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96-455: Neoprene is produced by free-radical polymerization of chloroprene . In commercial production, this polymer is prepared by free radical emulsion polymerization . Polymerization is initiated using potassium persulfate . Bifunctional nucleophiles, metal oxides (e.g. zinc oxide), and thioureas are used to crosslink individual polymer strands. Neoprene was invented by DuPont scientists on April 17, 1930, after Elmer K. Bolton of DuPont attended

192-487: A 7 mm neoprene wet suit offers much less exposure protection under 100 feet of water than at the surface. A recent advance in neoprene for wet suits is the "super-flex" variety, which uses spandex in the knit liner fabric for greater flexibility and stretch. A drysuit is similar to a wetsuit, but uses thicker and more durable neoprene to create an entirely waterproof suit that is suitable for wear in extremely cold water or polluted water. Recently, neoprene has become

288-422: A base for adhesives , noise isolation in power transformer installations, and as padding in external metal cases to protect the contents while allowing a snug fit. It resists burning better than exclusively hydrocarbon based rubbers, resulting in its appearance in weather stripping for fire doors and in combat related attire such as gloves and face masks. Because of its tolerance of extreme conditions, neoprene

384-469: A category 3 fire hazard (ignition under the presence of moderate heat), and a category 1 reactivity (unstable at high temperatures and pressures). Chronic exposure to chloroprene may have the following symptoms: liver function abnormalities, disorders of the cardiovascular system, and depression of the immune system. The Environmental Protection Agency designated chloroprene as likely to be carcinogenic to humans based on evidence from studies that showed

480-596: A favorite material for lifestyle and other home accessories including laptop sleeves, tablet holders, remote controls , mouse pads , and cycling chamois. The Rhodes piano used hammer tips made of neoprene in its electric pianos, after changing from felt hammers around 1970. Neoprene is also used for speaker cones and drum practice pads. Hydroponic and aerated gardening systems make use of small neoprene inserts to hold plants in place while propagating cuttings or using net cups. Inserts are relatively small, ranging in size from 1.5 to 5 inches (4 to 13 cm). Neoprene

576-447: A fiber, sometimes called 'elastic', had significant value to the textile industry because of its excellent elongation and recovery properties. For these purposes, manufactured rubber fiber was made as either an extruded round fiber or rectangular fibers cut into strips from extruded film. Because of its low dye acceptance, feel and appearance, the rubber fiber was either covered by yarn of another fiber or directly woven with other yarns into

672-510: A form of assisted biological coagulation. Little care is taken to exclude twigs, leaves, and even bark from the lumps that are formed, which may also include tree lace. Earth scrap is material that gathers around the base of the tree. It arises from latex overflowing from the cut and running down the bark, from rain flooding a collection cup containing latex, and from spillage from tappers' buckets during collection. It contains soil and other contaminants, and has variable rubber content, depending on

768-752: A given strain, thereby increasing the elastic force constant and making the rubber harder and less extensible. Raw rubber storage depots and rubber processing can produce malodour that is serious enough to become a source of complaints and protest to those living in the vicinity. Microbial impurities originate during the processing of block rubber. These impurities break down during storage or thermal degradation and produce volatile organic compounds. Examination of these compounds using gas chromatography / mass spectrometry (GC/MS) and gas chromatography (GC) indicates that they contain sulfur, ammonia, alkenes , ketones , esters , hydrogen sulfide , nitrogen, and low-molecular-weight fatty acids (C2–C5). When latex concentrate

864-795: A lecture by Fr Julius Arthur Nieuwland , a professor of chemistry at the University of Notre Dame . Nieuwland's research was focused on acetylene chemistry and during the course of his work he produced divinyl acetylene, a jelly that firms into an elastic compound similar to rubber when passed over sulfur dichloride . After DuPont purchased the patent rights from the university, Wallace Carothers of DuPont took over commercial development of Nieuwland's discovery in collaboration with Nieuwland himself and DuPont chemists Arnold Collins , Ira Williams and James Kirby. Collins focused on monovinyl acetylene and allowed it to react with hydrogen chloride gas, manufacturing chloroprene . DuPont first marketed

960-577: A marketing strategy that included publishing its own technical journal, which extensively publicized neoprene's uses as well as advertising other companies' neoprene-based products. By 1939, sales of neoprene were generating profits over $ 300,000 for the company (equivalent to $ 6,600,000 in 2023). The high tensile performance of neoprene is a result of its highly regular backbone structure, which causes neoprene to undergo strain crystallization under tensile loading. A two parameter (strain rate and temperature) hyperelastic model can accurately capture much of

