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. Rubber tapping is the process by which Rubber is gathered An Incision is made in the bark of a Rubber tree, which cuts through the Latex The Pará rubber tree ( Hevea brasiliensis) often simply called rubber tree, is a Tree belonging to the family Euphorbiaceae In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon. A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds A colloid is a type of mechanical Mixture where one substance is dispersed evenly throughout another LaTeX (ˈleɪtɛ It can also be synthesized. The entropy model of rubber was developed in 1934 by Werner Kuhn. In Thermodynamics (a branch of Physics) entropy, symbolized by S, is a measure of the unavailability of a system ’s Energy Werner Kuhn (1899-1963 is a Swiss Physical chemist who developed the first model of the Viscosity of polymer solutions using Statistical mechanics. The scientific name for the rubber tree is Hevea brasiliensis. The Pará rubber tree ( Hevea brasiliensis) often simply called rubber tree, is a Tree belonging to the family Euphorbiaceae

Explanation

The major commercial source of natural rubber latex is the Para rubber tree, Hevea brasiliensis (Euphorbiaceae). The Pará rubber tree ( Hevea brasiliensis) often simply called rubber tree, is a Tree belonging to the family Euphorbiaceae The Spurge family ( Euphorbiaceae) is a large family of Flowering plants with 300 genera and around 7500 species 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. Sir Henry Alexander Wickham ( May 29, 1846 &ndash September 27, 1928) was an explorer author plant collector and planter The Royal Botanic Gardens Kew, usually referred to simply as Kew Gardens, are extensive Gardens and botanical glasshouses between Richmond and The seedlings were sent to Colombo, Indonesia, Singapore and British Malaya. Colombo ( Sinhala:, ˈkoləmbə Tamil: கொழும்பு is the largest city and commercial capital of Sri Lanka. The Republic of Indonesia ( (Republik Indonesia is a Country in Southeast Asia. Singapore British Malaya loosely described a set of states on the Malay Peninsula that were colonized by the British from the 18th and the 19th until the 20th century Malaya(now Malaysia) was later to become the biggest producer of rubber. Liberia and Nigeria are examples of African rubber-producing countries. Liberia, officially the Republic of Liberia, is a country on the west coast of Africa, bordered by Sierra Leone, Guinea, Côte d'Ivoire Nigeria, officially named the Federal Republic of Nigeria, is a federal Constitutional republic comprising thirty-six states and one Federal

Other plants containing latex include figs (Ficus elastica), Castilla, euphorbias, and the common dandelion. Ficus is a Genus of about 850 Species of woody Trees Shrubs Vines Epiphytes and hemi-epiphytes in the family Euphorbia is a Genus of Plants belonging to the family Euphorbiaceae. 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. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including These attempts were later supplanted by the development of synthetic rubber. Elastomer Synthetic rubber is any type of artificially made Polymer material which acts as an Elastomer.

Synthetic rubbers are made by the polymerization of a single monomer or a mixture of monomers to produce polymers. Elastomer Synthetic rubber is any type of artificially made Polymer material which acts as an Elastomer. In Polymer chemistry, polymerization is a process of reacting Monomer Molecules together in a Chemical reaction to form three-dimensional networks A monomer (from Greek mono "one" and meros "part" is a small Molecule that may become chemically bonded to other A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds These form part of a broad range of products extensively studied by polymer science and rubber technology. Polymer science or macromolecular science is the subfield of Materials science concerned with Polymers primarily synthetic polymers such as Plastics Rubber technology is the subject dealing with the transformation of Rubbers or Elastomers into useful products such as Automobile Tires The materials Examples are SBR, or styrene-butadiene rubber, BR or butadiene rubber, CR or chloroprene rubber and EPDM (ethylene-propylene-diene rubber).

History

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. Portugal, officially the Portuguese Republic (República Portuguesa is a country on the Iberian Peninsula.

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 "rubber". England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland Joseph Priestley (13 March 1733 ( Old A pencil is a Writing or Drawing instrument consisting of a thin stick of Pigment (usually Graphite, but can also be coloured pigment or

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. South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a 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 a Corporate state privately controlled by Leopold II King of the Belgians through a dummy non-governmental organization the After repeated efforts (see Henry Wickham) rubber was successfully cultivated in Southeast Asia, where it is now widely grown. Sir Henry Alexander Wickham ( May 29, 1846 &ndash September 27, 1928) was an explorer author plant collector and planter

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. India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country The first commercial Hevea plantations in India were established at Thattekadu in Kerala in 1902. Kerala ( Malayalam: {{Kerala in Malayalam}};

Properties

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. The Mullins effect is the stress-strain response in filled Rubbers which typically depends on the maximum loading previously encountered The Payne effect is a particular feature of the stress-strain behaviour of Rubber, especially rubber compounds containing Fillers such as Carbon black. A hyperelastic or Green elastic material is an ideally elastic material for which the stress-strain relationship derives from a Strain energy density function Rubber strain crystallizes. Strain Crystallization is a phenomenon in which an initially amorphous solid material undergoes a Phase transformation due to the application of strain

