Difference Between FRP and GRP

Difference Between FRP and GRP

Nov 17th, 2012 | By admin

FRP vs GRP

In modern engineering, materials play a vital role defining the design, structure, performance, and efficiency of the product. Sometimes, the naturally occurring engineering materials are not able to satisfy the specifications of a product. Therefore, new materials were developed to accommodate a wide variety of engineering requirements by combining two or more materials together. These are known as composite materials.

Concrete, plywood, Aerogel, and carbon fibre are reinforced polymers; all are composite materials. This article focuses on a specific class of composite materials, which are known as fibre reinforced polymers. These materials are light weight, strong, and robust.

What is Fibre Reinforced Plastic/Polymer (FRP)?Fibre reinforced polymers are made of two primary constituents; fibres and a polymer matrix. In FRP, the fibre is embedded in a polymer matrix. This structure gives completely different chemical and physical properties than the properties of the individual materials. In fact, these materials satisfy higher engineering requirements than the ordinary materials. Hence composites are applied in less sophisticated to very sophisticate and demanding manufacturing tasks. Mechanical, civil, biomedical, marine, and the aerospace industries are main users of composite materials.

The primary role of fibres is to provide strength and stiffness to the material. But the fibre alone is brittle (ex: glass). Therefore, the fibres are encased in a coating of polymer materials. Polymer matrix holds the fibres in their position and transfers the loads between the fibres. It also contributes to the inter-laminar shear strength.

The fibres used in composite are as follows; E-glass, S-glass, Quartz, Aramid (Kevlar 49), Spectra 1000, Carbon (AS4), Carbon (IM-7), Graphite (P-100), and Boron. Polyesters, Vinyl Esters, Epoxies, Bismaleimides, Polyimides, and Phenolics are the polymers used. Each polymer has different chemical and physical properties; therefore, contribute differently to the composite structure. As a result, the composite properties are also different based on the polymer.

Polyester and vinyl are low cost materials, hence used extensively in commercial applications. Epoxies are used for high performance continuous fibre matrices. It also performs better than vinyl and polyester in high temperature conditions. Bismaleimides and Polyimides are high temperature resin matrices for use in temperature critical engineering applications. Phenolics are high temperature resin systems with a good smoke and fire resistance; therefore, used in aircraft interiors.

What is Glass Reinforced Plastic (GRP) / Glass Fibre Reinforced Plastic (GFRP)?Glass Reinforced Plastic, commonly known as fiberglass, is a fibre reinforced polymer with glass fibres in the composite structure. The polymer is usually the epoxy, polyester, or the vinyl. Fibreglass materials are commonly used in high performance leisure aircrafts and gliders, boats, automobiles, bathtubs, hot tubs, water tanks, roofing products, pipes, cladding, cast, Surfboards, and external door skins.

What is the difference between FRP and GRP? FRP is a composite material, where high strength fibres are included in a polymer matrix. They are used in many commercial and engineering applications due to their high strength and light weight. FRP is widely used as a substitute for metal and wood. Best example is the use of carbon fibre reinforced polymer (CFRP) instead of aluminum and titanium or high grade steel in aircrafts.

Fibreglass or GRP is a composite material made out of glass fibres and uses polyester, vinyl, or epoxy as the polymer. It is used to make gliders, boats, and bathtubs. Fibreglass is used mainly for commercial applications. Fibre glass is one type of FRP.

Re: Difference Between GRP and FRP

03/31/2011 2:37 AM

Hi All,

Glass-reinforced plasticGlass-reinforced plastic (GRP),[1] also known as glass fiber-reinforced plastic (GFRP),[2] is a fiber reinforced polymer made of a plastic matrix reinforced by fine fibers made of glass. It is also known as GFK (for Glasfaserverstrkter Kunststoff), or simply by the name of the reinforcing fibers themselves: fiberglass.

GRP is a lightweight, strong material with very many uses, including boats, automobiles, water tanks, roofing, pipes and cladding.

The plastic matrix may be epoxy, a thermosetting plastic (most often polyester or vinylester) or thermoplastic.

Fibre Reinforced Plastics (FRP) Fibre-reinforced polymers/plastics is a recently developed material for strengthening of RC and masonry structure. This is an advanced material and most of the development in its application in structural retrofitting has taken place in the last two decades. It has been found to be a replacement of steel plate bonding and is very effective in strengthening of columns by exterior wrapping. The main advantage of FRP is its high strength to weight ratio and high corrosion resistance. FRP plates can be 2 to 10 times stronger than steel plates, while their weight is just 20% of that of steel. However, at present, their cost is high. FRP composites are formed by embedding a continuous fibre matrix in a resin matrix. The resin matrix binds the fibre together and also provides bond between concrete and FRP.

