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rubber1

  (rŭb'ər) pronunciation
n.
  1. A yellowish, amorphous, elastic material obtained from the milky sap or latex of various tropical plants, especially the rubber tree, and vulcanized, pigmented, finished, and modified into products such as electric insulation, elastic bands and belts, tires, and containers. Also called caoutchouc, India rubber.
  2. Any of numerous synthetic elastic materials of varying chemical composition with properties similar to those of natural rubber.
  3. A low overshoe made of rubber.
  4. Baseball. The rectangular piece of hard rubber that the pitcher must remain in contact with when making a pitch.
  5. Something made of rubber, as:
    1. An eraser.
    2. A tire.
    3. A set of tires on a vehicle.
  6. Slang. A condom.
  7. One that rubs, especially one that gives a massage.

[From RUB.]


rub·ber2 (rŭb'ər) pronunciation
n.
  1. A series of games of which two out of three or three out of five must be won to terminate the play.
  2. An odd game played to break a tie.

[Origin unknown.]


 
 
Sci-Tech Encyclopedia: Rubber

Originally, a natural or tree rubber, which is a hydrocarbon polymer of isoprene units. With the development of synthetic rubbers having some rubbery characteristics but differing in chemical structure as well as properties, a more general designation was needed to cover both natural and synthetic rubbers. The term elastomer, a contraction of the words elastic and polymer, was introduced, and defined as a substance that can be stretched at room temperature to at least twice its original length and, after having been stretched and the stress removed, returns with force to approximately its original length in a short time.

Three requirements must be met for rubbery properties to be present in both natural and synthetic rubbers: long thread like molecules, flexibility in the molecular chain to allow flexing and coiling, and some mechanical or chemical bonds between molecules.

Natural rubber and most synthetic rubbers are also commercially available in the form of latex, a colloidal suspension of polymers in an aqueous medium. Natural rubber comes from trees in this form; many synthetic rubbers are polymerized in this form; some other solid polymers can be dispersed in water. See also Polymer.

Latexes are the basis for a technology and production methods completely different from the conventional methods used with solid rubbers.

In the crude state, natural and synthetic rubbers possess certain physical properties which must be modified to obtain useful end products. The raw or unmodified forms are weak and adhesive. They lose their elasticity with use, change markedly in physical properties with temperature, and are degraded by air and sunlight. Consequently, it is necessary to transform the crude rubbers by compounding and vulcanization procedures into products which can better fulfill a specific function.

Although natural rubber may be obtained from hundreds of different plant species, the most important source is the rubber tree (Hevea brasiliensis). Natural rubber is cis-1,4-polyisoprene, containing approximately 5000 isoprene units in the average polymer chain.

Styrene-butadiene rubber (SBR) is the most important synthetic rubber and the most widely used rubber in the entire world. Formerly designated GR-S, SBRs are obtained by the emulsion polymerization of butadiene and styrene in varying ratios. However, in the most commonly used type, the ratio of butadiene to styrene is approximately 78:22. Unlike natural rubber, SBR does not crystallize on stretching and thus has low tensile strength unless reinforced. The major use for SBR is in tires and tire products. Other uses include belting, hose, wire and cable coatings, flooring, shoe products, sponge, insulation, and molded goods.

Butyl rubber is essentially a polyisobutylene except for the presence of diolefin, usually isoprene, to provide the unsaturation necessary for vulcanization. Butyl rubbers have excellent resistance to oxygen, ozone, and weathering. In addition, these rubbers exhibit good electrical properties and high impermeability to gases. The high impermeability to gases results in use of butyl as an inner liner in tubeless tires. Other widespread uses are for wire and cable products, injection-molded and extruded products, hose, gaskets, and sealants, and where good damping characteristics are needed.

Ethylene-propylene polymers are produced by the copolymerization of ethylene and propylene. These copolymers exhibit outstanding resistance to heat, oxygen, ozone, and other aging and degrading agents. Abrasion resistance in tire treads is excellent. The mechanical properties of their vulcanizates are generally approximately equivalent to those of SBR.

One of the first synthetic rubbers used commercially in the rubber industry is neoprene, a polymer of chloroprene, 2-chlorobutadiene-1,3. The neoprenes have exceptional resistance to weather, sun, ozone, and abrasion. They are good in resilience, gas impermeability, and resistance to heat, oil, and flame. They are fairly good in low temperature and electrical properties. This versatility makes them useful in many applications requiring oil, weather, abrasion, or electrical resistance or combinations of these properties, such as wire and cable, hose, belts, molded and extruded goods, soles and heels, and adhesives.

Nitrile-type rubbers are copolymers of acrylonitrile and a diene, usually butadiene. The nitrile rubbers can be blended with natural rubber, polysulfide rubbers, and various resins to provide characteristics such as increased tensile strength, better solvent resistance, and improved weathering resistance.

Fluoroelastomers are basically copolymers of vinylidene fluoride and hexafluoropropylene. Because of their fluorine content, they are the most chemically resistant of the elastomers and also have good properties under extremes of temperature conditions. They are useful in the aircraft, automotive, and industrial areas.