Owing to the presence of a double bond in each and every repeat unit, natural rubber is sensitive to ozone cracking

Chemical makeup

Aside from a few natural product impurities, natural rubber is essentially a polymer of isoprene units, a hydrocarbon diene monomer. An essential concept which defines Polymer structure the repeat unit is the simplest structural unit of a Polymer chain. Cracks can be formed in many different Elastomers by Ozone attack and the characteristic form of attack of vulnerable rubbers is known as ozone cracking. A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Isoprene is a common synonym for the chemical compound 2-methylbuta-13-diene In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon. Dienes or diolefins are Hydrocarbons which contain two double bonds. A monomer (from Greek mono "one" and meros "part" is a small Molecule that may become chemically bonded to other Synthetic rubber can be made as a polymer of isoprene or various other monomers. The material properties of natural rubber make it an elastomer and a thermoplastic. An elastomer is a Polymer with the property of Elasticity. The term which is derived from elastic polymer, is often used interchangeably with the term A thermoplastic is a Plastic that Melts to a liquid when heated and freezes to a Brittle, very Glassy state when cooled sufficiently However it should be noted that as the rubber is vulcanized it will turn into a thermoset. Thermosetting plastics thermosets are Polymer materials that irreversibly cure form 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.

Elasticity

In most elastic materials, such as metals used in springs, the elastic behavior is caused by bond distortions. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across A Coil spring, also known as a helical spring, is a mechanical device which is typically used to store energy and subsequently release it to absorb shock or to maintain A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic When force is applied, bond lengths deviate from the (minimum energy) equilibrium and strain energy is stored electrostatically. At a point in space the electric potential is the Potential energy per unit of charge that is associated with a static (time-invariant Electric field 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. Thermal energy is the sum of the sensible energy and latent energy.

In its relaxed state rubber consists of long, coiled-up polymer chains that are interlinked at a few points. In Chemistry, a disulfide bond is a single Covalent bond derived from the coupling of Thiol groups 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. Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed The kinetic energy of an object is the extra Energy which it possesses due to its motion

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. In Thermodynamics (a branch of Physics) entropy, symbolized by S, is a measure of the unavailability of a system ’s Energy 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. A rubber band (in some regions known as a binder, elastic band, lackey band, elastic blubber, "laggy band" or gumband') Rubber relaxation is endothermic, and for this reason the force exerted by a stretched piece of rubber increases with temperature (metals, for example, become softer as temperature increases). In Thermodynamics, the word endothermic "within-heating" describes a process or reaction that absorbs Energy in the form of Heat. The material undergoes adiabatic cooling during contraction. This article covers adiabatic processes in Thermodynamics. For adiabatic processes in Quantum mechanics, see Adiabatic process (quantum mechanics 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. These four properties that constitute an ideal gas can be easily remembered by the acronym RIPE which stands for - R andom Motion (molecules are in constant random motion Note that a compressed gas also exhibits "elastic" properties, for instance inside an inflated car tire. This article is about tires used on road Vehicles including pneumatic tires and solid tires. 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 disulfide bonds between chains so it makes each free section of chain shorter. Vulcanization (or Vulcanisation refers to a specific curing process of Rubber involving high heat and the addition of Sulfur or other equivalent curatives In Chemistry, a disulfide bond is a single Covalent bond derived from the coupling of Thiol groups 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. The glass transition temperature, T g is the temperature at which an Amorphous solid, such as Glass or a Polymer, becomes brittle 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. This article is about tires used on road Vehicles including pneumatic tires and solid 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. An o-ring, also known as a packing or a toric joint, is a mechanical Gasket in the shape of a Torus; it is a loop of Elastomer with The Space Shuttle Challenger disaster took place on January 28 1986 when ''Challenger'', a Space Shuttle operated by NASA, broke apart The disaster happened on an unusually cold day.

Current sources

Close to 21 million tons of rubber were produced in 2005 of which around 42% was natural. Since bulk of the rubber produced is the synthetic variety which is derived from petroleum, the price of even natural rubber is determined to a very large extent by the prevailing global price of crude oil. 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.

Cultivation

A tree woman in Sri Lanka in the process of harvesting rubber. Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka ( Sinhalese:, இலங்கை known as Ceylon before 1972 is an Island

Rubber latex is extracted from Rubber trees. The economic life period of rubber trees in plantations is around 32 years – 7 years of immature phase and about 25 years of productive phase.

The soil requirement of the plant is generally well-drained weathered soil consisting of laterite, lateritic types, sedimentary types, nonlateritic red or alluvial soils.