The commonly used fibres are Carbon fibres, Glass fibres and Aramid fibres and the commonly used resins are polyester, vinyl ester and epoxy. FRP is named after the fibre used, e.g. Carbon Fibre Reinforced Polymer (CFRP), Glass Fibre Reinforced Polymer (GFRP), and Aramid Fibre Reinforced Polymer (AFRP).

The fibres are available in two forms

(i) Unidirectional tow sheet, and

(ii) (ii) Woven fabric.

The application of resin can be in-situ or in the form of prefabrication of FRP plates and other shapes by pultrusion. The in-situ application is by wet lay-up of a woven fabric or tow plate immersed in resin. This method is more versatile as it can be used on any shape. On the other hand, prefabrication results in better quality control. The manufacturers supply these materials as a package and each brand has specific method of application, which is to be followed carefully. Specialized firms have developed in India also, which take up the complete execution work and supply of material. It is important to note the difference between the properties of steel and FRP and it should be understood that FRP cannot be treated as reinforcement in conventional RC design methods

Fiberglass (or fibreglass) (also called glass-reinforced plastic, GRP,[1] glass-fiber reinforced plastic, or GFRP[2]) is a fiber reinforced polymer made of a plastic matrix reinforced by fine fibers of glass. It is also known as GFK (for German: Glasfaserverstrkter Kunststoff).

Fiberglass is a lightweight, extremely strong, and robust material. Although strength properties are somewhat lower than carbon fiber and it is less stiff, the material is typically far less brittle, and the raw materials are much less expensive. Its bulk strength and weight properties are also very favorable when compared to metals, and it can be easily formed using molding processes.

The plastic matrix may be epoxy, a thermosetting plastic (most often polyester or vinylester) or thermoplastic.

Common uses of fiberglass include high performance aircraft (gliders), boats, automobiles, baths, hot tubs, water tanks, roofing, pipes, cladding, casts, surfboards and external door skins.

Contents

1 Fiber

1.1 Production 1.2 Sizing 2 Properties 3 Applications

3.1 Storage tanks 3.2 House building 3.3 Piping 4 Construction methods

4.1 Fiberglass hand lay-up operation 4.2 Fiberglass spray lay-up operation 4.3 Pultrusion operation 4.4 Chopped strand mat 5 Warping 6 Health problems 7 Examples of fiberglass use 8 See also 9 ReferencesFiber

Glass reinforcements used for fiberglass are supplied in different physical forms, microspheres, chopped or woven.

Unlike glass fibers used for insulation, for the final structure to be strong, the fiber's surfaces must be almost entirely free of defects, as this permits the fibers to reach gigapascal tensile strengths. If a bulk piece of glass were to be defect free, then it would be equally as strong as glass fibers; however, it is generally impractical to produce bulk material in a defect-free state outside of laboratory conditions.[3]ProductionThe manufacturing process for glass fibers suitable for reinforcement uses large furnaces to gradually melt the silica sand, limestone, kaolin clay, fluorspar, colemanite, dolomite and other minerals to liquid form. Then it is extruded through bushings, which are bundles of very small orifices (typically 525 micrometres in diameter for E-Glass, 9 micrometres for S-Glass). These filaments are then sized (coated) with a chemical solution. The individual filaments are now bundled together in large numbers to provide a roving. The diameter of the filaments, as well as the number of filaments in the roving determine its weight. This is typically expressed in yield-yards per pound (how many yards of fiber in one pound of material, thus a smaller number means a heavier roving, example of standard yields are 225yield, 450yield, 675yield) or in tex-grams per km (how many grams 1km of roving weighs, this is inverted from yield, thus a smaller number means a lighter roving, examples of standard tex are 750tex, 1100tex, 2200tex).

These rovings are then either used directly in a composite application such as pultrusion, filament winding (pipe), gun roving (automated gun chops the glass into short lengths and drops it into a jet of resin, projected onto the surface of a mold), or used in an intermediary step, to manufacture fabrics such as chopped strand mat (CSM) (made of randomly oriented small cut lengths of fiber all bonded together), woven fabrics, knit fabrics or uni-directional fabrics.