Polyurethane elastomers are of interest because of their versatility and variety of properties and uses. They can be used as liquids or solids in a number of manufacturing methods. The largest use has been for making foam for upholstery and bedding. See also Polyurethane resins.

Polysulfide rubbers have a large amount of surlfur in the main polymer chain and are therefore very chemically resistant, particularly to oils and solvents. They are used in such applications as putties, caulks, and hose for paint spray, gasoline, and fuel. Polyacrylate rubbers are useful because of their resistance to oils at high temperatures, including sulfur-bearing extreme-pressure lubricants. See also Polysulfide resins.

Proper choice of catalyst and order of procedure in polymerization have led to development of thermoplastic elastomers. The leading commercial types are styrene block copolymers having a structure which consists of polystyrene segments or blocks connected by rubbery polymers such as polybutadiene, polyisoprene, or ethylene-butylene polymer. Thermoplastic elastomers are very useful in providing a fast and economical method of producing a variety of products. One of the disadvantages for many applications is the low softening point of the thermoplastic elastomers.

 
Britannica Concise Encyclopedia: rubber

Flexible material that can recover its shape after considerable deformation.The best-known rubber is natural rubber, made from the milky latex of the rubber tree (Hevea brasiliensis). Natural rubber is still important industrially, but it now competes with synthetic alternatives (e.g., neoprene, silicone) derived from petroleum, natural gas, and other source materials. Rubber's usefulness is based on the unique elasticity of its constituent polymer molecules (built of thousands of isoprene monomers; see isoprenoid), which are capable of returning to their original coiled shape after being stretched to great extents; it is made more durable by vulcanization with sulfur or another agent that establishes chemical cross-links between the polymers. Fillers and other additives allow tailoring of properties to the desired use (e.g., by foaming, shaping, and curing). More than half of all rubber goes into making tires; the rest is used principally in belts, hoses, gaskets, shoes, clothing, furniture, and toys.

For more information on rubber, visit Britannica.com.

 
Architecture: rubber


1. A highly resilient material, capable of recovering from large deformations quickly; manufactured from the juice of rubber trees as well as of other trees and plants.
2. Any of various synthetically produced materials having similar properties; an elastomer.
3. A cutter.

 
Archaeology Dictionary: rubber

[Ar]

A small bun-shaped block of coarse stone used as the upper stone in a saddle quern or for grinding and crushing seeds or plant material in a bone basin or mortar.
 
US History Encyclopedia: Rubber

Although rubber-yielding plants are native to Africa and Asia as well as to the Americas, the first mention of rubber in the West was made by Pietro Martire d'Anghiera, the Italian representative to the court of Spain (De Rebus Oceanicis et Novo Orbe, 1516). In the early seventeenth century, Juan de Torquemada (Monarquía Indiana, 1615) described how the Mexican Indians used a milk-like fluid drawn from a tree for religious rites and sport, and for making crude footwear, waterproof bottles, and garments. Although a little rubber was used in Europe in the eighteenth century to make erasers—it derived its name "rubber" for its property of rubbing out (erasing) pencil marks—along with elastic thread, surgical tubes, and experimental balloons, the rubber manufacturing industry was not established until the nineteenth century.

The first record of rubber in the United States is a patent for gum elastic varnish for footwear issued to Jacob F. Hummel in 1813. This was followed by a patent for a grinding and mixing machine granted to John J. Howe in 1820. Prompting these first steps was the profitable trade in crude rubber shoes imported into Boston and New York City from Brazil. By 1833, America's pioneering rubber factory was established at Roxbury, Massachusetts. Other rubber shoe and clothing factories soon appeared elsewhere in Massachusetts, as well as in New Jersey, Rhode Island, Connecticut, New York, and Pennsylvania. By 1840, the infant industry had experienced a speculative boom (about $2 million in stock was issued) and a disastrous collapse. The primary cause for the loss of confidence was that rubber products had not proven reliable—they softened in the heat and stiffened in the cold—but the downturn in general business conditions that began in the fall of 1837 only added to the industry's distress. So great were the industry's troubles that in 1843 the Roxbury Rubber Company sold the "monster" spreading machine (built by Edwin Marcus Chaffee in 1837) for $525; it had been purchased for $30,000.

Although experiments to cure rubber have been attributed to the eighteenth-century Swedish physician and pharmacist Petter-Jonas Bergius, it remained for Charles Goodyear to solve the basic technical problem confronting early rubber manufacturers. He did so in 1839, at Woburn, Massachusetts, when he developed the "vulcanization process," which gives rubber durability and consistent qualities across a broad range of temperatures by treating it with sulfur and white lead at a high temperature. His samples of "cured" rubber, with which he tried to raise funds in England, prompted the English inventor Thomas Hancock to make his own "discovery" of vulcanization. The "elastic metal" provided by these two inventors would soon prove indispensable to the Western world.

