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Thursday, September 10, 2015

Raw materials used in Textile Industries

Introduction
Raw material (RM) is the primary substance which is used as an input to a production process for subsequent modification and finally modified into a finished good. Raw materials may be in processed or unprocessed state. Most of the times raw materials are natural resources such as cotton, oil, rubber etc. They are also altered to be used in different processes before being used in the final manufacturing process. So we can say that, the processed or unprocessed materials which are used to produce final textile products are called TRM.

Types of TRM
TRM may be of different types as follows –
  • Fibre
  • Yarn
  • Fabric
  • Dyes
  • Chemicals and Auxiliaries
Fibre
The textile industries use different types of fibres which are derived from nature or manually produced. These fibres are used to produce dresses, towels, blankets etc. Some of these fibres were known and used in the earlier years of civilization, as well as in modern times. Other fibres have acquired varied degrees of importance in recent years. The factors influencing the development and utilization of all these fibres include their ability to be spun, their availability in sufficient quantity, the cost or economy of production, and the desirability of their properties to consumers.

Textile raw materials

Classification

Type
Name of Fibre
Source or Composition
Vegetable
Cotton
Cotton ball (Cellulose)
Flax stalk (Cellulose)
Jute stalk (Cellulose)
Hemp or abaca stalk (Cellulose)
Agave leaf (Cellulose)
Kapok
Kapok tree (Cellulose)
Ramie
China grass (Cellulose)
Coir
Coconut husk (Cellulose)
Pina
Pineapple leaf (Cellulose)
Animal
Sheep (Protein)
Silkworms (Protein)
Hair
Hair bearing animals (Protein)
Mieral
Varieties of rocks (silicate of magnesium and calcium)
Cellulosic
Cotton linters or wood
Acetate
Cotton linters or wood
Triacetate
Cotton linters or wood
Noncellulosic Polymers
Aliphatic polyamide
Aramid
Aromatic polyamide

Dihydric alcohol and terephthallic acid
Acrylonitrile (at least 85%)
Modacrylic
Acrylonitrile (35% - 84%)
Polyurethane (at least 85%)
Olefin
Ethylene or propylene (at least 85%)
Vinyon
Vinyl chloride (at least 85%)
Saran
Vinylidene chloride (at least 80%)
Novoloid
Phenol based novalac
Polycarbonate
Carbonic acid (polyester derivative)
Polybenzimidazole
Tetraminobiphenyl and diphenyl isophthalate
Alginate
Calcium alginate
Fluorocarbon
Tetrafluoroethylene
Graft
Molecular graft of polymers
Matrix
Mixture of polymers
Anidex
Monohydric alcohol and acrylic acid
Lastrile
Acrylonitrile ((10-50%) and a diene
Nytril
Vinlylidene dinitrile (at least 85%)
Vinal
Vinyl alcohol (at least 50%)
Protein
Azlon
Corn, soybean
Rubber
Rubber
Natural or synthetic rubber
Metallic
Metal
Aluminum, silver, gold, stainless steel
Metal
Silica sand, limestone
Ceramic
Alumina, silica

Yarn
Yarns can be made of staple fibres by several techniques. The method used is dependent upon such factors as the economic implications, the fibres to be used and desired properties of the yarn to be produced. Rings pinning is the oldest and most wide spread technique. Open end spinning is another major method. The development of short fibres, or staple, into yarn, when started in terms of basic manufacturing processes, is as follows:

Drafting
Twisting
Winding

Textile raw materials

As the fibres pass through these processes, they are successively formed into lap, sliver, roving and finally yarn. Here the manufacturing operation in which these stages occur:
  • Lap to card sliver by the carding process
  • Card sliver to comb sliver by the combing process (if the fibre is to be combed)
  • Sliver to roving by the drafting, or drawing process
  • Yarn reeled on bobbins, spools or cones by the winding process
Fabric
Fabric is a planar textile structure produces by interlacing yarns or filaments. Most fabrics are produced through knitting or weaving, but some are produced by non-woven processes such as braiding, felting, and twisting.

