Fiber refers to ropes or strings used in composite materials or matted into sheets like paper or felt. There are natural fibers from plants, animals, and geology as well as man-made fibers whose chemical composition is modified. Natural fibers are biodegradable while man-made fibers include regenerated fibers from natural sources and completely synthetic fibers. Fibers can be made from materials like carbon, glass, metal, polymers, and minerals and are classified by their origin and properties.

1. Fiber
.
Fiber or fibre (see spelling differences; from the French fibre[1]
) is a rope or string used as a component
of composite materials, or matted[disambiguation needed]
into sheets to make products such as paper or felt.
Fibers are often used in the manufacture of other materials. The strongest engineering materials are
generally made as fibers, for example carbon fiber and Ultra-high-molecular-weight polyethylene.
Synthetic fibers can often be produced very cheaply and in large amounts compared to natural fibers, but
for clothing natural fibers can give some benefits, such as comfort, over their synthetic counterparts.
Textile fiber
A unit in which many complicated textile structures are built up is said to be textile fiber.
Natural fibers
Main article: Natural fiber
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, sisal and bagasse. Plant fibers are employed in the
manufacture of paper and textile (cloth), and dietary fiber is an important component of human
nutrition.
 Wood fiber, distinguished from vegetable fiber, is from tree sources. Forms include groundwood,
thermomechanical pulp (TMP) and bleached or unbleached kraft or sulfite pulps. Kraft and
sulfite, also called sulphite, refer to the type of pulping process used to remove the lignin bonding
the original wood structure, thus freeing the fibers for use in paper and engineered wood products
such as fiberboard.
 Animal fibers consist largely of particular proteins. Instances are silkworm silk, spider silk,
sinew, catgut, wool, sea silk and hair such as cashmere wool, mohair and angora, fur such as
sheepskin, rabbit, mink, fox, beaver, etc.
 Mineral fibers include the asbestos group. Asbestos is the only naturally occurring long mineral
fiber. Six minerals have been classified as "asbestos" including chrysotile of the serpentine class
and those belonging to the amphibole class: amosite, crocidolite, tremolite, anthophyllite and
actinolite. Short, fiber-like minerals include wollastonite and palygorskite.
Man-made fibers
Man-made fibers or chemical fibers are fibers whose chemical composition, structure, and properties are
significantly modified during the manufacturing process.[2]
Man-made fibers consist of regenerated fibers
and synthetic fibers.
Regenerated fibers
Regenerated fibers are manufactured from natural sources,including modal, and Lyocell.
Cellulose regenerated fibers
Cellulose fibers are a subset of man-made fibers, regenerated from natural cellulose. The cellulose comes
from various sources. Modal is made from beech trees, bamboo fiber is a cellulose fiber made from
bamboo, seacellis made from seaweed,etc.
Semi-synthetic fibers
Semi-synthetic fibers are made from raw materials with naturally long-chain polymer structure and are
only modified and partially degraded by chemical processes,in contrast to completely synthetic fibers
such as nylon (polyamide) or dacron (polyester), which the chemist synthesizes from low-molecular
weight compounds by polymerization (chain-building) reactions. The first semi-synthetic fiber is rayon.[3]
Cellulose semi-synthetic fibers
Some examples are:
 rayon
 diacetate fiber
 triacetate fiber.

2. Synthetic fibers
Main article: Synthetic fiber
Synthetic come entirely from synthetic materials such as petrochemicals, unlike those man-made fibers
derived from such natural substances as cellulose or protein.[4]
Fiber classification in reinforced plastics falls into two classes:(i) short fibers, also known as
discontinuous fibers, with a general aspect ratio (defined as the ratio of fiber length to diameter) between
20 to 60, and (ii) long fibers, also known as continuous fibers, the generalaspect ratio is between 200 to
500.[5]
Metallic fibers
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. See also Stainless steelfibers.
Carbon fiber
Carbon fibers are often based on oxydized and via pyrolysis carbonized polymers like PAN,but the end
product is almost pure carbon.
Silicon carbide fiber
Silicon carbide fibers, where the basic polymers are not hydrocarbons but polymers, where about 50% of
the carbon atoms are replaced by silicon atoms, so-called poly-carbo-silanes. The pyrolysis yields an
amorphous silicon carbide, including mostly other elements like oxygen, titanium, or aluminium, but with
mechanical properties very similar to those of carbon fibers.
Fiberglass
Fiberglass, made from specific glass, and optical fiber, made from purified natural quartz, are also man-
made fibers that come from natural raw materials, silica fiber, made from sodium silicate (water glass)
and basalt fiber made from melted basalt.
Mineral fibers
Mineral fibers can be particularly strong because they are formed with a low number of surface defects,
asbestos is a common one.[6]
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. These fibers are made from:
o polyamide nylon
o PET or PBT polyester
o phenol-formaldehyde (PF)
o polyvinyl chloride fiber (PVC) vinyon
o polyolefins (PP and PE) olefin fiber
o acrylic polyesters, pure polyester 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 Elastolefin
 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 RF deflection for radar chaff.

3. 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.
Microfibers
Microfibers 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 ultra fine fibers (glass or meltblown thermoplastics) often used in filtration. 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 trilobal. The latter design provides
more optically reflective properties. Synthetic textile fibers are often crimped to provide bulk in a woven,
non woven 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
References-
1. http://en.wikipedia.org/wiki/Fiber
2. Fiber to Fabric- BernardP. Corbman (Author)