Nowhere was this more marked than in the development of the Automobile Industry. Yet long before the automobile appeared at the end of the nineteenth century, America's consumption of raw rubber had grown twenty fold—from 1,120 short tons in 1850 to 23,000 tons in 1900 (two-fifths of the world total of 59,000 short tons). Wherever elastic, shock-absorbing, water-resistant, insulating, and air-and steam-tight properties were required, vulcanized rubber was used. Most of the raw rubber came from Brazil, with Africa the second-most important source. The problem was not to find rubber but to find the labor to collect it in the almost inaccessible forests and ship it to the factories of the Northern Hemisphere. Until the systematic development of plantation rubber in Southeast Asia in the twentieth century made collection and transportation a comparatively easy task, the growing demand for crude rubber could only be met at increased cost. In 1830, Para rubber was 20 cents a pound; in 1900 the annual average wholesale price had risen to about a dollar.

Between 1849 and 1900, the industry's output of manufactured goods—chiefly footwear, mechanicals (for use with machinery), proofed and elastic goods, surgical goods, bicycle tires, and toys—increased in value from $3 million to $53 million. In the same years, the industry's workforce grew from 2,500 to 22,000. Because of the economies of scale and the absence of product differentiation, the market for rubber products was fiercely competitive—hence the tendency for the early rubber manufacturers to band together. Before the Civil War, marketing arrangements were already in existence to control the sale of footwear and other products. By the eve of World War I, production had come to be dominated by the "Big Four": Goodyear Tire and Rubber Company, United States Rubber Company, B. F. Goodrich Company, and Firestone Tire and Rubber Company. Partly to be close to the carriage-making industry—at the time the rubber industry's major consumer—the center of rubber manufacture had shifted from the towns of New England to Akron, Ohio. The industry's first branch factories were established in Western Europe in the 1850s.

The most dramatic phase of the industry's growth followed the introduction of the internal combustion engine, cheap petroleum, and the widespread use of the pneumatic tire in the early 1900s. Between 1900 and 1920, consumption of raw rubber increased tenfold—to 231,000 short tons. Even the world depression of the early 1930s only temporarily halted the industry's rapid expansion. By 1940, the United States was consuming 726,000 tons of a world total of 1,243,000 tons of crude rubber. Between 1900 (when the first four tons of Southeast Asia plantation rubber had reached the market) and 1910, the annual average wholesale price per pound of crude rubber doubled from $1 to $2. By 1915, more than twice as much rubber was coming from the plantations of Southeast Asia than from America and Africa combined, and prices had fallen to a quarter of their 1910 level; on 2 June 1932, the price was just three cents a pound.

Partly because of the great fluctuations in the price of crude rubber, and partly because the plantation industry of the Far East was largely in British hands, the industry began a search for rubber substitutes in the 1920s. In the next decade, manufacturers produced a few hundred tons a year of a special type of synthetic rubber. As Japan seized the rubber lands of Southeast Asia during World War II, U.S. production of synthetic rubber increased a hundredfold—from 9,000 short tons in 1941 to 919,000 tons in 1945, at which point synthetic rubber met four-fifths of America's needs. By 1973, of a world output of 6.3 million metric tons, the United States produced about 40 percent, almost three times more than the next greatest producer, Japan. That year, the United States had consumed only 696,000 metric tons of a world output of approximately 3.5 million tons of natural rubber.

Chemists succeeded in not only synthesizing rubber by making a wide range of elastomers and plastomers available, they changed the character of the industry until it was no longer possible to distinguish between rubber and rubber substitutes. The price of the synthetic compared favorably with that of the natural product, and for some uses synthetic rubber was preferable.

The rise of other industrialized nations in the twentieth century reduced America's domination of the industry; even so, its output in 1970 (including plastics) was worth about $15 billion and the industry employed more than half a million workers. In 1987, the American rubber industry shipped $24.9 billion in goods, of which automobile tires accounted for $10.5 billion of that amount. According to the Environmental Protection Agency, more than 230,000 people were employed in the rubber industry in the United States in 1987. Although rubber was used in thousands of ways, automobile tires—with which the major technical developments in manufacture have been associated—continued to account for more than one-half of the industry's consumption of raw materials. The overwhelming size of the major rubber corporations (a fifth giant was added to the Big Four in 1915 when the General Tire and Rubber Corporation was formed at Akron) did not lessen the industry's competitive nature. After World War II, the tendency toward global expansion increased, and, in the late twentieth century, the major rubber manufacturers were worldwide in scope and operation.

Bibliography

Allen, P. W. Natural Rubber and the Synthetics. New York: Wiley, 1972.

EPA Office of Compliance Sector. Profile of the Rubber and Plastic Industry. Washington, D.C.: U.S. Environmental Protection Agency, 1995.

Howard, Frank A. Buna Rubber: The Birth of an Industry. New York: Van Nostrand, 1947.

Phillips, Charles F. Competition in the Synthetic Rubber Industry. Chapel Hill: University of North Carolina Press, 1963.

Schidrowitz, Philip, and T. R. Dawson, eds. History of the Rubber Industry. Cambridge, U.K.: Heffer, 1952.

