Category Archives: Technical textiles

Plasma treatment of textiles -II

Surface Modification Modes:

Ablation

The ability of plasma processing to break down weak covalent bonds in a polymer through bombardment with high-energy particles is known as ablation. This affects the outermost molecular layers of the substrate exposed to the plasma, which boils off and is removed by the vacuum. Because the chemistry of any layers of surface contamination is also generally made up of weak C-H bonds, plasma treatment can remove contaminants such as oil films or injection molding additives, thereby leaving behind a uniformly clean and active polymer surface.

Cross-linking

Cross-linking is the setting up of chemical links between the molecular chains of polymers. Plasma processing with inert gases can be used to cross-link polymers and produce a stronger and harder substrate micro surface. Under certain circumstances, cross-linking through plasma treatment can also lend additional wear or chemical resistance to a material.

Activation

The replacement of surface polymer groups with chemical groups from the plasma is called activation. During activation, the plasma breaks down weak bonds in the polymer and replaces them with highly reactive carbonyl, carboxyl, and hydroxyl groups. Activation can also be performed with amino groups or other functional groups. The resulting change in substrate characteristics will be determined by the type of chemical groups incorporated into the surface.

Deposition

In plasma deposition, a thin polymer coating is formed at the substrate surface through polymerization of the process gas. Depending on the selection of the gas and process parameters, these thin coatings can be deposited with various properties or physical characteristics. Coatings produced in this manner through plasma deposition exhibit different properties than films derived from conventional polymerization, including a high degree of cross-linking and extremely strong adherence to the substrate. Read the rest of this entry

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Plasma treatment of textiles -I

Plasma:

Plasma is defined as an ionized gas containing both charged and neutral species, including free electrons, positive and/or negative ions, atoms, and molecules. The overall state of plasma is considered neutral with the density of electrons and negative ions being equal to the density of the positively charged ions, known as plasma quasi-neutrality. In order to form and sustain plasma, an energy source capable of producing the required degree of ionization must be used. Either direct current (DC) or alternating current (AC) power supplies may be used to generate the electric field required for plasma generation. For many industrial types of plasma, radio frequency (RF) power supplies are used, usually at a standard frequency of 13.56 MHz. Plasma generation may also be performed at various pressures, including low (vacuum), atmospheric, or high pressure.

Basic Principle of plasma: In elementary physics reference is often made to the three states of matter: Solid, Liquid and Gas. However, there is a fourth state: Plasma.

States of matter

Fig: States of matter.

To convert a solid to a liquid energy is imparted to the solid, usually in the form of heat; similarly to convert a liquid to a gas. It is not therefore surprising that to convert a gas to a plasma, energy also needs to be imparted to the gas. The energy disassociated electrons from the gas atoms through atomic particle collisions. This occurs randomly, which means the energized gas is a mixture of ions, freed electrons, photons and neutral atoms (those yet to lose electrons). If a solid or liquid substance is introduced into the plasma, the high energy gas particles of the plasma will penetrate and collide with atoms or molecules several nano-meters into the solid or liquid, dissociating those electrons and bringing those atoms or molecules to an excited state to be part of the plasma. This means that the high energy particles of the plasma will continuously etch away a several nano-meter layer of a solid or liquid substrate for as long as the material is in contact with the energized gas.  Read the rest of this entry

Examples of Textiles Used in Agriculture

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LANDSCAPE FABRIC

Landscape fabric is used for weed control, a central element in achieving low-maintenance landscaping. Effective weed control means a reduction in actual weeding or in herbicide use-both unsavory landscaping tasks. Thermally spunbonded fabrics are said to be more effective than woven or needle punched geotextiles in preventing fine roots and rhizomes from penetrating the fabric. While woven fabrics are very strong, they offer many spaces for weeds to penetrate. Needle-punched fabrics have loose threads of material that plants can easily grow through. As for thermally spunbonded fabrics, these have fibers fixed in place, keeping roots from penetrating.

WIND PROTECTION FABRIC

Knitted windshield constructed from a commercial grade of U.V. stabilized yarn are often used to protect crops & structures from wind damage. Air exhaust deflection fabrics are otherwise most useful in odor control. These are often seen in swine and dairy house production. Wind protection fabric is available in a variety of aesthetically pleasing colors so structures won’t by an eyesore on the farm. Read the rest of this entry

Medical Textiles

Medical Textiles

Medical Textiles

Definition: A general term which describes a textile structure which has been designed and produced for use in any of a variety of medical applications, including implantable applications.

An important and growing part of the textile industry is medical, hygiene and health sector. The extent of growth is due to the development and improvement of knowledge in both textile as well as medical sector.

The engineering approach to develop textile products that will be suitable for medical and surgical application should possess a combination of the following properties

Strength, flexibility, and sometimes moisture and air permeability.

Materials include natural fibre, monofilament as well as multifilament yarns.

 The textiles used in medical and surgical purposes can be classified as follows:

  • Nonplantable materials-Wound dressing, bandages, plasters etc.
  • Extracorporeal devices– artificial kidney, liver, and lung
  • Implantable materials-suture, vascular grafts, artificial ligaments, artificial joints, etc.
  • Healthcare/hygiene products-bedding, clothing, surgical gowns, cloths, wipes etc. Read the rest of this entry

Firefighters Turnout Gear

Application of Automobile Textiles

A comprehensive study about the automobile textiles.

 

A Video from fibre to fashion may be helpful in this regard.

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