1056-438: A neoprene- spandex mixture for manufacture of wheelchair positioning harnesses. In tabletop wargames, neoprene mats printed with grassy, sandy, icy, or other natural features have become popular gaming surfaces. They are durable, firm and stable, and attractive in appearance, and also favoured for their ability to roll up in storage but lie flat when unrolled. Because of its chemical resistance and overall durability, neoprene

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1152-432: A petroleum refinery or other natural incineration processes, is sometimes used as an additive to rubber to improve its strength, especially in vehicle tires. During vulcanization, rubber's polyisoprene molecules (long chains of isoprene) are heated and cross-linked with molecular bonds to sulfur, forming a 3-D matrix. The optimal percentage of sulfur is approximately 10%. In this form, the polyisoprene molecules orientation

1248-506: A piece of the material was extremely good for rubbing off pencil marks on paper, hence the name "rubber". It slowly made its way around England. In 1764, François Fresnau discovered that turpentine was a rubber solvent . Giovanni Fabbroni is credited with the discovery of naphtha as a rubber solvent in 1779. Charles Goodyear redeveloped vulcanization in 1839, although Mesoamericans had used stabilized rubber for balls and other objects as early as 1600 BC. South America remained

1344-435: A point where it shares properties of both; i.e., if it is heated and cooled, it is degraded but not destroyed. The final properties of a rubber item depend not just on the polymer, but also on modifiers and fillers, such as carbon black , factice , whiting and others. Rubber particles are formed in the cytoplasm of specialized latex-producing cells called laticifers within rubber plants. Rubber particles are surrounded by

1440-410: A revision of EPA’s 2010 assessment of the chemical, arguing that the model used to estimate human cancer risk based on experiments, performed on mice, was not rigorous. Only stabilized chloroprene can be transported in U.S.. Chloroprene, if inhaled in any amount over 1ppm is toxic to the human body. Chloroprene is carcinogenic, can cause temporary hair loss on the exposed area, and can cause damage to

1536-451: A significant amount of rubber. Gloves (medical, household, and industrial) and toy balloons were large consumers of rubber, although the type of rubber used is concentrated latex. Significant tonnage of rubber was used as adhesives in many manufacturing industries and products, although the two most noticeable were the paper and the carpet industries. Rubber was commonly used to make rubber bands and pencil erasers . Rubber produced as

1632-453: A single phospholipid membrane with hydrophobic tails pointed inward. The membrane allows biosynthetic proteins to be sequestered at the surface of the growing rubber particle, which allows new monomeric units to be added from outside the biomembrane, but within the lacticifer. The rubber particle is an enzymatically active entity that contains three layers of material, the rubber particle, a biomembrane and free monomeric units. The biomembrane

1728-506: A statistically significant association between occupational chloroprene exposure and the risk of lung cancer. As early as 1975, NIOSH had identified the potential health hazards of chloroprene in their bulletin primarily citing two Russian cohort studies from those working with chloroprene in an occupational setting. Several epidemiological studies and toxicological reports provide evidence of chloroprene's capability to inflict occupational health and safety concerns. However, varying reviews of

1824-401: A wire that encircles the tree. This wire incorporates a spring so it can stretch as the tree grows. The latex is led into the cup by a galvanised "spout" knocked into the bark. Rubber tapping normally takes place early in the morning, when the internal pressure of the tree is highest. A good tapper can tap a tree every 20 seconds on a standard half-spiral system, and a common daily "task" size

1920-406: Is 1-chlorobuta-1,3-diene, which is usually separated by distillation . Until the 1960s, chloroprene production was dominated by the "acetylene process," which was modeled after the original synthesis of vinylacetylene . In this process, acetylene is dimerized to give vinyl acetylene, which is then combined with hydrogen chloride to afford 4-chloro-1,2-butadiene (an allene derivative), which in

2016-442: Is 25 cm (vertical) bark consumption per year. The latex-containing tubes in the bark ascend in a spiral to the right. For this reason, tapping cuts usually ascend to the left to cut more tubes. The trees drip latex for about four hours, stopping as latex coagulates naturally on the tapping cut, thus blocking the latex tubes in the bark. Tappers usually rest and have a meal after finishing their tapping work and then start collecting

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2112-517: Is a colorless volatile liquid, almost exclusively used as a monomer for the production of the polymer polychloroprene, better known as neoprene , a type of synthetic rubber . Although it may have been discovered earlier, chloroprene was largely developed by DuPont during the early 1930s, specifically with the formation of neoprene in mind. The chemists Elmer K. Bolton , Wallace Carothers , Arnold Collins and Ira Williams are generally accredited with its development and commercialisation although

2208-457: Is a good choice for supporting plants because of its flexibility and softness, allowing plants to be held securely in place without the chance of causing damage to the stem. Neoprene root covers also help block out light from entering the rooting chamber of hydroponic systems, allowing for better root growth and helping to deter the growth of algae. During the COVID-19 global pandemic, neoprene

