed at atmospheric pressure by applying a low frequency or
pulsed high voltage over an electrode pair, the configuration of which can be
one of many types.
c.
Dielectric Barrier Discharge
Dielectric-Barrier
discharge is formed by applying a pulsed voltage over an electrode pair of
which at least one is covered by a dielectric material.
d.
Atmospheric pressure plasma technique
The
atmospheric pressure has better stability, control, and reproducibility. Since
plasma cannot be generated in a complete vacuum the name vacuum pressure is
somewhat misleading and only refers to the low working pressures of such
systems.
However, choose to classify vacuum pressure plasmas into subcategories of low and medium pressures. Both these forms are suitable for application on textiles and progress continues to determine their effect on textiles.
Artificial
plasmas-
Most
artificial plasmas are generated by the application of electric or magnetic
fields through a gas. The plasma produced for a laboratory setting and
industrial use can generally be classified as:
The
type of power source used to generate the plasma—DC, AC (typically with radio
frequency (RF)), and microwave
The pressure they operate at—vacuum pressure (< 10 m Torr or 1 Pa), moderate
pressure (≈1 Torr or 100 Pa), atmospheric pressure (760 Torr or 100 kPa)
The
degree of ionization
Within the plasma—fully, partially, or weakly ionized
The
temperature relationships within the plasma—thermal plasma (Te = Ti = Tgas),
non-thermal or "cold" plasma (Te greater than Ti = Tgas)
The
electrode configuration used to generate the plasma
The magnetization of the particles within the plasma—magnetized (both ion and electrons are trapped in Larmor orbits by the magnetic field), partially magnetized (the electrons but not the ions are trapped by the magnetic field), non-magnetized (the magnetic field is too weak to trap the particles in orbits but may generate Lorentz forces).
Plasma treatment on wool fiber
In wool, the surface character of plasma treatment is limited to a small part of the fiber, in relation both to its mass and volume. Physical properties such as the fiber friction coefficient, dye diffusion, etc. depend on the highly-networked layer known as the epicuticle. Modifying this layer, without causing changes in the wool cortex, facilitates and accelerates some technological processes, including the dyeing of fibers. Dorota Biniaś worked on the effect of LTP on the dyeing process of woolen fabrics and found that LTP-treated samples proved to have bound the dye better than the unmodified sample. In addition, LTP damages an ultra-thin hydrophobic layer on the protective surface of the fiber. This process occurs only on the surface and does not damage the inner structure of keratin. Wool fibers were treated with LTP with different gases, namely oxygen, nitrogen, and a mixture of gases (25% hydrogen, 75% nitrogen), and it was shown that the surface composition of the LTP-treated wool, the fiber was found to vary differently with different plasma gases. The results have been similar to the previous reports, in which it was explained that the concentration of the functional groups influences the properties of the wool fiber.
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