Glass-reinforced plastic or GRP is a composite material Composite materials, often shortened to composites, are engineered materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct on a macroscopic level within the finished structure made of a plastic A plastic material is any of a wide range of synthetic or semi-synthetic organic amorphous solids[citation needed] used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce costs. Monomers of plastic are either natural or synthetic matrix reinforced by fine fibers Fiberglass, , is material made from extremely fine fibers of glass. It is used as a reinforcing agent for many polymer products; the resulting composite material, properly known as fiber-reinforced polymer (FRP) or glass-reinforced plastic (GRP), is called "fiberglass" in popular usage. Glassmakers throughout history have experimented made of glass Glass is an amorphous solid material. Glasses are typically brittle, and often optically transparent. Glass is commonly used for windows, bottles, and eyewear; examples of glassy materials include soda-lime glass, borosilicate glass, acrylic glass, sugar glass, Muscovy-glass, and aluminium oxynitride. The term glass developed in the late Roman. It is also known as GFK (for Glasfaserverstärkter 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 Epoxy or polyepoxide is a thermosetting polymer formed from reaction of an epoxide "resin" with polyamine "hardener". Epoxy has a wide range of applications, including fiber-reinforced plastic materials and general purpose adhesives, a thermosetting plastic Thermosetting plastics are polymer materials that irreversibly cure. The cure may be done through heat (generally above 200 degrees Celsius), through a chemical reaction (two-part epoxy, for example), or irradiation such as electron beam processing (most often polyester Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate . Polyesters include naturally-occurring chemicals, such as in the cutin of plant cuticles, as well as or vinylester Vinyl Ester, or Vinylester, is a resin produced by the esterification of an epoxy resin with an unsaturated monocarboxylic acid. The reaction product is then dissolved in a reactive solvent, such as styrene, to a 35 - 45 percent content by weight) or thermoplastic A thermoplastic, also known as thermosoftening plastic, is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently. Most thermoplastics are high-molecular-weight polymers whose chains associate through weak Van der Waals forces ; stronger dipole-dipole interactions and hydrogen bonding (nylon); or.
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Production
The manufacturing process for GRP fiber glass uses large furnaces to gradually melt the sand/chemical mix to liquid form, then extrude it through bundles of very small orifices (typically 17-25 micrometres in diameter for E-Glass, 9 micrometres for S-Glass). These filaments are then sized 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 1 km 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 wounding (pipe), gun roving (automated gun chops the glass into small 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.
Sizing
A sort of coating, or primer, 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 (which would buckle) to the thermoset plastic (which is quite good at handling shear loads), without this 'bonding', the fibers can 'slip' in the matrix and localised failure will ensue. {Citation needed|date=August 2009}. Usually also the basic material for making cloth.
Properties
An individual structural glass fiber is both stiff and strong in tension and compression—that 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. On the other hand, the glass fiber is unstiff and unstrong in shear—that 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 glass-reinforced plastic, 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 glass-reinforced plastic 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.
Applications
GRP is an immensely versatile material which combines lightweight with inherent strength to provide a weather resistant finish, with a variety of surface texture and an unlimited colour range available.
GRP was developed in the UK The United Kingdom of Great Britain and Northern Ireland[note 7] is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of the island of Ireland, and many small islands. Northern Ireland is the only part of the UK with a land during the Second World War Albania · Australia · Austria · Azerbaijan · Belarus · Belgium · Brazil · Bulgaria · Burma · Cambodia · Canada · Ceylon (Sri Lanka) · Channel Islands · China · Czechoslovakia · Denmark · Dutch East Indies · Egypt · Estonia · Finland · France · Germany · Gibraltar · Greece · Greenland · Hong Kong · Hungary · Iceland · as a replacement for the molded plywood used in aircraft radomes A radome is a structural, weatherproof enclosure that protects a microwave or radar antenna. The radome is constructed of material that minimally attenuates the electromagnetic signal transmitted or received by the antenna. In other words, the radome is transparent to radar or radio waves. Radomes protect the antenna surfaces from the environment ( (GRP being transparent to microwaves Microwaves are electromagnetic waves with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF (millimeter waves), and various sources use different boundaries. In all cases, microwave includes the entire SHF band (). Its first main civilian application was for building of boats A boat is a watercraft of modest size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is something small enough to be carried aboard another, where it gained acceptance in the 1950s. Its use has broadened to the automotive and sport equipment sectors as well as model aircraft, although its use there is now partly being taken over by carbon fiber Carbon fiber , alternatively graphite fiber, carbon graphite or CF, is a material consisting of extremely thin fibers about 0.005–0.010 mm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in microscopic crystals that are more or less aligned parallel to the long axis of the fiber. The crystal alignment makes which weighs less per given volume and is stronger both by volume and by weight. GRP uses also include hot tubs A hot tub is a large home-made or manufactured tub or small pool full of heated water and used for soaking, relaxation, massage, or hydrotherapy. In most cases, they have jets for massage purposes. Hot tubs are usually located outdoors, and are often sheltered for protection from the elements, as well as for privacy. Other variants in naming, 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.