2304-418: Is a natural polymer of isoprene (polyisoprene), and an elastomer (a stretchy polymer). Polymers are simply chains of molecules that can be linked together. Rubber is one of the few naturally occurring polymers and prized for its high stretch ratio, resilience, and water-proof properties. Other examples of natural polymers include tortoise shell , amber , and animal horn . When harvested, latex rubber takes

2400-416: Is a popular material in making protective clothing for aquatic activities. Foamed neoprene is commonly used to make fly fishing waders, wetsuits , and drysuits as it provides excellent insulation against cold. The foam is quite buoyant, and divers compensate for this by wearing weights. Since foam neoprene contains gas pockets, the material compresses under water pressure, getting thinner at greater depths;

2496-414: Is a result of the competing factors of scission of the main polymer chain and oxidative cross-linking. Chain scission leads to degradation, embrittlement , and a loss of toughness. Oxidation reactions in the presence of heating leads to increased cross-linking, which in turn causes hardening. The interplay of both these factors determines the resulting effect on material mechanical properties; cross-linking

2592-573: Is also advised that grounded and bonded metal containers are used for the transport of chloroprene. A table of occupational exposure limits (OELs) from various jurisdictions follows. In general, the OELs range from 0.55 ppm to 25 ppm. In the ACGIH's 2018 TLV and BEI booklet , chloroprene was designated with a skin and an A2 notation. The skin notation designation is based on animal and human research that have shown chloroprene's ability to be absorbed by

2688-415: Is between 450 and 650 trees. Trees are usually tapped on alternate or third days, although many variations in timing, length and number of cuts are used. "Tappers would make a slash in the bark with a small hatchet. These slanting cuts allowed latex to flow from ducts located on the exterior or the inner layer of bark ( cambium ) of the tree. Since the cambium controls the growth of the tree, growth stops if it

2784-472: Is classified as a polytropic poison, and it causes organic disturbances in the nervous system and cardiovascular system. Examinations of the cardiovascular system show muffled heart sounds, reduced arterial pressure, and tachycardia. Within exposed workers, they report respiratory problems, eye and skin irritation, chest pains, and neurological symptoms. The fate of chloroprene in the environment has been examined. Due to its volatility and extreme reactivity, it

2880-496: Is cut. Thus, rubber tapping demanded accuracy, so that the incisions would not be too many given the size of the tree, or too deep, which could stunt its growth or kill it." It is usual to tap a panel at least twice, sometimes three times, during the tree's life. The economic life of the tree depends on how well the tapping is carried out, as the critical factor is bark consumption. A standard in Malaysia for alternate daily tapping

2976-555: Is harvested mainly in the form of the latex from the Pará rubber tree ( Hevea brasiliensis ) or others. The latex is a sticky, milky and white colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called "tapping". The latex then is refined into the rubber that is ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for sale. Natural rubber

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3072-438: Is held tightly to the rubber core by the high negative charge along the double bonds of the rubber polymer backbone. Free monomeric units and conjugated proteins make up the outer layer. The rubber precursor is isopentenyl pyrophosphate (an allylic compound), which elongates by Mg -dependent condensation by the action of rubber transferase. The monomer adds to the pyrophosphate end of the growing polymer. The process displaces

3168-412: Is in hazard class 3 (flammable liquid). Its UN number is 1991 and is in packing group 1. Chloroprene is toxic. It is reactive towards air, producing peroxides, which are also toxic. Handling of and exposure to chloroprene poses an occupational health risk to workers involved in the manufacture and production of neoprene. As a way to visually communicate hazards associated with chloroprene exposure,

3264-572: Is low and strain results from small changes of bond lengths and angles: this caused the Challenger disaster , when the American Space Shuttle 's flattened o-rings failed to relax to fill a widening gap. The glass transition is fast and reversible: the force resumes on heating. The parallel chains of stretched rubber are susceptible to crystallization. This takes some time because turns of twisted chains have to move out of

3360-437: Is manufactured by foaming the rubber with nitrogen gas, where the tiny enclosed and separated gas bubbles can also serve as insulation. Nitrogen gas is most commonly used for the foaming of neoprene foam due to its inertness, flame resistance, and large range of processing temperatures. Neoprene is used as a component of elastomeric bridge bearings , to support heavy loads while permitting small horizontal movements. Neoprene