Woodruff, W. "Growth of the Rubber Industry of Great Britain and the United States." Journal of Economic History 15, no. 4 (1955): 376–391.

 
Columbia Encyclopedia: rubber,
any solid substance that upon vulcanization becomes elastic; the term includes natural rubber (caoutchouc) and synthetic rubber. The term elastomer is sometimes used to designate synthetic rubber only and is sometimes extended to include caoutchouc as well.

Chemistry and Properties

All rubberlike materials are polymers, which are high molecular weight compounds consisting of long chains of one or more types of molecules, such as monomers. Vulcanization (or curing) produces chemical links between the loosely coiled polymeric chains; elasticity occurs because the chains can be stretched and the crosslinks cause them to spring back when the stress is released. Natural rubber is a polyterpene, i.e., it consists of isoprene molecules linked into loosely twisted chains. The monomer units along the backbone of the carbon chains are in a cis arrangement (see isomer) and it is this spatial configuration that gives rubber its highly elastic character. In gutta-percha, which is another natural polyterpene, the isoprene molecules are bonded in a trans configuration leading to a crystalline solid at room temperature. Unvulcanized rubber is soluble in a number of hydrocarbons, including benzene, toluene, gasoline, and lubricating oils.

Rubber is water repellent and resistant to alkalies and weak acids. Rubber's elasticity, toughness, impermeability, adhesiveness, and electrical resistance make it useful as an adhesive, a coating composition, a fiber, a molding compound, and an electrical insulator. In general, synthetic rubber has the following advantages over natural rubber: better aging and weathering, more resistance to oil, solvents, oxygen, ozone, and certain chemicals, and resilience over a wider temperature range. The advantages of natural rubber are less buildup of heat from flexing and greater resistance to tearing when hot.

Natural Rubber

Natural rubber is obtained from the milky secretion (latex) of various plants, but the only important commercial source of natural rubber (sometimes called Pará rubber) is the tree Hevea brasiliensis. The only other plant under cultivation as a commercial rubber source is guayule (Parthenium argentatum), a shrub native to the arid regions of Mexico and the SW United States. To soften the rubber so that compounding ingredients can be added, the long polymer chains must be partially broken by mastication, mechanical shearing forces applied by passing the rubber between rollers or rotating blades. Thus, for most purposes, the rubber is ground, dissolved in a suitable solvent, and compounded with other ingredients, e.g., fillers and pigments such as carbon black for strength and whiting for stiffening; antioxidants; plasticizers, usually in the form of oils, waxes, or tars; accelerators; and vulcanizing agents. The compounded rubber is sheeted, extruded in special shapes, applied as coating or molded, then vulcanized. Most Pará rubber is exported as crude rubber and prepared for market by rolling slabs of latex coagulated with acid into thin sheets of crepe rubber or into heavier, firmly pressed sheets that are usually ribbed and smoked.

An increasing quantity of latex, treated with alkali to prevent coagulation, is shipped for processing in manufacturing centers. Much of it is used to make foam rubber by beating air into it before pouring it into a vulcanizing mold. Other products are made by dipping a mold into latex (e.g., rubber gloves) or by casting latex. Sponge rubber is prepared by adding to ordinary rubber a powder that forms a gas during vulcanization. Most of the rubber imported into the United States is used in tires and tire products; other items that account for large quantities are belting, hose, tubing, insulators, valves, gaskets, and footwear. Uncoagulated latex, compounded with colloidal emulsions and dispersions, is extruded as thread, coated on other materials, or beaten to a foam and used as sponge rubber. Used and waste rubber may be reclaimed by grinding followed by devulcanization with steam and chemicals, refining, and remanufacture.

Synthetic rubber

The more than one dozen major classes of synthetic rubber are made of raw material derived from petroleum, coal, oil, natural gas, and acetylene. Many of them are copolymers, i.e., polymers consisting of more than one monomer. By changing the composition it is possible to achieve specific properties desired for special applications. The earliest synthetic rubbers were the styrene-butadiene copolymers, Buna S and SBR, whose properties are closest to those of natural rubber. SBR is the most commonly used elastomer because of its low cost and good properties; it is used mainly for tires. Other general purpose elastomers are cis-polybutadiene and cis-polyisoprene, whose properties are also close to that of natural rubber.

Among the specialty elastomers are copolymers of acrylonitrile and butadiene that were originally called Buna N and are now known as nitrile elastomers or NBR rubbers. They have excellent oil resistance and are widely used for flexible couplings, hoses, and washing machine parts. Butyl rubbers are copolymers of isobutylene and 1.3% isoprene; they are valuable because of their good resistance to abrasion, low gas permeability, and high dielectric strength. Neoprene (polychloroprene) is particularly useful at elevated temperatures and is used for heavy-duty applications. Ethylene-propylene rubbers (RPDM) with their high resistance to weathering and sunlight are used for automobile parts, hose, electrical insulation, and footwear. Urethane elastomers are called spandex and they consist of urethane blocks and polyether or polyester blocks; the urethane blocks provide strength and heat resistance, the polyester and polyether blocks provide elasticity; they are the most versatile elastomer family because of their hardness, strength, oil resistance, and aging characteristics. They have replaced rubber in elasticized materials. Other uses range from airplane wheels to seat cushions. Other synthetics are highly oil-resistant, but their high cost limits their use. Silicone rubbers are organic derivatives of inorganic polymers, e.g., the polymer of dimethysilanediol. Very stable and flexible over a wide temperature range, they are used in wire and cable insulation.

