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89-483: Vulcanization (British English: vulcanisation ) is a range of processes for hardening rubbers . The term originally referred exclusively to the treatment of natural rubber with sulfur , which remains the most common practice. It has also grown to include the hardening of other (synthetic) rubbers via various means. Examples include silicone rubber via room temperature vulcanizing and chloroprene rubber (neoprene) using metal oxides. Vulcanization can be defined as

178-490: 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

267-423: 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

356-785: 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 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

445-434: A cure site of another polymer chain. These bridges contain between one and several atoms. The number of sulfur atoms in the crosslink strongly influences the physical properties of the final rubber article. Short crosslinks give the rubber better heat resistance. Crosslinks with higher number of sulfur atoms give the rubber good dynamic properties but less heat resistance. Dynamic properties are important for flexing movements of

534-598: 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

623-447: 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

712-510: 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

801-752: 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

890-515: 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 is the Amazonian rubber tree ( Hevea brasiliensis ), a member of the spurge family , Euphorbiaceae . Once native to Brazil,

979-580: 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

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1068-438: 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

1157-432: 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

1246-435: 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

1335-451: 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

1424-453: 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

1513-401: 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

1602-442: 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

1691-453: 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

1780-418: 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

1869-417: 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;

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1958-417: 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

2047-532: 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 is used extensively in many applications and products, either alone or in combination with other materials. In most of its useful forms, it has

2136-415: 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

2225-491: 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

2314-495: Is generally irreversible. The word was suggested by William Brockedon (a friend of Thomas Hancock who attained the British patent for the process) coming from the god Vulcan who was associated with heat and sulfur in volcanoes . In ancient Mesoamerican cultures, rubber was used to make balls, sandal soles, elastic bands, and waterproof containers. It was cured using sulfur-rich plant juices, an early form of vulcanization. In

2403-438: 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

2492-457: 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 a lecture by Fr Julius Arthur Nieuwland , a professor of chemistry at the University of Notre Dame . Nieuwland's research

2581-556: 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

2670-439: 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

2759-892: 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

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2848-435: 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

2937-582: 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

3026-449: 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

3115-529: 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

3204-553: 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 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

3293-402: 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

3382-524: 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

3471-472: 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

3560-503: 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

3649-448: 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

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3738-496: 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,

3827-697: 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

3916-409: The curing of elastomers , with the terms 'vulcanization' and 'curing' sometimes used interchangeably in this context. It works by forming cross-links between sections of the polymer chain which results in increased rigidity and durability, as well as other changes in the mechanical and electrical properties of the material. Vulcanization, in common with the curing of other thermosetting polymers ,

4005-557: 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

4094-584: The 1830s, Charles Goodyear worked to devise a process for strengthening rubber tires. Tires of the time would become soft and sticky with heat, accumulating road debris that punctured them. Goodyear tried heating rubber in order to mix other chemicals with it. This seemed to harden and improve the rubber, though this was due to the heating itself and not the chemicals used. Not realizing this, he repeatedly ran into setbacks when his announced hardening formulas did not work consistently. One day in 1839, when trying to mix rubber with sulfur , Goodyear accidentally dropped

4183-452: 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 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

4272-649: 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

4361-538: The European rubber industry had a research project titled SafeRubber to develop a safer alternative to the use of ETU. Room-temperature vulcanizing (RTV) silicone is constructed of reactive oil-based polymers combined with strengthening mineral fillers. There are two types of room-temperature vulcanizing silicone: Rubber Rubber , also called India rubber , latex , Amazonian rubber , caucho , or caoutchouc , as initially produced, consists of polymers of

4450-409: 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

4539-418: The behaviour of most modern polymers), vulcanization, in common with the curing of other thermosetting polymers , is generally irreversible. Five types of curing systems are in common use: The most common vulcanizing methods depend on sulfur. Sulfur, by itself, is a slow vulcanizing agent and does not vulcanize synthetic polyolefins . Accelerated vulcanization is carried out using various compounds that modify

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4628-413: 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

4717-407: 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

4806-654: 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

4895-421: 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 ) was later to become the biggest producer of rubber. In

4984-636: 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

5073-477: 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

5162-544: 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

5251-459: 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

5340-431: 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

5429-577: The kinetics of crosslinking; this mixture is often referred to as a cure package. The main polymers subjected to sulfur vulcanization are polyisoprene ( natural rubber ) and styrene-butadiene rubber (SBR), which are used for most street-vehicle tires. The cure package is adjusted specifically for the substrate and the application. The reactive sites—cure sites—are allylic hydrogen atoms. These C-H bonds are adjacent to carbon-carbon double bonds (>C=C<). During vulcanization, some of these C-H bonds are replaced by chains of sulfur atoms that link with

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5518-402: 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 –

5607-434: 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

5696-416: 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

5785-443: 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

5874-399: 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

5963-411: 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

6052-753: The mixture in a hot frying pan. To his astonishment, instead of melting further or vaporizing , the rubber remained firm and, as he increased the heat, the rubber became harder. Goodyear worked out a consistent system for this hardening, and by 1844 patented the process and was producing the rubber on an industrial scale. There are many uses for vulcanized materials, some examples of which are rubber hoses, shoe soles, toys, erasers, hockey pucks, shock absorbers, conveyor belts, vibration mounts/dampers, insulation materials, tires, and bowling balls. Most rubber products are vulcanized as this greatly improves their lifespan, function, and strength. In contrast with thermoplastic processes (the melt-freeze process that characterize

6141-455: 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 is harvested mainly in the form of the latex from the Pará rubber tree ( Hevea brasiliensis ) or others. The latex

6230-561: 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

6319-453: The premature cross-linking of rubbers due to the influence of heat), the choice of accelerator is governed by different rules to other diene rubbers. Most conventionally used accelerators are problematic when CR rubbers are cured and the most important accelerant has been found to be ethylene thiourea (ETU), which, although being an excellent and proven accelerator for polychloroprene, has been classified as reprotoxic . From 2010 to 2013,

6408-589: 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

6497-400: 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

6586-460: The previous 5–10 years, and other areas were affected by climate-fueled natural disasters. In this environment, producers did increase their prices in keeping with supply and demand dynamics, putting upward price pressure on the whole downstream supply chain. Neoprene Neoprene is produced by free-radical polymerization of chloroprene . In commercial production, this polymer is prepared by free radical emulsion polymerization . Polymerization

6675-422: 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

6764-446: 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

6853-537: The rubber article, e.g., the movement of a side-wall of a running tire. Without good flexing properties these movements rapidly form cracks, and ultimately will make the rubber article fail. The vulcanization of neoprene or polychloroprene rubber (CR rubber) is carried out using metal oxides (specifically MgO and ZnO , sometimes Pb 3 O 4 ) rather than sulfur compounds which are presently used with many natural and synthetic rubbers . In addition, because of various processing factors (principally scorch, this being

6942-420: The rubber fig ( Ficus elastica ), Panama rubber tree ( Castilla elastica ), various spurges ( Euphorbia spp.), lettuce ( Lactuca species), 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

7031-566: 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 the Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) in Germany developed

7120-454: 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 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

7209-564: 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

7298-435: 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

7387-453: 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

7476-442: 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

7565-468: 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 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

7654-736: 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

7743-611: 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

7832-493: 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

7921-518: 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 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

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