3456-899: Is not cultivated widely in its native continent of South America because of the South American leaf blight , and other natural predators there. Rubber latex is extracted from rubber trees. The economic life of rubber trees in plantations is around 32 years, with up to 7 years being an immature phase and about 25 years of productive phase. The soil requirement is well-drained, weathered soil consisting of laterite , lateritic types, sedimentary types, nonlateritic red or alluvial soils. The climatic conditions for optimum growth of rubber trees are: Many high-yielding clones have been developed for commercial planting. These clones yield more than 2,000 kilograms per hectare (1,800 lb/acre) of dry rubber per year, under ideal conditions. Rubber production has been linked to deforestation. Rubber therefore

3552-404: Is not expected to bioaccumulate. The only known environmental effect is related to how chloroprene is volatile and spreads rapidly through the air. This highly flammable component increases the possibility of causing a fire or explosion releasing irritating or toxic fumes (or gases). In 2022, a request made by Denka to regulate chloroprene emissions was rejected by EPA. The request establishes

3648-432: Is of interest in the devulcanization process Finally, ultraviolet radiation is seen to decrease the mechanical properties of neoprene, which is important for outdoors applications of neoprene. Neoprene resists degradation more than natural or synthetic rubber . This relative inertness makes neoprene well suited for demanding applications such as gaskets , hoses , and corrosion -resistant coatings . It can be used as

3744-588: Is one of seven commodities included in the 2023 EU Regulation on Deforestation-free products (EUDR), which aims to guarantee that the products European Union (EU) citizens consume do not contribute to deforestation or forest degradation worldwide. In places such as Kerala and Sri Lanka, where coconuts are in abundance, the half shell of coconut was used as the latex collection container. Glazed pottery or aluminium or plastic cups became more common in Kerala-India and other countries. The cups are supported by

3840-449: Is produced by smallholders, who collect rubber from trees far from the nearest factory. Many Indonesian smallholders, who farm paddies in remote areas, tap dispersed trees on their way to work in the paddy fields and collect the latex (or the coagulated latex) on their way home. As it is often impossible to preserve the latex sufficiently to get it to a factory that processes latex in time for it to be used to make high quality products, and as

3936-529: Is produced from rubber, sulfuric acid is used for coagulation. This produces malodourous hydrogen sulfide. The industry can mitigate these bad odours with scrubber systems . Rubber is the polymer cis-1,4-polyisoprene – with a molecular weight of 100,000 to 1,000,000 daltons . Typically, a small percentage (up to 5% of dry mass) of other materials, such as proteins , fatty acids , resins , and inorganic materials (salts) are found in natural rubber. Polyisoprene can also be created synthetically, producing what

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4032-402: Is sometimes referred to as "synthetic natural rubber", but the synthetic and natural routes are distinct. Some natural rubber sources, such as gutta-percha , are composed of trans-1,4-polyisoprene, a structural isomer that has similar properties. Natural rubber is an elastomer and a thermoplastic . Once the rubber is vulcanized, it is a thermoset . Most rubber in everyday use is vulcanized to

4128-520: Is sometimes used in the manufacture of dishwashing gloves, especially as an alternative to latex . In fashion, neoprene has been used by designers such as Gareth Pugh , Balenciaga , Rick Owens , Lanvin , and Vera Wang . Neoprene was also used as an experimental fabric to upholster a mirror by designer Flavia Brilli for her mirror brand Jazz Frames . Some people are allergic to neoprene while others can get dermatitis from thiourea residues left from its production. The most common accelerator in

4224-479: Is still random but they become aligned when the rubber is stretched. This sulfur vulcanization makes the rubber stronger and more rigid, but still very elastic. And through the vulcanization process, the sulfur and latex are meant to be totally used up in individual form. Natural rubber latex is shipped from factories in Southeast Asia , South America , and West and Central Africa to destinations around

4320-431: Is subsequently isomerized to 3,4 isomer, which in turn is treated with base to induce dehydrochlorination to 2-chlorobuta-1,3-diene. This dehydrohalogenation entails loss of a hydrogen atom in the 3 position and the chlorine atom in the 4 position thereby forming a double bond between carbons 3 and 4. In 1983, approximately 2,000,000 kg was produced in this manner. The chief impurity in chloroprene prepared in this way

4416-467: Is the Amazonian rubber tree ( Hevea brasiliensis ), a member of the spurge family , Euphorbiaceae . Once native to Brazil, the species is now pan-tropical. This species is preferred because it grows well under cultivation. A properly managed tree responds to wounding by producing more latex for several years. Congo rubber , formerly a major source of rubber, which motivated the atrocities in

4512-500: Is thought to dominate for neoprene. As neoprene is used to make electric cable jackets in nuclear power plants, the effect of gamma radiation on the mechanical properties of neoprene has also been investigated. Chain scission, possibly triggered by free radicals from irradiated oxygen, is seen to deteriorate the mechanical properties of neoprene. Likewise, the tensile strength, hardness, and ultimate elongation of neoprene can also be degraded upon exposure to microwave radiation , which

