Fiber

Fiber or fibre is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread. Fibers are of great importance in the biology of both plants and animals, for holding tissues together. Human uses for fibers are diverse. They can be spun into filaments, thread, string or rope. They can be used as a component of composite materials. They can also be matted into sheets to make products such as paper or felt. Fibers are often used in the manufacture of other materials.

Sources of natural fibers

Natural fibers include those made from plant, animal and mineral sources. Natural fibers can be classified according to their origin.

Vegetable fibers

Vegetable fibers are generally comprised mainly of cellulose: examples include cotton, linen, jute, flax, ramie, sisal, and hemp. Cellulose fibers serve in the manufacture of paper and cloth. This fiber can be further categorized into the following:

• Seed fiber: Fibers collected from seeds or seed cases. e.g. cotton and kapok.
• Leaf fiber: Fibers collected from leaves. e.g. sisal and agave.
• Bast fiber or skin fiber: Fibers are collected from the skin or bast surrounding the stem of their respective plant. These fibers have higher tensile strength than other fibers. Therefore, these fibers are used for durable yarn, fabric, packaging, and paper. Some examples are jute, kenaf, industrial hemp, ramie, rattan, soybean fiber, and even vine fibers and banana fibers.
• Fruit fiber: Fibers are collected from the fruit of the plant, e.g. coconut (coir) fiber.
• Stalk fiber: Fibers are actually the stalks of the plant. E.g. straws of wheat, rice, barley, and other crops including bamboo and grass. Tree wood is also such a fiber.

The most used natural fibers are cotton, flax and hemp, although sisal, jute, kenaf, and coconut are also widely used.

Animal fibers

Animal fibers generally comprise proteins; examples include silk, wool, angora, mohair and alpaca.

• Animal hair (wool or hairs): Fiber or wool taken from animals or hairy mammals. e.g. sheep's wool, goat hair (alpaca, Cashmere), horse hair, etc.
• Silk fiber: Fiber collected from dried saliva of bugs or insects during the preparation of cocoons. Examples include silk from silk worms.
• Avian fiber: Fibers from birds, e.g. feathers and feather fiber.

Mineral fibers

Mineral fibers are naturally occurring fiber or slightly modified fiber procured from minerals. These can be categorized into the following categories:

• Asbestos: The only naturally occurring mineral fiber. Variations are serpentine (chrysotile) and amphiboles (amorist, crocidolite, tremolite, actinolite, and anthophyllite).
• Ceramic fibers: Glass fibers (Glass wool and Quartz), aluminum oxide, silicon carbide, and boron carbide
• Metal fibers: Aluminum fibers

Man-made fibers

Man-made fibers may come from natural raw materials or from synthetic chemicals. Many types of fiber are manufactured 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 acetate.

Mineral fibers

The most well-known mineral fibers are glass and metal fibers.

• Fiberglas made from specific glass formulas and optical fiber, made from purified natural quartz, are also man-made fibers that come from natural raw materials.
• 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.
• Carbon fibers are often based on carbonized polymers, but the end product is pure carbon.

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:
  • polyamide nylon,
  • PET or PBT polyester
  • phenol-formaldehyde (PF)
  • polyvinyl alcohol fiber (PVOH)
  • polyvinyl chloride fiber (PVC)
  • polyolefins (PP and PE)
  • 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.
  • Aromatic polyamids such as Twaron, Kevlar and Nomex thermally degrade at high temperatures and do not melt. These fibers have strong bonding between polymer chains
  • polyethylene (PE), eventually with extremely long chains / HMPE (e.g. Dyneema or Spectra).
  • Elastomers can even be used, e.g. spandex although urethane fibers are starting to replace spandex technology.
  • polyurethane fiber                  Top of Page

• Coextruded 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 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 foil radar signals.

Microfibers

Micro fibers in textiles refer to sub-denier fiber (such as polyester drawn to 0.5 dn). Denier and Detex are two measurements of fiber yield based on weight and length. If the fiber density is known you also have a fiber diameter, otherwise it is simpler to measure diameters in micrometers. Microfibers in technical fibers refer to ultrafine fibers (glass or meltblown thermoplastic) often used in flirtation. Newer fiber designs include extruding fiber that splits into multiple finer fibers. Most synthetic fibers are round in cross-section, but special designs can be hollow, oval, star-shaped or tribunal. The latter design provides more optically reflective properties. Synthetic textile fibers are often crimped to provide bulk in a woven, nonwoven or knitted structure. Fiber surfaces can also be dull or bright. Dull surfaces reflect more light while bright tends to transmit light and make the fiber more transparent.

Very short and/or irregular fibers have been called fibrils. Natural cellulose, such as cotton or bleached kraft show smaller fibrils jutting out and away from the main fiber structure.

Cotton, wool, and man-made staple products are converted to yarn by a process called spinning. Upholstery fabric yarns are spun by three basic methods.

Spinning

Spinning is the process of creating yarn ,(or thread, rope, cable) from various raw fiber materials.

In spinning, separate fibers are twisted together to bind them into a stronger, long yarn. Characteristics of the yarn vary, based on the material used, fiber length and alignment, quantity of fiber used and degree of twist.here the old tools for spining Twist and ply

The direction in which the yarn is spun is called twist, and yarns are characterized as Z-twist or S-twist according to the direction of spinning (see diagram). Tightness of twist is measured in (twists per inch).Two or more spun yarns may be twisted together or plied to form a thicker yarn. Generally, handspun single plies are spun with a Z-twist, and plying is done with an S-twist.

  Z-twist and S-twist yarns.

Modern spinning

The modern spinning of textiles is a highly technical process and there are two common and very distinctly different methods. Convention ring spinning uses a continuous band (for want of a better term) of fibers which are unbroken during manufacture. By contrast open-end spinning depends on that continuous band being deliberately broken down into a stream of fibers. They are independant of one another usually in a stream of air. The great advantage of open-end spinning is that to insert twist into the yarn only the end of the yarn needs to be rotated. Whereas in conventional ring spinning the whole package of yarn must be rotated to insert twist. This limits the speed of ring spinning to a maximum of approximately 25,000rpm, whilst open-end machines are capable of in excess or 100,000rpm. However the downside is that open-end yarns are not as strong as ring spun yarns and the fabrics are not as soft handling and usually not as hard wearing - but they are less expensive.

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  In wrap spinning, a bundle of parallel fibers is wrapped in a spiraling fashion with other fibers. A bundle may contain 150-200 individual fibers along its length, yet not be thicker than a paper clip. Yarns spun by other methods are similar in size. Warp spinning is suitable for making strong, dense yarns.
  
  

OPEN END SPINNING

• With open end spinning the yarn has individual fibers that are not arranged as uniformly as in wrap or ring spun yarns. Most of the fibers are generally parallel, but with lots of crisscrossing, while some fiber irregularly wraps around the main bundle.
  

Weaving is an ancient textile art and craft that involves placing two sets of threads or yarn called the warp and weft of the loom and turning them into cloth.

Process

An Indian weaver preparing his warp.

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In general, weaving involves the interlacing of two sets of threads at right angles to each other: the warp and the weft. The warp are held taut and in parallel order, typically by means of a loom, though some forms of weaving may use other methods.

Woven 

fabrics are constructed for durability and stability on quality by three processes: Weaving, Tufting and Knitting

Woven fabrics interlace yarns essentially at right angles. In velvet wovens, the plush pile is locked in by an interlocking system as shown here.