GRP is also used in the telecommunications Telecommunication is the transmission of messages, over significant distances, for the purpose of communication. In earlier times, telecommunications involved the use of visual signals, such as smoke, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded drumbeats, lung-blown horns, or sent by loud whistles, for industry for shrouding Shroud usually refers to an item, such as a cloth, that covers or protects some other object. The term is most often used in reference to burial sheets, winding-cloths or winding-sheets, such as the famous Shroud of Turin or Tachrichim that Jews are dressed in for burial. Traditionally, burial shrouds are made of white cotton, wool or linen, the visual appearance of antennas An antenna is a transducer designed to transmit or receive electromagnetic waves. In other words, antennas convert electromagnetic waves into electrical currents and vice versa. They are used with waves in the radio part of the electromagnetic spectrum, that is, radio waves, and are a necessary part of all radio equipment. Antennas are used in, due to its RF Radio frequency is a rate of oscillation in the range of about 30 kHz to 300 GHz, which corresponds to the frequency of electrical signals normally used to produce and detect radio waves. RF usually refers to electrical rather than mechanical oscillations, although mechanical RF systems do exist (see mechanical filter and RF MEMS) permeability and low signal attenuation In physics, attenuation is the gradual loss in intensity of any kind of flux through a medium. For instance, sunlight is attenuated by dark glasses, and X-rays are attenuated by lead 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 Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten. Carbon and other elements act as a hardening agent, preventing 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.
Storage tanks
Storage tanks A storage tank is a container, usually for holding liquids, sometimes for compressed gases . The term can be used for reservoirs (artificial lakes and ponds), and for manufactured containers. The usage of the word tank for reservoirs is common or universal in Indian English, American English and moderately common in British English. In other can be made of GRP with capacities up to about 300 tonnes. The smaller tanks can be made with chopped strand mat cast over a thermoplastic A thermoplastic, also known as thermosoftening plastic, is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently. Most thermoplastics are high-molecular-weight polymers whose chains associate through weak Van der Waals forces ; stronger dipole-dipole interactions and hydrogen bonding (nylon); or 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 Polypropylene , also known as polypropene, is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including packaging, textiles (e.g. ropes, thermal underwear and carpets), stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components,) is resistant to a wide range of strong chemicals. GRP tanks are also used for septic tanks A septic tank, the key component of the septic system, is a small scale sewage treatment system common in areas with no connection to main sewage pipes provided by local governments or private corporations. Septic systems are a type of On-Site Sewage Facility (OSSF). In North America approximately 25% of the population relies on septic tanks; this.
House building
Glass 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 GRP 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 GRP 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.
Piping
GRP 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 methods
Fiberglass hand lay-up operation
Resin is mixed with a catalyst or hardener if working with epoxy Epoxy or polyepoxide is a thermosetting polymer formed from reaction of an epoxide "resin" with polyamine "hardener". Epoxy has a wide range of applications, including fiber-reinforced plastic materials and general purpose adhesives, otherwise it will not cure (harden) for days/ weeks. Next, the mold is wetted out with the mixture. The sheets of fiberglass are placed over the mold and rolled down into the mold using steel rollers. The material must be securely attached to the mold, air must not be trapped in between the fiberglass and the mold. Additional resin is applied and possibly additional sheets of fiberglass. Rollers are used to make sure the resin is between all the layers, the glass is wetted throughout the entire thickness of the laminate, and any air pockets are removed. The work must be done quickly enough to complete the job before the resin starts to cure. Various curing times can be achieved by altering the amount of catalyst employed.