4608-474: Is used extensively in many applications and products, either alone or in combination with other materials. In most of its useful forms, it has a large stretch ratio and high resilience and also is buoyant and water-proof. Industrial demand for rubber-like materials began to outstrip natural rubber supplies by the end of the 19th century, leading to the synthesis of synthetic rubber in 1909 by chemical means. The major commercial source of natural rubber latex

4704-447: Is used to line landfills. Neoprene's burn point is around 260 °C (500 °F). In its native state, neoprene is a very pliable rubber-like material with insulating properties similar to rubber or other solid plastics. Neoprene foam is used in many applications and is produced in either closed-cell or open-cell form. The closed-cell form is waterproof , less compressible and more expensive. The open-cell form can be breathable . It

4800-601: The Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) in Germany developed a cultivar of the Kazakh dandelion ( Taraxacum kok-saghyz ) that is suitable for commercial production of natural rubber. In collaboration with Continental Tires , IME began a pilot facility. Many other plants produce forms of latex rich in isoprene polymers, though not all produce usable forms of polymer as easily as

4896-505: The Mullins effect and the Payne effect and is often modeled as hyperelastic . Rubber strain crystallizes . Because there are weakened allylic C-H bonds in each repeat unit , natural rubber is susceptible to vulcanisation as well as being sensitive to ozone cracking . The two main solvents for rubber are turpentine and naphtha (petroleum). Because rubber does not dissolve easily,

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4992-728: The Putumayo genocide . Between the 1880s–1913 Julio César Arana and his company that would become the Peruvian Amazon Company controlled the Putumayo river. W.E. Hardenburg, Benjamin Saldaña Rocca and Roger Casement were influential figures in exposing these atrocities. Roger Casement was also prominent in revealing the Congo atrocities to the world. Days before entering Iquitos by boat Casement wrote "'Caoutchouc

5088-557: The cytosol . In plants, isoprene pyrophosphate can also be obtained from the 1-deox-D-xyulose-5-phosphate/2-C-methyl-D-erythritol-4-phosphate pathway within plasmids. The relative ratio of the farnesyl pyrophosphate initiator unit and isoprenyl pyrophosphate elongation monomer determines the rate of new particle synthesis versus elongation of existing particles. Though rubber is known to be produced by only one enzyme, extracts of latex host numerous small molecular weight proteins with unknown function. The proteins possibly serve as cofactors, as

5184-481: The vulcanization of polychloroprene is ethylene thiourea (ETU), which has been classified as a reproductive toxin . From 2010 to 2013, the European rubber industry had a research project titled SafeRubber to develop a safer alternative to the use of ETU. Chloroprene Chloroprene ( IUPAC name 2-chlorobuta-1,3-diene ) is a chemical compound with the molecular formula CH 2 =CCl−CH=CH 2. Chloroprene

5280-673: The Congo Free State for more information on the rubber trade in the Congo Free State in the late 1800s and early 1900s.) The rubber boom in the Amazon also similarly affected indigenous populations to varying degrees. Correrias, or slave raids were frequent in Colombia, Peru and Bolivia where many were either captured or killed. The most well known case of atrocities generated from rubber extraction in South America came from

5376-534: The Congo Free State , came from vines in the genus Landolphia ( L. kirkii , L. heudelotis , and L. owariensis ). Dandelion milk contains latex. The latex exhibits the same quality as the natural rubber from rubber trees . In the wild types of dandelion, latex content is low and varies greatly. In Nazi Germany , research projects tried to use dandelions as a base for rubber production, but failed. In 2013, by inhibiting one key enzyme and using modern cultivation methods and optimization techniques, scientists in

5472-565: The Pará. Some of them require more elaborate processing to produce anything like usable rubber, and most are more difficult to tap. Some produce other desirable materials, for example gutta-percha ( Palaquium gutta ) and chicle from Manilkara species. Others that have been commercially exploited, or at least showed promise as rubber sources, include the rubber fig ( Ficus elastica ), Panama rubber tree ( Castilla elastica ), various spurges ( Euphorbia spp.), lettuce ( Lactuca species),

5568-583: The United Nations Globally Harmonized System of Classification and Labeling of Chemicals has designated the following hazards for exposure to chloroprene: flammable, toxic, dangerous to the environment, health hazard and irritant. Chloroprene poses fire hazard (flash point −4 °F (−20 °C)). OSHA identifies chloroprene as a category 2 flammable liquid and emphasizes that at least one portable fire extinguisher should be within 10 and no more than 25 feet away from

5664-409: The amount of contaminants. Earth scrap is collected by field workers two or three times a year and may be cleaned in a scrap-washer to recover the rubber, or sold to a contractor who cleans it and recovers the rubber. It is of low quality. Latex coagulates in the cups if kept for long and must be collected before this happens. The collected latex, "field latex", is transferred into coagulation tanks for