History

Pre-Columbian peoples of South and Central America used rubber for balls, containers, and shoes and for waterproofing fabrics. Mentioned by Spanish and Portuguese writers in the 16th cent., rubber did not attract the interest of Europeans until reports about it were made (1736–51) to the French Academy of Sciences by Charles de la Condamine and François Fresneau. Pioneer research in finding rubber solvents and in waterproofing fabrics was done before 1800, but rubber was used only for elastic bands and erasers, and these were made by cutting up pieces imported from Brazil. Joseph Priestley is credited with the discovery c.1770 of its use as an eraser, thus the name rubber.

The first rubber factory in the world was established near Paris in 1803, the first in England by Thomas Hancock in 1820. Hancock devised the forerunner of the masticator (the rollers through which the rubber is passed to partially break the polymer chains), and in 1835 Edwin Chaffee, an American, patented a mixing mill and a calender (a press for rolling the rubber into sheets).

In 1823, Charles Macintosh found a practical process for waterproofing fabrics, and in 1839 Charles Goodyear discovered vulcanization, which revolutionized the rubber industry. In the latter half of the 19th cent. the demand for rubber insulation by the electrical industry and the invention of the pneumatic tire extended the demand for rubber. In the 19th cent. wild rubber was harvested in South and Central America and in Africa; most of it came from the Pará rubber tree of the Amazon basin.

Despite Brazil's legal restrictions, seeds of the tree were smuggled to England in 1876. The resultant seedlings were sent to Ceylon (Sri Lanka) and later to many tropical regions, especially the Malay area and Java and Sumatra, beginning the enormous East Asian rubber industry. Here the plantations were so carefully cultivated and managed that the relative importance of Amazon rubber diminished. American rubber companies, as a step toward diminishing foreign control of the supply, enlarged their plantation holdings in Liberia and in South and Central America.

During World War I, Germany made a synthetic rubber, but it was too expensive for peacetime use. In 1927 a less costly variety was invented, and in 1931 neoprene was made, both in the United States. German scientists developed Buna rubber just prior to World War II. When importation of natural rubber from the East Indies was cut off during World War II, the United States began large-scale manufacture of synthetic rubber, concentrating on Buna S. Today synthetic rubber accounts for about 60% of the world's rubber production.

Bibliography

See P. W. Allen, Natural Rubber and the Synthetics (1972); M. Morton, Rubber Technology (3d ed. 1987).

 
Word Tutor: rubber
pronunciation

IN BRIEF: n. - An elastic resilient cohesive solid made from the juice of certain tropical trees.

pronunciation Children love rubber balls because they bounce high.

 
Wikipedia: rubber
This article is about the polymeric material. For other uses, see Rubber (disambiguation).
Latex being collected from a tapped rubber tree
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Latex being collected from a tapped rubber tree

Natural rubber is an elastic hydrocarbon polymer that naturally occurs as a milky colloidal suspension, or latex, in the sap of some plants. It can also be synthesized. The entropy model of rubber was developed in 1934 by Werner Kuhn.

Explanation

The major commercial source of natural rubber latex is the Para rubber tree, Hevea brasiliensis (Euphorbiaceae). This is largely because it responds to wounding by producing more latex. Henry Wickham gathered thousands of seeds from Brazil in 1876 and they were germinated in Kew Gardens, England. The seedlings were sent to Colombo, Indonesia, Singapore and British Malaya. Malaya was later to become the biggest producer of rubber. Liberia and Nigeria are examples of African rubber-producing countries.

Other plants containing latex include figs (Ficus elastica), euphorbias, and the common dandelion. Although these have not been major sources of rubber, Germany attempted to use such sources during World War II when it was cut off from rubber supplies. These attempts were later supplanted by the development of synthetic rubber.

Synthetic rubbers are made by the polymerization of a single monomer or a mixture of monomers to produce polymers. These form part of a broad range of products extensively studied by polymer science and rubber technology. Examples are SBR, or styrene-butadiene rubber, BR or butadiene rubber CR or chloroprene rubber and EPDM (ethylene-propylene-diene rubber)

Collection

A woman in Sri Lanka in the process of harvesting rubber.
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A woman in Sri Lanka in the process of harvesting rubber.

In places like Kerala, where coconuts are in abundance, the shell of half a coconut is used as the collection container for the latex. The shells are attached to the tree via a short sharp stick and the latex drips down into it overnight. This usually produces latex up to a level of half to three quarters of the shell. The latex from multiple trees is then poured into flat pans, and this is mixed with formic acid, which serves as a coagulant resulting in rubber crump. After a few hours, the very wet sheets of rubber are wrung out by putting them through a press before they are sent onto factories where vulcanization and further processing is done to it.