The climatic conditions for optimum growth of Rubber tree consist of (a) Rainfall of around 250 cm evenly distributed without any marked dry season and with at least 100 rainy days per annum (b) Temperature range of about 20oC to 34oC with a monthly mean of 25 to 28oC (c) High atmospheric humidity of around 80% (d) Bright sunshine amounting to about 2000 hours per annum at the rate of 6 hours per day throughout the year and (e) Absence of strong winds.

Many high yielding clones have been developed for Rubber plantation. These clones yield more than 1,500 Kilogrammes of dry Rubber per hectare per annum, when grown in good conditions.

Collection

In places like Kerala, where coconuts are in abundance, the shell of half a coconut is used as the collection container for the latex. Kerala ( Malayalam: {{Kerala in Malayalam}}; 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. Formic acid (systematically called methanoic acid) is the simplest Carboxylic acid. 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. Vulcanization (or Vulcanisation refers to a specific curing process of Rubber involving high heat and the addition of Sulfur or other equivalent curatives

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, matting, flooring and dampeners (anti-vibration mounts) for the automotive industry in what is known as the "under the bonnet" products. The automotive industry is the industry involved in the design development manufacture marketing and sale of Motor vehicles In 2007 more than 73 million motor vehicles 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. A glove ( Middle English from Old English glof) is a type of Garment (and more specifically a Fashion 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. Glue or adhesive is a compound that adheres or bonds two items together Manufacturing (from Latin manu factura, "making by hand" is the use of tools and labor to make things for use or sale A carpet is any loom-woven felted textile or grass floor covering Rubber is also commonly used to make rubber bands and pencil erasers. A rubber band (in some regions known as a binder, elastic band, lackey band, elastic blubber, "laggy band" or gumband') An eraser or rubber is an article of Stationery that is used for removing Pencil and sometimes Pen writings

Additionally, rubber produced as a fiber sometimes called elastic, 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, feel 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 (polymer form of Chloroprene), 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. Neoprene or polychloroprene is a family of synthetic Rubbers that are produced by Polymerization of Chloroprene. Chloroprene is the common name for the Organic compound 2-chloro-13-butadiene, which has the Chemical formula CH2=CCl-CH=CH2 Spandex or elastane is a Synthetic fiber known for its exceptional elasticity.

Hypoallergenic rubber can be made from Guayule. Hypoallergenic is a term coined by advertisers (based on the Greek prefix Hypo meaning "below normal" or "slightly" and first used in a cosmetics Parthenium argentatum, commonly known as Guayule (/gwɑː'juː

Early experiments in the development of synthetic rubber also led to the invention of Silly Putty. Elastomer Synthetic rubber is any type of artificially made Polymer material which acts as an Elastomer. Silly Putty (originally called Nutty Putty, and also marketing by other companies as Thinking Putty, Bouncing Putty) is the Crayola owned trademark

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 (or Vulcanisation refers to a specific curing process of Rubber involving high heat and the addition of Sulfur or other equivalent curatives Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Vulcanization (or Vulcanisation refers to a specific curing process of Rubber involving high heat and the addition of Sulfur or other equivalent curatives 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. Charles Goodyear ( December 29, 1800 - July 1, 1860) was the first American to vulcanize rubber, a process which he discovered in Carbon black is often used as an additive to rubber to improve its strength, especially in vehicle tires. Carbon black is a material produced by the incomplete Combustion of heavy Petroleum products such as FCC tar coal tar ethylene cracking tar and a small amount from

See also

References

Rubbery Materials and their Compounds by J. Akron is a city in the US state of Ohio and the County seat of Summit County. Charles Goodyear ( December 29, 1800 - July 1, 1860) was the first American to vulcanize rubber, a process which he discovered in Charles H Greville Williams ( September 22, 1829 - June 15, 1910) was an English Scientist and analytical Chemist who An elastomer is a Polymer with the property of Elasticity. The term which is derived from elastic polymer, is often used interchangeably with the term Fordlândia ("Ford-land" was a vast tract of land purchased by American automobile tycoon Henry Ford in the 1920s LaTeX (ˈleɪtɛ Cracks can be formed in many different Elastomers by Ozone attack and the characteristic form of attack of vulnerable rubbers is known as ozone cracking. Rubber tapping is the process by which Rubber is gathered An Incision is made in the bark of a Rubber tree, which cuts through the Latex The Stevenson Plan was an effort by the British government to stabilize low rubber prices resulting from a glut of rubber following World War I. Elastomer Synthetic rubber is any type of artificially made Polymer material which acts as an Elastomer. A Brydson

Rubber Technology by Maurice Morton

External links

• International Rubber Research & Development Board
• History of the International Rubber Industry from 1870-1930 from EH.NET
• Malaysian Rubber Board
• Rubber Board Of India
• Rubber Division of ACS
• Rubber timeline
• Stop Firestone's Use of Child Labor in Rubber Production