5760-410: The compound in 1931 under the trade name DuPrene, but its commercial possibilities were limited by the original manufacturing process, which left the product with a foul odor. A new process was developed, which eliminated the odor-causing byproducts and halved production costs, and the company began selling the material to manufacturers of finished end-products. To prevent shoddy manufacturers from harming

5856-415: The degree to which chloroprene should be held responsible for health concerns highlight the criticality of sound scientific research. Only one fatality as a result of chloroprene intoxication has been recorded which was a result of cleaning a container used for chloroprene. The primary occupational concern for chloroprene is limited to the facilities producing chloroprene and using chloroprene to produce

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5952-407: The dry rubber produced. Latex that drips onto the ground, "earth scrap", is also collected periodically for processing of low-grade product. Cup lump is the coagulated material found in the collection cup when the tapper next visits the tree to tap it again. It arises from latex clinging to the walls of the cup after the latex was last poured into the bucket, and from late-dripping latex exuded before

6048-488: The eyes and skin. Natural rubber Rubber , also called India rubber , latex , Amazonian rubber , caucho , or caoutchouc , as initially produced, consists of polymers of the organic compound isoprene , with minor impurities of other organic compounds. Thailand , Malaysia , Indonesia , and Cambodia are four of the leading rubber producers. Types of polyisoprene that are used as natural rubbers are classified as elastomers . Currently, rubber

6144-636: The fabric. 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. The textile industry turned to neoprene (polymer 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. Rubber exhibits unique physical and chemical properties. Rubber's stress–strain behavior exhibits

6240-477: The first technique for tapping trees for latex without causing serious harm to the tree. Because of his fervent promotion of this crop, he is popularly remembered by the nickname "Mad Ridley". Before World War II significant uses included door and window profiles, hoses, belts, gaskets, matting , flooring, and dampeners (antivibration mounts) for the automotive industry. The use of rubber in car tires (initially solid rather than pneumatic) in particular consumed

6336-512: The flammable liquid storage area. OSHA provides resources on addressing flammable liquids at industrial plants which is where the likely exposure to chloroprene exists (see external resources). As a vapor, chloroprene is heavier than air. According to the National Fire Protection Association 's rating system, chloroprene is designated with a category 2 health hazard (temporary incapacitation or residual injury),

6432-544: The form of latex, an opaque, white, milky suspension of rubber particles in water. It is then transformed through industrial processes to the solid form widely seen in manufactured goods. Natural rubber is reactive and vulnerable to oxidization, but it can be stabilized through a heating process called vulcanization. Vulcanization is a process by which the rubber is heated and sulfur , peroxide , or bisphenol are added to improve resistance and elasticity and to prevent it from oxidizing. Carbon black , which can be derived from

6528-459: The higher-grade, technically specified block rubbers such as SVR 3L or SVR CV or used to produce Ribbed Smoke Sheet grades. Naturally coagulated rubber (cup lump) is used in the manufacture of TSR10 and TSR20 grade rubbers. Processing for these grades is a size reduction and cleaning process to remove contamination and prepare the material for the final stage of drying. The dried material is then baled and palletized for storage and shipment. Rubber

6624-431: The international market spot price of a seemingly more profitable crop (for example palm oil ) surges in relation to rubber. For instance, during the 2020 and 2021 international COVID-19 pandemic , demand for rubber gloves surged, leading to a spike in rubber prices of about 30%. In addition to the pandemic, demand exceeded supply in part because long term plantations had been torn out and replaced with other crops over

6720-532: The latex sap. Charles Marie de La Condamine is credited with introducing samples of rubber to the Académie Royale des Sciences of France in 1736. In 1751, he presented a paper by François Fresneau to the Académie (published in 1755) that described many of rubber's properties. This has been referred to as the first scientific paper on rubber. In England, Joseph Priestley , in 1770, observed that

6816-402: The latex would anyway have coagulated by the time it reached the factory, the smallholder will coagulate it by any means available, in any container available. Some smallholders use small containers, buckets etc., but often the latex is coagulated in holes in the ground, which are usually lined with plastic sheeting. Acidic materials and fermented fruit juices are used to coagulate the latex –

6912-434: The latex-carrying vessels of the tree become blocked. It is of higher purity and of greater value than the other three types. 'Cup lumps' can also be used to describe a completely different type of coagulate that has collected in smallholder plantations over a period of 1–2 weeks. After tapping all of the trees, the tapper will return to each tree and stir in some type of acid, which allows the newly harvested latex to mix with