SizingA sort of coating, or primer, is used which both helps protect the glass filaments for processing/manipulation as well as ensure proper bonding to the resin matrix, thus allowing for transfer of shear loads from the glass fibers to the thermoset plastic. Without this bonding, the fibers can 'slip' in the matrix and localised failure would ensue.[citation needed].

PropertiesAn individual structural glass fiber is both stiff and strong in tension and compressionthat is, along its axis. Although it might be assumed that the fiber is weak in compression, it is actually only the long aspect ratio of the fiber which makes it seem so; i.e., because a typical fiber is long and narrow, it buckles easily.[3] On the other hand, the glass fiber is weak in shearthat is, across its axis. Therefore if a collection of fibers can be arranged permanently in a preferred direction within a material, and if the fibers can be prevented from buckling in compression, then that material will become preferentially strong in that direction.

Furthermore, by laying multiple layers of fiber on top of one another, with each layer oriented in various preferred directions, the stiffness and strength properties of the overall material can be controlled in an efficient manner. In the case of fiberglass, it is the plastic matrix which permanently constrains the structural glass fibers to directions chosen by the designer. With chopped strand mat, this directionality is essentially an entire two dimensional plane; with woven fabrics or unidirectional layers, directionality of stiffness and strength can be more precisely controlled within the plane.

A fiberglass component is typically of a thin "shell" construction, sometimes filled on the inside with structural foam, as in the case of surfboards. The component may be of nearly arbitrary shape, limited only by the complexity and tolerances of the mold used for manufacturing the shell.

MaterialSpecific gravityTensile strength MPa (ksi)Compressive strength MPa (ksi)

Polyester resin (Not reinforced)[4]1.2855 (7.98)140 (20.3)

Polyester and Chopped Strand Mat Laminate 30% E-glass[4]1.4100 (14.5)150 (21.8)

Polyester and Woven Rovings Laminate 45% E-glass[4]1.6250 (36.3)150 (21.8)

Polyester and Satin Weave Cloth Laminate 55% E-glass[4]1.7300 (43.5)250 (36.3)

Polyester and Continuous Rovings Laminate 70% E-glass[4]1.9800 (116)350 (50.8)

E-Glass Epoxy composite[5]1.991,770 (257)

S-Glass Epoxy composite[5]1.952,358 (342)

ApplicationsFiberglass is an immensely versatile material which combines its light weight with an inherent strength to provide a weather resistant finish, with a variety of surface textures.

The development of fiber-reinforced plastic for commercial use was being extensively researched in the 1930s. It was particularly of interest to the aviation industry. Mass production of glass strands was accidentally discovered in 1932 when a researcher at the Owens-Illinois directed a jet of compressed air at a stream of molten glass and produced fibers. Owens joined up with the Corning company in 1935 and the method was adapted by Owens Corning to produce its patented "Fiberglas" (one "s"). A suitable resin for combining the "Fiberglas" with a plastic was developed in 1936 by du Pont. The first ancestor of modern polyester resins is Cyanamid's of 1942. Peroxide curing systems were used by then.

During World War II, fiberglass was developed as a replacement for the molded plywood used in aircraft radomes (fiberglass being transparent to microwaves). Its first main civilian application was for building of boats and sports-car bodies, where it gained acceptance in the 1950s. Its use has broadened to the automotive and sport equipment sectors as well as aircraft, although its use there is now partly being taken over by carbon fiber which weighs less per given volume and is stronger both by volume and by weight. Fiberglass uses also include hot tubs, pipes for drinking water and sewers, office plant display containers and flat roof systems.

Advanced manufacturing techniques such as pre-pregs and fiber rovings extend the applications and the tensile strength possible with fiber-reinforced plastics.

Fiberglass is also used in the telecommunications industry for shrouding the visual appearance of antennas, due to its RF permeability and low signal attenuation properties. It may also be used to shroud the visual appearance of other equipment where no signal permeability is required, such as equipment cabinets and steel support structures, due to the ease with which it can be molded, manufactured and painted to custom designs, to blend in with existing structures or brickwork. Other uses include sheet form made electrical insulators and other structural components commonly found in the power industries.

Because of fiberglass's light weight and durability, it is often used in protective equipment, such as helmets. Many sports use fiberglass protective gear, such as modern goaltender masks and newer baseball catcher's masks.

