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Friday, February 9, 2018

Textile Fibers and Their Classification

Application of fibers in textiles and clothing starts from the development of human evolution. Clothing became existence, not for aesthetic purpose or decoration but for protection against cold, hot, rain, dust, etc. initially. Application of fibers in clothing dates back to 5000–4500 BC with utilization of hemp, flax, cotton, silk and later sericulture. Till Industrial Revolution, all the source of fiber is from nature. 18th and 19th centuries witnessed an era of industrial revolution along with machineries for fiber processing and application. Gradually with the introduction of regenerated fibers like rayon and later on synthetic fibers like nylon and polyester reduced monopoly of natural fibers. It also created a competition for new and unique fibers and fiber development.

The concept of regenerated and synthetic fibers induced a new dimension to the research activity to develop new fibers. It created a strong philosophy that from any material fiber can be developed, manufactured or regenerated provided the chemical behavior and structure, the structural alignment, molecular properties and the processing conditions can be analyzed and controlled. This means that there will be a wide range of fibers and equally a wide range of materials to be developed as fibers.

Textile fiber is the basic and principle raw materials to produce various types of textile finished products. A fiber that can be spun into yarn or processed into textile such as a woven fabric, knit fabric, lace, felt, non-woven etc by means of an appropriate interlacing method is called as textile fiber.

Classification of Textile Fibers:
Generally textile fibers can be classified into main two types they are-Natural fiber And Synthetic fiber or manmade fiber or artificial fiber. Textile fibers can also be classified in the following ways:
  1. Classification of textile fibers based on sources
  2. Classification of textile fibres based on polymer
Classification of Textile Fibers Based on Sources:
With this concept, the classification of fiber was established as per its source and it is mentioned in Fig.-1. The major natural fibers present around us from vegetable and natural sources. There are around 15 important natural fibers available for processing and conversion into fabrics. Those are discussed below.

Classification of textile fibers as per sources
Figure-1: Classification of textile fibers as per sources
Vegetable sources:
Major fibers from vegetable sources are discussed below:

  • Cotton: Cotton is most widely used natural fiber and consists of pure cellulose. It is produced in China, Brazil, India, Pakistan, USA and Uzbekistan.
  • Flax: Flax is a lignocellulosic bast fiber, mostly present in European Union. This fiber is mostly used to make linen.
  • Hemp: Hemp is also a lignocellulosic bast fiber with low quantity of lignin. The world’s leading producer of hemp fiber is China.
  • Jute: Jute is the strongest vegetable fiber from India and Bangladesh. It is also a lignocellulosic fiber.
  • Ramie: Ramie is also a lignocellulosic bast fibre mostly available in China and Brazil. It is also known as China grass, with a silky lustre and better elasticity.
  • Sisal: Sisal is a hard and coarser leaf fiber, mostly available in Brazil, Tanzania and Kenya.
  • Abaca: Abaca is a leaf fiber, also known as manila hemp, extracted from leaf sheath around the trunk of Musa textiles. The world’s major fi bre producer is Philippines. Lignin content in the fibre is about 15%.
  • Coir: Coir is a hard, short and coarse fiber extracted from the shells of coconut. It is mostly present in India, Sri Lanka, Philippines, Vietnam, Indonesia and Brazil. This fibre contains highest amount of lignin making it stronger but less flexible.
Animal sources:
Major fibres from animal sources are discussed below:

  • Alpaca: Alpaca is a hair fiber like wool, comes from the Lama Pocos. This fibre comes in approximately 22 natural colors, produced mostly in Peru, North America, Australia and New Zealand. It is stronger than wool fiber.
  • Angora: Angora is a rabbit fiber, very soft, fine and silky. 90% of the fiber is produced in China. Angora fabric is very suitable for thermal clothing.
  • Camel hair: Camel hair is available from the two humped Bactrian camel mostly present with nomadic households in Mongolia and inner Mongolia, China. It is the softest and more premium hair fibre.
  • Cashmere fiber: Cashmere fiber is available with Kashmir goats, in China, Australia, India, Pakistan, New Zealand, Turkey and USA. It is a luxurious and expensive fiber.
  • Mohair fiber: Mohair fiber is produced from Angora goat, available in South Africa. It is a smooth and lustrous fiber.
  • Silk: Silk is the natural filament fiber, with high lustre, mostly produced in China, Brazil, India, Thailand and Vietnam.
  • Wool: Wool is the most important protein fiber. It is the first domesticated fiber, mostly produced in Australia, New Zealand, China, Iran, Argentina and UK.
Ground and petrochemical sources:
In addition to the collection of the fibers from the sources above the ground, there are fibers from below the ground like metals. From World War II, there has been a thrust to produce synthetic materials, mostly derived from petrochemicals. The manufactured fibre is termed as ‘synthetic fibers’ as the raw materials were available by synthesis followed by polymerization and fiber formation. Synthetic fibers became the consequence of spectacular growth in petrochemicals development and utilization. The growth in the development of synthetic fibres and synthetic fiber industry along with polymer industry became phenomenal with the growth of petrochemical industry.

Classification of Textile Fibres Based on Polymer:
Polymer is a material constructed of smaller molecules of the same substance that form larger molecules. The polymers are any of numerous natural and synthetic compounds of usually high molecular weight and consisting of up to millions of repeated linked units, each a relatively light and simple molecule.

The term is derived from the Greek words: ‘polumeres’, where polus meaning many, and meros meaning parts. A key feature that distinguishes polymers from other molecules is the repetition of many identical, similar or complementary molecular subunits in these chains.

Polymers, macromolecules, high polymers and giant molecules are basically same and consist of high-molecular-weight materials composed of these repeating subunits. These materials may be organic, inorganic or organometallic, and synthetic or natural in origin. Polymers are essential materials for almost every industry such as adhesives, building materials, paper, cloths, fibers, coatings, plastics, ceramics, concretes, liquid crystals, photo resists and coatings.

These polymers can be natural or synthetic and organic or inorganic. Organic polymers are distinguished from inorganic polymers because of presence of carbon atom in the main chain. Presence of totally carbon atoms termed as carbochain polymers. If the main chain consists of other atoms with carbon, then it is termed as heterochain polymers. Natural inorganic polymers include sand, asbestos, agates, feldspars, mica, quartz and talc.

Natural organic polymers include polysaccharides or polycarbohydrates such as starch and cellulose, nucleic acids, lignin, rubber and proteins. Synthetic inorganic polymers include boron nitride, concrete, many high-temperature superconductors and a number of glasses. Synthetic organic polymers include fibers, plastics and coatings, such as polyethylene, polypropylene, polyamides, polyesters, vinyl polymers, polyurethanes and synthetic rubbers.

Fibers are polymeric materials that are strong in one direction, and they are much longer (>100 times) than their width. This is termed as l/d ratio. Elastomers or rubbers are polymeric materials that can be distorted through the application of force, and when the force is removed, the material returns to its original shape. Plastics are materials that have properties between fibers and elastomers—they are hard and flexible.

The resources for natural fibers are also natural high molecular weight polymeric substances. This means that both natural and synthetic fibers are polymeric materials. Based on the polymeric materials present in fibers, all fibers can also be classified in the way, shown in Fig-2.

Classification of textile fibers based on the polymer.
Figure-2: Classification of textile fibers based on the polymer