7008-416: The latex. There is growing concern for the future supply of rubber due to various factors, including plant disease, climate change, and the volatile market price of rubber. Producers of natural rubber are mostly small family-held plantations, often serving large industrial aggregators. High volatility in the price of rubber affects rubber plantation investment, and farmers may remove their rubber trees if

7104-443: The liquid "field latex" at about midday. The four types of field coagula are "cuplump", "treelace", "smallholders' lump", and "earth scrap". Each has significantly different properties. Some trees continue to drip after the collection leading to a small amount of "cup lump" that is collected at the next tapping. The latex that coagulates on the cut is also collected as "tree lace". Tree lace and cup lump together account for 10%–20% of

7200-528: The main source of latex rubber used during much of the 19th century. The rubber trade was heavily controlled by business interests but no laws expressly prohibited the export of seeds or plants. In 1876, Henry Wickham smuggled 70,000 Amazonian rubber tree seeds from Brazil and delivered them to Kew Gardens , England. Only 2,400 of these germinated. Seedlings were then sent to India , British Ceylon ( Sri Lanka ), Dutch East Indies ( Indonesia ), Singapore , and British Malaya . Malaya (now Peninsular Malaysia )

7296-399: The material is finely divided by shredding prior to its immersion. An ammonia solution can be used to prevent the coagulation of raw latex. Rubber begins to melt at approximately 180 °C (356 °F). On a microscopic scale, relaxed rubber is a disorganized cluster of erratically changing wrinkled chains. In stretched rubber, the chains are almost linear. The restoring force is due to

7392-409: The mechanical response of neoprene. Exposure to acetone and heat have been shown to degrade the tensile strength and ultimate elongation of neoprene, likely due to a loss of plasticizers as well as an increase in crosslinking during heat exposure. The response of neoprene to thermal aging depends not just on the highest temperature it is exposed to, but also on the exact temperature-time profile; this

7488-558: The occupational setting. Chloroprene should be stored in closed containers in a cool, well-ventilated area with the temperature no higher than 50 °F (10 °C). In addition, chloroprene has a high reactivity and should be stored away from oxidizing agents such as perchlorate, peroxides, permanganates, chlorates, nitrates, chlorine, bromine, and fluorine. All activities inducing a potential fire hazard should be avoided. For instance, smoking, having open flames or using sparking tools to open or close storage containers should be prohibited. It

7584-577: The plantation expanded to Karnataka , Tamil Nadu and the Andaman and Nicobar Islands of India. Today, India is the world's 3rd largest producer and 4th largest consumer of rubber. In Singapore and Malaya, commercial production was heavily promoted by Sir Henry Nicholas Ridley , who served as the first Scientific Director of the Singapore Botanic Gardens from 1888 to 1911. He distributed rubber seeds to many planters and developed

7680-606: The preparation of dry rubber or transferred into air-tight containers with sieving for ammoniation. Ammoniation, invented by patent lawyer and vice-president of the United States Rubber Company Ernest Hopkinson around 1920, preserves the latex in a colloidal state for longer periods of time. Latex is generally processed into either latex concentrate for manufacture of dipped goods or coagulated under controlled, clean conditions using formic acid. The coagulated latex can then be processed into

7776-400: The preponderance of wrinkled conformations over more linear ones. For the quantitative treatment see ideal chain , for more examples see entropic force . Cooling below the glass transition temperature permits local conformational changes but a reordering is practically impossible because of the larger energy barrier for the concerted movement of longer chains. "Frozen" rubber's elasticity

7872-456: The presence of copper(I) chloride , rearranges to the targeted 2-chlorobuta-1,3-diene: This process is energy-intensive and has high investment costs. Furthermore, the intermediate vinyl acetylene is unstable. This "acetylene process" has been replaced by a process which adds Cl 2 to 1,3-butadiene , giving 1,4-dichloro-2-butene . Isomerization of the latter gives 1,2-dichloro-3-butene, which undergoes dehydrochlorination :: Chloroprene

7968-422: The previously coagulated material. The rubber/acid mixture is what gives rubber plantations, markets, and factories a strong odor. Tree lace is the coagulum strip that the tapper peels off the previous cut before making a new cut. It usually has higher copper and manganese contents than cup lump. Both copper and manganese are pro-oxidants and can damage the physical properties of the dry rubber. Smallholders' lump

8064-444: The product's reputation, the trademark DuPrene was restricted to apply only to the material sold by DuPont. Since the company itself did not manufacture any DuPrene-containing end products, the trademark was dropped in 1937 and replaced with a generic name, neoprene, in an attempt "to signify that the material is an ingredient, not a finished consumer product". DuPont then worked extensively to generate demand for its product, implementing

