GATE (TF) Textile 2021 Question Paper Solution | GATE/2021/TF/05

Viscose rayon is a type of regenerated cellulose fiber that is made from wood pulp or cotton linters. The production process involves treating the cellulose with caustic soda to create a solution, which is then aged and treated with carbon disulfide to create a viscose solution. The viscose is extruded through a spinneret to create filaments, which are then chemically treated and spun into fibers. Viscose rayon is known for its softness, drapability, and ability to absorb moisture, and is used in a variety of applications, including clothing, home textiles, and industrial products.

Melt spinning is a process used in polymer science and engineering to create fibers from molten polymers. In this process, a solid polymer is melted, and then extruded through a spinneret to form continuous filaments. The filaments are then cooled and solidified to create fibers with the desired properties. Melt spinning is a versatile and efficient method for producing synthetic fibers, and is used to create a variety of materials, including polyester, nylon, and polypropylene.

Wet spinning is a method of producing fibers from a solution of the polymer dissolved in a solvent. In this process, the polymer solution is extruded into a coagulating bath that contains a nonsolvent, which causes the polymer to solidify and form a fiber. The coagulation process can be achieved by various means, such as using a bath of hot water or a chemical solution. Wet spinning is commonly used to produce fibers from materials such as rayon, acrylic, and spandex. The resulting fibers are then washed, stretched, and dried before they can be used for various applications.

Dry spinning is a method used to produce synthetic fibers such as acrylic, modacrylic, and spandex. In this process, a polymer solution is forced through the tiny holes of a spinneret and into a chamber where the solvent evaporates, leaving behind solid fibers. Dry spinning is called so because the solvent is evaporated from the polymer solution before it is extruded, unlike in wet spinning where the solvent is removed after the fiber is formed. This method is used for fibers that cannot withstand contact with water or other solvents during spinning.

Dry jet wet spinning is a process used to produce man-made fibers such as nylon and polyester. It is a combination of dry spinning and wet spinning methods. In this process, the polymer is dissolved in a volatile solvent, and then extruded through a spinneret into a stream of warm air that causes the solvent to evaporate. The resulting filament is then passed through a liquid bath, where it is coagulated and then drawn or stretched to orient the polymer chains and improve its strength and other physical properties. The process is called “dry jet” because the extruded filaments are exposed to a jet of air, and “wet” because they are then passed through a liquid bath.