Storage tanks

Several large fiberglass tanks at an airport

Storage tanks can be made of fiberglass with capacities up to about 300 tonnes. The smaller tanks can be made with chopped strand mat cast over a thermoplastic inner tank which acts as a preform during construction. Much more reliable tanks are made using woven mat or filament wound fibre with the fibre orientation at right angles to the hoop stress imposed in the side wall by the contents. They tend to be used for chemical storage because the plastic liner (often polypropylene) is resistant to a wide range of strong chemicals. Fiberglass tanks are also used for septic tanks.

House building

A fiberglass dome house in Davis, CaliforniaGlass reinforced plastics are also used in the house building market for the production of roofing laminate, door surrounds, over-door canopies, window canopies and dormers, chimneys, coping systems, heads with keystones and sills. The use of fiberglass for these applications provides for a much faster installation and due to the reduced weight manual handling issues are reduced. With the advent of high volume manufacturing processes it is possible to construct fiberglass brick effect panels which can be used in the construction of composite housing. These panels can be constructed with the appropriate insulation which reduces heat loss.

PipingGRP and GRE pipe systems can be used for a variety of applications, above and under the ground.

Firewater systems

Cooling water systems

Drinking water systems

Waste water systems/Sewage systems

Gas systems

Construction methodsFiberglass hand lay-up operationA release agent, usually in either wax or liquid form, is applied to the chosen mold. This will allow the finished product to be removed cleanly from the mold. Resintypically a 2-part polyester, vinyl or epoxyis mixed with its hardener and applied to the surface. Sheets of fibreglass matting are laid into the mold, then more resin mixture is added using a brush or roller. The material must conform to the mold, and air must not be trapped between the fiberglass and the mold. Additional resin is applied and possibly additional sheets of fiberglass. Hand pressure, vacuum or rollers are used to make sure the resin saturates and fully wets all layers, and any air pockets are removed. The work must be done quickly enough to complete the job before the resin starts to cure, unless high temperature resins are used which will not cure until the part is warmed in an oven.[6] In some cases, the work is covered with plastic sheets and vacuum is drawn on the work to remove air bubbles and press the fiberglass to the shape of the mold.[7]Fiberglass spray lay-up operationThe fiberglass spray lay-up process is similar to the hand lay-up process but the difference comes from the application of the fiber and resin material to the mold. Spray-up is an open-molding composites fabrication process where resin and reinforcements are sprayed onto a mold. The resin and glass may be applied separately or simultaneously "chopped" in a combined stream from a chopper gun. Workers roll out the spray-up to compact the laminate. Wood, foam or other core material may then be added, and a secondary spray-up layer imbeds the core between the laminates. The part is then cured, cooled and removed from the reusable mold.

Pultrusion operation

Diagram of the pultrusion process.

Pultrusion is a manufacturing method used to make strong light weight composite materials, in this case fiberglass. Fibers (the glass material) are pulled from spools through a device that coats them with a resin. They are then typically heat-treated and cut to length. Pultrusions can be made in a variety of shapes or cross-sections such as a W or S cross-section. The word pultrusion describes the method of moving the fibers through the machinery. It is pulled through using either a hand over hand method or a continuous roller method. This is opposed to an extrusion, which would push the material through dies.

Chopped strand matChopped strand mat or CSM is a form of reinforcement used in fiberglass. It consists of glass fibers laid randomly across each other and held together by a binder.

It is typically processed using the hand lay-up technique, where sheets of material are placed in a mold and brushed with resin. Because the binder dissolves in resin, the material easily conforms to different shapes when wetted out. After the resin cures, the hardened product can be taken from the mold and finished.

Using chopped strand mat gives a fiberglass with isotropic in-plane material properties.

WarpingOne notable feature of fiberglass is that the resins used are subject to contraction during the curing process. For polyester this contraction is often of the order of 5-6%, and for epoxy it can be much lower, about 2%.

When formed as part of fiberglass, because the fibers don't contract, the differential can create changes in the shape of the part during cure. Distortions will usually appear hours, days or weeks after the resin has set.

While this can be minimised by symmetric use of the fibers in the design, nevertheless internal stresses are created, and if these become too great, then cracks will form.