Weaving
A major method of fabric construction is weaving. The technique probably became known before spinning. Primitive people may have observed the interlaced grasses and twigs in the nests of birds, and thus discovered how they could make clothing for themselves. Spinning developed when people discovered that the raw materials could be improved before they were woven. In course of time, rude looms were made, which were crudely simple and hand-operated. The modern power loom used in the textile industry today essentially performs the same operations as the simple hand operated loom.

Knitting
Knitting is the second most frequently used method of fabric construction. The popularity of knitting has grown tremendously within recent years because of the increased versatility of techniques, the adaptability of the many new man-made fibres, and the growth in consumer demand for wrinkle resistant, stretchable, snug-fitting fabrics, particularly in the greatly expanding areas of sportswear and other casual wearing apparel. Today, the usage of knitted fabrics ranges from hosiery, underwear, sweaters, slacks, suits and coats, to rugs and other home furnishings.

Textile raw material

Some commercial names of fabric are as follows:
  • Aertex
  • Angora
  • Braid
  • Brocade
  • Chiffon
  • Canvas
  • Chambray
  • Denim
  • Fleece
  • Hopsack
Dyes
The dye is a complex compound which is applied in the textile materials represent color and contains chromophore and auxochrome groups in its chemical structure. It is necessary to know which dyes have an affinity for the vegetable, animal, or man-made fibres to select the proper dye for a fibre.

Textile raw materials

Different types of dyes are used in the textile industries as raw materials are as follows –
  • Basic dyes
  • Acid dyes
  • Mordant dyes
  • Substantive direct dyes
  • Developed dyes
  • Azoic dyes
  • Disperse dyes
  • Vat dyes
  • Reactive dyes
  • Pigment dyes
Chemicals and Auxiliaries
Dyeing chemicals and auxiliaries enables a processing operation in preparation, dyeing, printing or finishing to be carried out more effectively, or which is essential if a given effect is to be obtained.

Textile raw materials

Different types of chemicals and auxiliaries used in dyeing, printing and finishing are as follows –
  • Whitening agent
  • Wetting agent
  • Fixing agent
  • Detergent
  • Silicon
  • Stiffering agent
  • Water proofing agent
  • De-foaming agent
  • Enzymes
  • Caustic soda
  • Soda ash
  • Acetic acid
  • Oxalic acid

Friday, August 29, 2014

Hydraulic bursting tester

Principle

          The pressure in a liquid is exerted in all directions and this phenomenon of a liquid is used for testing bursting strength in hydraulic bursting strength tester.

Sample size

          The specimen for this test should be cut so that the sample is ½ inch greater in diameter of the clamp ring. Ten specimens are chosen avoiding inclusion of the same ends in the different specimens.
The instrument used for testing bursting strength should have a constant rate of speed and must be capable of giving a uniform displacement of 6 ± 0.25 cubic inches per minute. The clamp ring should have an internal diameter of 1.20 inches. For proper operation, the machine must be stopped at the instant of rupture in order to avoid additional application of pressure and load on the specimen.

Procedure

          Briefly, the specimen is clamped by a ring over a thin flexible rubber diaphragm which itself is clamped over a circular hole in the upper face of a reservoir. The liquid used may be water or glycerine. The pressure in the liquid is increased, by values or screw-driven position. Due to increase in the pressure, the diaphragm bulges, taking with it the specimen. At some point the fabric bursts and the pressure at that point is indicated by the pressure gauge.

Bursting tester
          Since the rubber diaphragm requires a certain pressure to stretch it, corrections are made by doing a blank test, i.e. noting the pressure required to distend the diaphragm the same amount without the presence of same fabric.
          In the test specimen, if cuts by chisel for ½ inch are made (either in warp or in weft direction or in both) or if a ¼ inch hole is punched and then the same test is carried out, then it is called as wounded bursting strength test.