Chemical makeup

Aside from a few natural product impurities, natural rubber is essentially a polymer of isoprene units, a hydrocarbon diene monomer. Synthetic rubber can be made as a polymer of isoprene or various other monomers. Rubber is believed to have been named by Joseph Priestley, who discovered in 1770 that dried latex rubbed out pencil marks. The material properties of natural rubber make it an elastomer and a thermoplastic. However it should be noted that as the rubber is vulcanized it will turn into a thermoset. Most rubber in everyday use is vulcanized to a point where it shares properties of both i.e. if it is heated and cooled it is degraded but not destroyed.

History

In its native Central America and South America, rubber has been collected for a long time. The Mesoamerican civilizations used rubber mostly from Castilla elastica. The Ancient Mesoamericans had a ball game using rubber balls (see: Mesoamerican ballgame), and a few Pre-Columbian rubber balls have been found (always in sites that were flooded under fresh water), the earliest dating to about 1600 BC. According to Bernal Díaz del Castillo, the Spanish Conquistadores were so astounded by the vigorous bouncing of the rubber balls of the Aztecs that they wondered if the balls were enchanted by evil spirits. The Maya also made a type of temporary rubber shoe by dipping their feet into a latex mixture. Rubber was used in various other contexts, such as strips to hold stone and metal tools to wooden handles, and padding for the tool handles. While the ancient Mesoamericans did not have vulcanization, they developed organic methods of processing the rubber with similar results, mixing the raw latex with various saps and juices of other vines, particularly Ipomoea alba, a species of Morning glory. In Brazil the natives understood the use of rubber to make water-resistant cloth. A story says that the first European to return to Portugal from Brazil with samples of such water-repellent rubberized cloth so shocked people that he was brought to court on the charge of witchcraft.

When samples of rubber first arrived in England, it was observed by Joseph Priestley, in 1770, that a piece of the material was extremely good for rubbing out pencil marks on paper, hence the name eraser.

The para rubber tree initially grew in South America, where it was the main source of what limited amount of latex rubber was consumed during much of the 19th century. About 100 years ago, the Congo Free State in Africa was a significant source of natural rubber latex, mostly gathered by forced labor. The Congo Free State was forged and ruled as a personal colony by the Belgian King Leopold II. After repeated efforts (see Henry Wickham) rubber was successfully cultivated in Southeast Asia, where it is now widely grown.

In India commercial cultivation of natural rubber was introduced by the British Planters, although the experimental efforts to grow rubber on a commercial scale in India were initiated as early as 1873 at the Botanical Gardens, Kolkata. The first commercial Hevea plantations in India were established at Thattekadu in Kerala in 1902.

The Rubber Board is a statutory body constituted by the Government of India, under the Rubber Act 1947, for the overall development of the rubber industry in the country.The head office of the rubber board is situated in Kottayam, Kerala, where the main production of natural rubber.

Properties

Rubber latex.
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Rubber latex.

Rubber exhibits unique physical and chemical properties.

Rubber's stress-strain behavior exhibits the Mullins effect, the Payne effect and is often modeled as hyperelastic.

Rubber strain crystallizes.

Why does rubber have elasticity?

In most elastic materials, such as metals used in springs, the elastic behavior is caused by bond distortions. When force is applied, bond lengths deviate from the (minimum energy) equilibrium and strain energy is stored electrostatically. Rubber is often assumed to behave in the same way, but it turns out this is a poor description. Rubber is a curious material because, unlike metals, strain energy is stored thermally, as well as electrostatically.

In its relaxed state rubber consists of long, coiled-up polymer chains that are interlinked at a few points. Between a pair of links each monomer can rotate freely about its neighbour. This gives each section of chain leeway to assume a large number of geometries, like a very loose rope attached to a pair of fixed points. At room temperature rubber stores enough kinetic energy so that each section of chain oscillates chaotically, like the above piece of rope being shaken violently.

When rubber is stretched the "loose pieces of rope" are taut and thus no longer able to oscillate. Their kinetic energy is given off as excess heat. Therefore, the entropy decreases when going from the relaxed to the stretched state, and it increases during relaxation. This change in entropy can also be explained by the fact that a tight section of chain can fold in fewer ways (W) than a loose section of chain, at a given temperature (nb. entropy is defined as S=k*ln(W)). Relaxation of a stretched rubber band is thus driven by an increase in entropy, and the force experienced is not electrostatic, rather it is a result of the thermal energy of the material being converted to kinetic energy. Rubber relaxation is endothermic. The material undergoes adiabatic cooling during contraction. This property of rubber can easily be verified by holding a stretched rubber band to your lips and relaxing it.

Stretching of a rubber band is in some ways equivalent to the compression of an ideal gas, and relaxation in equivalent to its expansion. Note that a compressed gas also exhibits "elastic" properties, for instance inside an inflated car tire. The fact that stretching is equivalent to compression may seem somewhat counter-intuitive, but it makes sense if rubber is viewed as a one-dimensional gas. Stretching reduces the "space" available to each section of chain.

