Fiber or fibre (from links=no
) is a natural or man-made substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate fibers, for example Carbon fibers 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.
Natural fibers develop or occur in the fiber shape, and include those produced by plants, animals, and geological processes.
They can be classified according to their origin:
fiber crop are generally based on arrangements of cellulose, often with lignin: examples include cotton, Cannabis sativa, jute, flax, abaca, piña, ramie, sisal, bagasse, and banana. Plant fibers are employed in the manufacture of paper and textile (cloth), and dietary fiber is an important component of human nutrition.
Wood fibre, distinguished from vegetable fiber, is from tree sources. Forms include groundwood, Lagetta lagetto, thermomechanical pulp (TMP), and bleached or unbleached Kraft process or sulfite pulps. Kraft and sulfite 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.
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 wool, fur such as sheepskin, rabbit, mink, fox, beaver, etc.
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 group class and those belonging to the amphibole class: amosite, crocidolite, tremolite, anthophyllite and actinolite. Short, fiber-like minerals include wollastonite and palygorskite.
Biological fibers also known as fibrous proteins or consist largely of biologically relevant and biologically very important proteins, mutations or other genetic defects can lead to severe diseases. Instances are collagen
family of proteins, tendon, muscle proteins like actin, cell proteins like and many others, spider silk, sinew and hair etc.
Man-made or chemical fibers are fibers whose chemical composition, structure, and properties are significantly modified during the manufacturing process.
Man-made fibers consist of regenerated fibers and 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 earliest semi-synthetic fiber is the cellulose regenerated fiber, rayon
Most semi-synthetic fibers are cellulose regenerated fibers.
Cellulose regenerated fibers
are a subset of man-made fibers, regenerated from natural cellulose
. The cellulose comes from various sources: rayon from tree wood fiber, bamboo fiber
from bamboo, seacell
, etc. In the production of these fibers, the cellulose is reduced to a fairly pure form as a viscous mass and formed into fibers by extrusion through spinnerets. Therefore, the manufacturing process leaves few characteristics distinctive of the natural source material in the finished products.
Some examples of this fiber type are:
Historically, cellulose diacetate and -triacetate were classified under the term rayon, but are now considered distinct materials.
come entirely from synthetic materials such as
, unlike those man-made fibers derived from such natural substances as cellulose or protein.
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 and 60, and (ii) long fibers, also known as continuous fibers, the general aspect ratio is between 200 and 500.
[Serope Kalpakjian, Steven R Schmid. "Manufacturing Engineering and Technology". International edition. 4th Ed. Prentice Hall, Inc. 2001. .]
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 steel fibers.
Carbon fibers are often based on oxidized and via pyrolysis
carbonized polymers like PAN, but the end product is almost pure carbon.
Silicon carbide fiber
fibers, where the basic polymers are not
but polymers, where about 50% of the carbon atoms are replaced by silicon atoms, so-called poly-carbo-
. 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.
, 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 can be particularly strong because they are formed with a low number of surface defects, asbestos
is a common one.
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:
PET or PBT polyester
polyvinyl chloride fiber (PVC) vinyon
polyolefins (PP and PE) olefin fiber
Acrylic fiber 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.
aramid (aramids) 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).
can even be used, e.g. spandex although urethane fibers are starting to replace spandex technology.
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. 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.
refer to sub-denier fiber (such as polyester
drawn to 0.5 denier). Denier and Dtex 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.
[Hans-J. Koslowski. "Man-Made Fibers Dictionary". Second edition. Deutscher Fachverlag. 2009 ]
Typical properties of selected fibers
Fibers can be divided into natural and man-made (synthetic) substance, their properties can affect their performance in many applications. Nowadays, man-made fiber materials are replacing other conventional materials like glass and wood in a number of applications.
This is because man-made fibers can be engineered chemically, physically, and mechanically to suit particular technical engineering.
In choosing a fiber type, a manufacturer would balance their properties with the technical requirements of the applications. Various fibers are available to select for manufacturing. Here are typical properties of the sample natural fibers as compared to the properties of man-made fibers.
|+Table 1. Typical Properties of Selected Natural Fibers||Fiber type||Fiber Diameter
|Specific Gravity||Tensile Strength
|Elongation at Break
|Sugar Cane Bagasse||0.008-0.016||1.2-1.3||26.7-42||2175-2750||1.1||70-75|
|a Adapted from ACI 544. IR-96 P58, reference 12 P240 and 13
b N/A means properties not readily available or not applicable
|+Table 2. Properties of Selected Man-made Fibers||Fiber type||Fiber Diameter
|Specific Gravity||Tensile Strength (Ksi)||Elasticity Modulus
|Elongation at Break
|a Adapted from ACI 544. IR-96 P40, reference 12 P240, 11 P209 and 13
b N/A means properties not readily available or not applicable
The tables above just show typical properties of fibers, in fact there are more properties which could be referred as follows (from a to z):
Arc Resistance, Biodegradation, Coefficient of Linear Thermal Expansion, Continuous Service Temperature, Density, Ductility / Brittleness Transition Temperature, Elongation at Break, Elongation at Yield, Fire Resistance, Flexibility, Gamma Radiation Resistance, Gloss, Glass transition, Hardness, Heat Deflection Temperature, Shrinkage, Stiffness, Ultimate tensile strength, Thermal Insulation, Toughness, Transparency, UV Light Resistance, Volume Resistivity, Water absorption, Young's Modulus