8160-419: The related Scorzonera tau-saghyz , various Taraxacum species, including common dandelion ( Taraxacum officinale ) and Kazakh dandelion, and, perhaps most importantly for its hypoallergenic properties, guayule ( Parthenium argentatum ). The term gum rubber is sometimes applied to the tree-obtained version of natural rubber in order to distinguish it from the synthetic version. The first use of rubber

8256-513: The skin. An A2 designation by the ACGIH means that the substance is a suspected human carcinogen with support from human data that are accepted as adequate in quality but may not be enough to declare an A1 (known human carcinogen) designation. Additionally, the TLV basis for these designations are due to scientific studies that show an association between chloroprene exposure and lung cancer, upper respiratory tract (URT) and eye irritation. Chloroprene

8352-564: The synthetic rate decreases with complete removal. More than 28 million tons of rubber were produced in 2017, of which approximately 47% was natural. Since the bulk is synthetic, which is derived from petroleum, the price of natural rubber is determined, to a large extent, by the prevailing global price of crude oil. Asia was the main source of natural rubber, accounting for about 90% of output in 2021. The three largest producers, Thailand , Indonesia, and Malaysia, together account for around 72% of all natural rubber production. Natural rubber

8448-418: The synthetic rubber, polychloroprene. NIOSH developed a list of actions to address specific workplace hazards. These actions are represented in their diagram of the " Hierarchy of Controls " shown below with the most effective steps at the top and the least effective at the bottom. The high vaporization potential and flammability of chloroprene has significant implications for handling and storage operations in

8544-435: The terminal high-energy pyrophosphate. The reaction produces a cis polymer. The initiation step is catalyzed by prenyltransferase , which converts three monomers of isopentenyl pyrophosphate into farnesyl pyrophosphate . The farnesyl pyrophosphate can bind to rubber transferase to elongate a new rubber polymer. The required isopentenyl pyrophosphate is obtained from the mevalonate pathway, which derives from acetyl-CoA in

8640-453: The way of the growing crystallites . Crystallization has occurred, for example, when, after days, an inflated toy balloon is found withered at a relatively large remaining volume. Where it is touched, it shrinks because the temperature of the hand is enough to melt the crystals. Vulcanization of rubber creates di- and polysulfide bonds between chains, which limits the degrees of freedom and results in chains that tighten more quickly for

8736-410: The work was based upon that of Julius Arthur Nieuwland , with whom they collaborated. Chloroprene is produced in three steps from 1,3- butadiene : (i) chlorination , (ii) isomerization of part of the product stream, and (iii) dehydrochlorination of 3,4-dichlorobut-1-ene. Chlorine adds to 1,3-butadiene to afford a mixture of 3,4-dichlorobut-1-ene and 1,4-dichlorobut-2-ene. The 1,4-dichloro isomer

8832-442: The world. As the cost of natural rubber has risen significantly and rubber products are dense, the shipping methods offering the lowest cost per unit weight are preferred. Depending on destination, warehouse availability, and transportation conditions, some methods are preferred by certain buyers. In international trade, latex rubber is mostly shipped in 20-foot ocean containers. Inside the container, smaller containers are used to store

8928-670: Was by the indigenous cultures of Mesoamerica . The earliest archeological evidence of the use of natural latex from the Hevea tree comes from the Olmec culture, in which rubber was first used for making balls for the Mesoamerican ballgame . Rubber was later used by the Maya and Aztec cultures: in addition to making balls, Aztecs used rubber for other purposes, such as making containers and to make textiles waterproof by impregnating them with

9024-760: Was first called 'india rubber,' because it came from the Indies, and the earliest European use of it was to rub out or erase. It is now called India rubber because it rubs out or erases the Indians." In India , commercial cultivation was introduced by British planters, although the experimental efforts to grow rubber on a commercial scale were initiated as early as 1873 at the Calcutta Botanical Garden . The first commercial Hevea plantations were established at Thattekadu in Kerala in 1902. In later years

9120-490: Was identified by some health experts as an effective material to use for home made face masks. Some commercial face mask manufacturers that use neoprene have claimed 99.9% filtration for particles as small as 0.1 microns. The size of coronavirus is identified to be on average 0.125 microns. Neoprene is used for Halloween masks and masks used for face protection, to make waterproof automotive seat covers, in liquid and sheet-applied elastomeric roof membranes or flashings, and in

9216-724: Was later to become the biggest producer of rubber. In the early 1900s, the Congo Free State in Africa was also a significant source of natural rubber latex, mostly gathered by forced labor . King Leopold II's colonial state brutally enforced production quotas due to the high price of natural rubber at the time. Tactics to enforce the rubber quotas included removing the hands of victims to prove they had been killed. Soldiers often came back from raids with baskets full of chopped-off hands. Villages that resisted were razed to encourage better compliance locally. (See Atrocities in

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