Vulcanization of rubber creates more disulphide bonds between chains so it makes each free section of chain shorter. The result is that the chains tighten more quickly for a given length of strain. This increases the elastic force constant and makes rubber harder and less extendable.

When cooled below the glass transition temperature, the quasi-fluid chain segments "freeze" into fixed geometries and the rubber abruptly loses its elastic properties, though the process is reversible. This is a property it shares with most elastomers. At very cold temperatures rubber is actually rather brittle; it will break into shards when struck or stretched. This critical temperature is the reason that winter tires use a softer version of rubber than normal tires. The failing rubber o-ring seals that contributed to the cause of the Challenger disaster were thought to have cooled below their critical temperature. The disaster happened on an unusually cold day.

Current sources of rubber

Close to 21 million tons of rubber were produced in 2005 of which around 42% was natural. Today Asia is the main source of natural rubber, accounting for around 94% of output in 2005. The three largest producing countries (Indonesia, Malaysia and Thailand) together account for around 72% of all natural rubber production.

Hypoallergenic rubber can be made from Guayule.

Early experiments in the development of synthetic rubber led to the invention of Silly Putty.

Natural rubber is often vulcanized, a process by which the rubber is heated and sulfur, peroxide or bisphenol are added to improve resilience and elasticity, and to prevent it from perishing. Vulcanization greatly improved the durability and utility of rubber from the 1830s on. The successful development of vulcanization is most closely associated with Charles Goodyear. Carbon black is often used as an additive to rubber to improve its strength, especially in vehicle tires.

Kottayam District of Kerala is the leader in rubber production among the states of India. The rubber plant is not a native plant of India. Dutch colonialists who also cultivated rubber in their plantations in Indonesia introduced the rubber plant to Kerala, India, because of its similar tropical climate.

Uses

The use of rubber is widespread, ranging from household to industrial products, entering the production stream at the intermediate stage or as final products. Tires and tubes are the largest consumers of rubber, accounting for around 56% total consumption in 2005. The remaining 44% are taken up by the general rubber goods (GRG) sector, which includes all products except tires and tubes.

Other significant uses of rubber are door and window profiles, hoses, belts, and dampeners for the automotive industry in what is known as the "under the bonnet" products. Gloves (medical, household and industrial) are also large consumers of rubber and toy balloons, although the type of rubber used is that of the concentrated latex. Significant tonnage of rubber is used as adhesives in many manufacturing industries and products, although the two most noticeable are the paper and the carpet industry.

Additionally, rubber produced as a fiber has significant value for use in the textile industry because of its excellent elongation and recovery properties. For these purposes, manufactured rubber fiber is made as either an extruded round fiber or rectangular fibers that are cut into strips from extruded film. Because of its low dye acceptance, its hand and appearance, the rubber fiber is either covered by yarn of another fiber or directly woven with other yarns into the fabric. In the early 1900’s, for example, rubber yarns were used in foundation garments. While rubber is still used in textile manufacturing, its low tenacity limits its use in lightweight garments because latex lacks resistance to oxidizing agents and is damaged by aging, sunlight, oil, and perspiration. Seeking a way to address these shortcomings, the textile industry has turned to Neoprene (chloroprene rubber), a type of synthetic rubber as well as another more commonly used elastomer fiber, spandex (also known as elastane), because of their superiority to rubber in both strength and durability. Rubber is also commonly used to make rubber bands and balloons, although latex can be used as well.

See also

External links

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Translations: Translations for: Rubber

Dansk (Danish)
1.
n. - gummi

idioms:

  • rubber band    elastik, gummibånd
  • rubber boot    gummistøvle
  • rubber bullet    gummikugle
  • rubber check    gummicheck, dækningsløs check
  • rubber plant    [bot.] gummitræ
  • rubber solution    [kem.] solution
  • rubber stamp    gummistempel, nikkedukke
  • rubber tree    [bot.] paragummitræ

2.
n. - rubber

Nederlands (Dutch)
rubber, overlaarzen, condoom, vlakgom, iemand/iets dat wrijft, beslissend kaartspel

Français (French)
1.
n. - caoutchouc, (GB) gomme, chiffon, (US) préservatif, capote (fam)

idioms:

  • rubber band    élastique
  • rubber boot    bottes de caoutchouc
  • rubber bullet    balle de caoutchouc
  • rubber check    (US) chèque en bois (fam)
  • rubber plant    caoutchouc
  • rubber solution    dissolution
  • rubber stamp    (lit) tampon
  • rubber tree    hévéa

2.
n. - (Sport, Jeux) partie

Deutsch (German)
1.
n. - Gummi, Kautschuk

idioms:

  • rubber band    Gummiband
  • rubber boot    Gummistiefel
  • rubber bullet    Gummigeschoß
  • rubber check    (ugs.) ungedeckter Scheck
  • rubber plant    (Bot.) Gummibaum
  • rubber solution    Gummilösung
  • rubber stamp    Gummistempel
  • rubber tree    (Bot.) Gummibaum