Fiberglass spray lay-up operation
The 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
Pultrusion is a manufacturing method used to make strong light weight composite materials Composite materials, often shortened to composites, are engineered materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct on a macroscopic level within the finished structure, 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.[1] 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 Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed or drawn through a die of the desired cross-section. The two main advantages of this process over other manufacturing processes are its ability to create very complex cross-sections and work materials that are brittle, because the material only which would push the material through dies.
Chopped strand mat
Chopped strand mat or CSM is a form of reinforcement used in glass-reinforced plastic. It consists of glass-fibers Fiberglass, , is material made from extremely fine fibers of glass. It is used as a reinforcing agent for many polymer products; the resulting composite material, properly known as fiber-reinforced polymer (FRP) or glass-reinforced plastic (GRP), is called "fiberglass" in popular usage. Glassmakers throughout history have experimented 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 glass-reinforced plastic with isotropic Isotropy is uniformity in all directions. Precise definitions depend on the subject area. The word is made up from Greek iso and tropos (direction). Exceptions, or inequalities, are frequently indicated by the prefix an, hence anisotropy. Anisotropy is also used to describe situations where properties vary systematically, dependent on direction in-plane material properties.
Examples of GRP use
Kayaks A kayak is a small human-powered boat that traditionally has a covered deck, and one or more cockpits, each seating one paddler who strokes a double-bladed paddle. The cockpit is covered by a spraydeck that keeps the inside of the boat (and the paddler's lower body) dry. The spraydeck or similar waterproof covering attaches securely to the edges made of GRP.- Gliders A glider or sailplane is a type of glider aircraft used in the sport of gliding. Some gliders, known as motor gliders are used for gliding and soaring as well, but have engines which can, in some cases, be used for take-off or for extending a flight. Foot-launched aircraft are described in separate articles, though their differences to sailplanes, kit cars A kit car is an automobile that is available in kit form, which means that the client buys a set of parts and then assembles the car themselves. Usually many major mechanical parts such as the engine and transmission are taken from one or more donor vehicles. Kits vary in completeness from as little as a book of plans to a complete set of all the, sports cars, microcars, karts, bodyshells, boats, kayaks, flat roofs, lorries, wind turbine A wind turbine is a rotary device that extracts energy from the wind. If the mechanical energy is used directly by machinery, such as for pumping water, cutting lumber or grinding stones, the machine is called a windmill. If the mechanical energy is instead converted to electricity, the machine is called a wind generator, wind turbine, wind blades.
- Pods, domes and architectural features where a light weight is necessary.
- Bodies for automobiles, such as the Chevrolet Corvette The Chevrolet Corvette is an American sports car by the Chevrolet division of General Motors. The first model was designed by Harley Earl and introduced in 1953. Myron Scott is credited for naming the car after the corvette, a small, maneuverable warship. It has been produced in six generations in coupe, convertible, t-top coupe, and targa coupe and Studebaker Avanti, and DeLorean DMC-12 under body.
- A320 The Airbus A320 family of short- to medium-range commercial passenger airliners are manufactured by Airbus and are the only narrowbody in their product line. Family members include the A318, A319, A320, and A321, as well as the ACJ business jet radome A radome is a structural, weatherproof enclosure that protects a microwave or radar antenna. The radome is constructed of material that minimally attenuates the electromagnetic signal transmitted or received by the antenna. In other words, the radome is transparent to radar or radio waves. Radomes protect the antenna surfaces from the environment (.
- FRP tanks and vessels FRP is a modern composite material of construction for chemical plant equipment like tanks and vessels. Chemical equipment that range in size from less than a meter to 20 meters are fabricated using FRP as material of construction: FRP is used extensively to manufacture chemical equipments and tanks and vessels. BS4994 is a British standard related to this application.
- UHF-broadcasting antennas are often mounted inside a glass-reinforced plastic cylinder on the pinnacle of a broadcasting tower
- Thinkpads from Lenovo/IBM
References
Categories: Composite materials | Glass applications
Wed, 07 Jul 2010 13:07:28 GMT+00:00
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