Fibers -units of matter characterized by flexibility, fineness and high ratio of length to thickness. Other necessary attribute for textiles are adequate strength and resistance to conditions encountered during wears, as well as absence of undesirable colour, and finally the property of dye ability.
In generally, the steps in the manufacture of fabrics from raw material to finished goods are as follows:
· Fibre, which is either spun (or twisted) into yarn or else directly compressed into fabric.
· Yarn, which is woven, knitted, or otherwise made into fabric.
· Fabric, which by various dyeing and finishing processed becomes consumers goods.
- Classification of textile fibers
According to the nature and origin different textile fibers can be classified as follows:
Natural fibers include those produced by plants, animals, and geological processes. They are biodegradable over time. They can be classified according to their origin:
- Vegetable fibers are generally based on arrangements of cellulose, often with lignin: examples include cotton, hemp, jute, flax, ramie, and sisal.
- Animal fibers consist largely of particular proteins. Instances are spider silk, sinew, catgut, wool and hair such as cashmere, mohair and angora, fur such as sheepskin, rabbit, mink, fox, beaver, etc.
- Mineral fibers comprise asbestos. Asbestos is the only naturally occurring long mineral fiber. Short, fiber-like minerals include wollastinite, attapulgite and halloysite
- Manmade fibers
- Polymer fibers
Polymer fibers are a subset of man-made fibers, which are based on synthetic chemicals (often from petrochemical sources) rather than arising from natural materials by a purely physical process. Such fibers are made from:
o polyamide nylon,
o PET or PBT polyester
o phenol-formaldehyde (PF)
o polyvinyl alcohol fiber (PVOH)
o polyvinyl chloride fiber (PVC)
o polyolefins (PP and PE)
o acrylic polymers, pure polyacrylonitrile PAN fibers are used to make carbon fiber by roasting them in a low oxygen environment. Traditional acrylic fiber is used more often as a synthetic replacement for wool. Carbon fibers and PF fibers are noted as two resin-based fibers that are not thermoplastic, most others can be melted.
o Aromatic polyamids (aramids) such as Twaron, Kevlar and Nomex thermally degrade at high temperatures and do not melt. These fibers have strong bonding between polymer chains
o polyethylene (PE), eventually with extremely long chains / HMPE (e.g. Dyneema or Spectra).
o Elastomers can even be used, e.g. spandex although urethane fibers are starting to replace spandex technology.
o polyurethane fiber
o Co-extruded fibers have two distinct polymers forming the fiber, usually as a core-sheath or side-by-side. Coated fibers exist such
as nickel-coated to provide static elimination, silver-coated to provide anti-bacterial properties and aluminum-coated to provide RF deflection for radar chaff. Radar chaff is actually a spool of continuous glass tow that has been aluminum coated. An aircraft-mounted high speed cutter chops it up as it spews from a moving aircraft to confuse radar signals.
2. Regunrated fibers
Regunrated fibers are the fibers produced from natural cellulose, including rayon, modal, and the more recently developed Lyocell. Cellulose-based fibers are of two types, regenerated or pure cellulose such as from the cupro-ammonium process and modified or derivitized cellulose such as the cellulose acetates.
(b). Inorganic fibers
- Mineral fibers
o Glass fiber, made from specific glass, and optical fiber, made from purified natural quartz, are also man-made fibers that come from natural raw materials.
o Metallic fibers can be drawn from ductile metals such as copper, gold or silver and extruded or deposited from more brittle ones, such as nickel, aluminum or iron.
o Carbon fibers are often based on carbonised polymers, but the end product is pure carbon.