2.
n. - Robber

Ελληνική (Greek)
n. - ελαστικό κόμμι, καουτσούκ, γομολάστιχα, σβηστήρα, (καθομ.) προφυλακτικό, καπότα, γαλότσα
adj. - λαστιχένιος, από καουτσούκ
v. - γυρνώ να κοιτάξω, στήνω αφτί σε συζήτηση

idioms:

  • rubber band    ελαστική ταινία (κν. λαστιχάκι)
  • rubber boot    γαλότσα
  • rubber bullet    λαστιχένια σφαίρα
  • rubber check    απλήρωτη επιταγή
  • rubber plant    καουτσουκόδεντρο, εβέα
  • rubber solution    διάλυμα επισκευής λάστιχων
  • rubber stamp    (ελαστική) σφραγίδα, ο εγκρίνων τυφλά
  • rubber tree    καουτσουκόδεντρο

Italiano (Italian)
gomma, di gomma

idioms:

  • rubber band    elastico
  • rubber boot    stivali di gomma
  • rubber bullet    proiettile di gomma
  • rubber check    assegno a vuoto
  • rubber plant/tree    albero della gomma
  • rubber solution    mastice
  • rubber stamp    timbro di gomma, tirapiedi, approvazione a occhi chiusi

Português (Portuguese)
n. - borracha (f), elástico (m), camisa-de-vênus (gír.)
adj. - de borracha (f)
v. - emborrachar

idioms:

  • rubber band    elástico
  • rubber boot    botas de borracha
  • rubber bullet    balas de borracha
  • rubber check    cheque sem fundo
  • rubber plant/tree    seringueira
  • rubber solution    à base de borracha
  • rubber stamp    carimbo

Русский (Russian)
резина, ластик, резиновый, презерватив, галоша

idioms:

  • rubber band    резиновое кольцо
  • rubber boot    резиновый сапог
  • rubber bullet    резиновая пуля
  • rubber check    непокрытый чек
  • rubber plant/tree    каучуконос
  • rubber solution    жидкий каучук
  • rubber stamp    штамп

Español (Spanish)
1.
n. - goma, caucho, goma de borrar, borrador

idioms:

  • rubber band    liga elástica, cinta de goma, elástico
  • rubber boot    botas de goma
  • rubber bullet    bala de goma
  • rubber check    cheque sin fondos
  • rubber plant    ficus, gomero, árbol del caucho
  • rubber solution    solución de caucho
  • rubber stamp    sello de goma, tampón, aprobación maquinal
  • rubber tree    ficus, gomero, árbol del caucho

2.
n. - competencia que consiste en una serie de encuentros sucesivos

Svenska (Swedish)
n. - gummi, Robbert (kortspel), kondom, massör
adj. - gummi-
v. - glo, gummera

中文（简体） (Chinese (Simplified))
1. 橡胶, 橡胶制品, 合成橡胶, 橡皮套鞋

idioms:

  • rubber band    橡皮筋
  • rubber boot    防尘胶套, 高统胶鞋, 胶靴
  • rubber bullet    橡胶子弹
  • rubber check    空头支票, 退票
  • rubber plant    橡胶植物
  • rubber solution    橡胶溶液, 橡胶胶水
  • rubber stamp    橡皮图章
  • rubber tree    橡胶树

2. 三局胜负制

中文（繁體） (Chinese (Traditional))
1.
n. - 三局勝負制

2.
n. - 橡膠, 橡膠製品, 合成橡膠, 橡皮套鞋

idioms:

  • rubber band    橡皮筋
  • rubber boot    防塵膠套, 高統膠鞋, 膠靴
  • rubber bullet    橡膠子彈
  • rubber check    空頭支票, 退票
  • rubber plant    橡膠植物
  • rubber solution    橡膠溶液, 橡膠膠水
  • rubber stamp    橡皮圖章
  • rubber tree    橡膠樹

한국어 (Korean)
1.
n. - 고무, 안마, 목욕 수건

2.
n. - 세판 승부, 세 판 승부 중의 2승

日本語 (Japanese)
n. - ゴム, 天然ゴム, 消しゴム, マッサージ師, やすり, ゴム靴, 3回勝負, 2勝, 風船

idioms:

  • rubber band    ゴムバンド, 輪ゴム
  • rubber boot    ゴム靴
  • rubber bullet    ゴム弾
  • rubber check    不渡り小切手, 不渡小切手
  • rubber plant/tree    ゴムの木
  • rubber solution    ゴム液
  • rubber stamp    ゴム印, めくら判を押す人, 無批判に承認する人

العربيه (Arabic)
‏(الاسم) ممحاة, مطاط (صفه) مطاطي (فعل) يدللك‏

עברית (Hebrew)
n. - ‮גומי, כובעון (קונדום), מחק, מטלית-ניקוי, משפשף, סדרה, משחק מכריע, ערדליים, מעסה, שני נצחונות מלאים (ברידג')‬
n. - ‮סדרת תחרויות רצופה‬

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