What is plasma?
Irving Langmuir first used the term plasma in 1926 to describe the inner region of an electrical discharge. Later, the definition was broadened to define a state of matter in which a significant number of atom and/or molecules are electrically charged or ionised. The components present will include ions, free electrons, photons, neutral atoms and molecules in ground and excited states and there is a high likelihood of surface interaction with organic substrates. In order to maintain a steady state, it is necessary to apply an electric field to the gas plasma, which is generated in a chamber at low pressure. (Kan, 1999; Ganapathy, 2000; Pane, et al 2001; Allan, et al 2002).
Plasma, as a very reactive material, can be used to modify the surface of a certain substrate (typically known as plasma activation or plasma modification), depositing chemical materials (plasma polymerisation or plasma grafting) to impart some desired properties, removing substances (plasma cleaning or plasma etching), which were previously deposited on the substrate (Pane, et al 2001).
Plasma is any substance (usually a gas) whose atoms have one or more electrons detached and therefore become ionised. The detached electrons remain, however, in the gas volume that in an overall sense remains electrically neutral. Thus, any ionised gas that is composed of nearly equal numbers of negative and positive ions is called plasma. The ionisation can be effected by the introduction of large concentrations of energy, such as bombardment with fast external electrons, irradiation with laser light, or by heating the gas to very high temperatures.
A gas becomes plasma when the kinetic energy of the gas particles rises to equal the ionisation energy of the gas. When this level is reached, collisions of the gas particles cause a rapid cascading ionisation, resulting in plasma. If the necessary energy is provided by heat, the threshold temperature is from 50,000 to 1,00,000 K and the temperatures for maintaining a plasma range up to hundreds of millions of degrees. Another way of changing a gas into plasma is to pass high-energy electrons through the gas. The individually charged plasma particles respond to electric and magnetic fields and can therefore be manipulated and contained. The atmospheres of most stars, the gas within the glass tubing of neon advertising signs, and the gases of the upper atmosphere of the earth are examples of plasmas. On the earth, plasmas occur naturally in the form of lightning bolts and in parts of flames.
There are many different ways to induce the ionisation of gases. (1) Glow discharge, (2) Corona discharge, (3) Dielectric Barrier discharge.
Various plasma technologies used in textile
There are many different ways to induce the ionisation of gases.
(1) Glow discharge,
(2) Corona discharge,
(3) Dielectric Barrier discharge,
(4) Atmospheric pressure plasma technique.
Various application of plasma in textile.
APPLICATION MATERIAL TREATMENT
Hydrophilic finish PP, PET, PE Oxygen plasma, Air plasma
Hydrophobic finish Cotton, P-C blend Siloxane plasma
Antistatic finish Rayon, PET Plasma consisting of dimethyl silane
Reduced felting Wool Oxygen plasma
Crease resistance Wool, cotton Nitrogen plasma
Improved capillarity Wool, cotton Oxygen plasma
Improved dyeing PET SiCl4 plasma
Improved depth of shed Polyamide Air plasma
Bleaching Wool Oxygen plasma
UV protection Cotton/PET HMDSO plasma
Flame retardancy PAN, Cotton, Rayon Plasma containing phosphorus