Health problems

Air flow test for the extraction and filtration of styrene vapors in a production hall for GRP yachts

The National Toxicology Program ("NTP"), in June 2011, removed from its Report on Carcinogens all biosoluble glass wool used in home and building insulation and for non-insulation products.[8] Similarly, California's Office of Environmental Health Hazard Assessment ("OEHHA"), in November 2011, published a modification to its Proposition 65 listing to include only "Glass wool fibers (inhalable and biopersistent)."[9] The U.S. NTP and California's OEHHA action means that a cancer warning label for biosoluble fiber glass home and building insulation is no longer required under Federal or California law. All fiber glass wools commonly used for thermal and acoustical insulation were reclassified by the International Agency for Research on Cancer ("IARC") in October 2001 as Not Classifiable as to carcinogenicity to humans (Group 3).[10]The European Union and Germany classify synthetic vitreous fibers as possibly or probably carcinogenic, but fibers can be exempt from this classification if they pass specific tests. Evidence for these classifications is primarily from studies on experimental animals and mechanisms of carcinogenesis. The glass wool epidemiology studies have been reviewed by a panel of international experts convened by the International Agency for Research on Cancer ("IARC"). These experts concluded: "Epidemiologic studies published during the 15 years since the previous IARC monographs review of these fibres in 1988 provide no evidence of increased risks of lung cancer or mesothelioma (cancer of the lining of the body cavities) from occupational exposures during the manufacture of these materials, and inadequate evidence overall of any cancer risk."[10] Similar reviews of the epidemiology studies have been conducted by the Agency for Toxic Substances and Disease Registry ("ATSDR"),[11] the National Toxicology Program,[12] the National Academy of Sciences[13] and Harvard's Medical and Public Health Schools[14] which reached the same conclusion as IARC that there is no evidence of increased risk from occupational exposure to glass wool fibers.

Fiberglass will irritate the eyes, skin, and the respiratory system. Potential symptoms include irritation of eyes, skin, nose, throat, dyspnea (breathing difficulty); sore throat, hoarseness and cough.[15] Scientific evidence demonstrates that fiber glass is safe to manufacture, install and use when recommended work practices are followed to reduce temporary mechanical irritation.[16]Fiberglass is resistant to mold but growth can occur if fiberglass becomes wet and contaminated with organic material. Fiberglass insulation that has become wet should be inspected for evidence of residual moisture and contamination. Contaminated fiberglass insulation should be promptly removed.[17]While the resins are cured, styrene vapors are released. These are irritating to mucous membranes and respiratory tract. Therefore, the Hazardous Substances Ordinance in Germany dictate a maximum occupational exposure limit of 86mg/m. In certain concentrations may even occur a potentially explosive mixture. Further manufacture of GRP components (grinding, cutting, sawing) goes along with the emission of fine dusts and chips containing glass filaments as well as of tacky dust in substantial quantities. These affect people's health and functionality of machines and equipment. To ensure safety regulations are adhered to and efficiency can be sustained, the installation of effective extraction and filtration equipment is needed.[18]Fiber

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v t e

A bundle of optical fibersFiber (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.

Contents

1 Textile fiber 2 Natural fibers 3 Synthetic fibers

3.1 Metallic fibers 3.2 Carbon fiber 3.3 Silicon carbide fiber 3.4 Fiberglass 3.5 Mineral fibers 3.6 Cellulose fibers 3.7 Polymer fibers 3.8 Microfibers 4 See also 5 ReferencesTextile fiberA unit in which many complicated textile structures are built up is said to be textile fiber.

Natural fibersMain article: Natural fiberNatural 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.

Synthetic fibersMain article: Synthetic fiberSynthetic generally come from synthetic materials such as petrochemicals but some types of synthetic fibers are manufactured from natural cellulose, including rayon, modal, and Lyocell. Cellulose-based fibers are of two types, regenerated or pure cellulose such as from the cupro-ammonium process and modified cellulose such as the cellulose acetates.[2]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 general aspect ratio is between 200 to 500.[3]Metallic fibersMetallic 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 steel fibers.

Carbon fiberCarbon fibers are often based on oxydized and via pyrolysis carbonized polymers like PAN, but the end product is almost pure carbon.

Silicon carbide fiberSilicon 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.

FiberglassFiberglass, 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 fibersMineral fibers can be particularly strong because they are formed with a low number of surface defects, asbestos is a common one.[4]Cellulose fibersCellulose 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, seacell is made from seaweed, etc.

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:

polyamide nylon PET or PBT polyester phenol-formaldehyde (PF)

polyvinyl chloride fiber (PVC) vinyon polyolefins (PP and PE) olefin fiber 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.

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

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

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. 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.

MicrofibersMicrofibers 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.[2