98-546: Ngoyo was a kingdom of the Woyo ethnic group, located in the south of Cabinda and on the Atlantic coast of Central Africa , just north of the Congo River . In the 13th century it formed part of a confederation led by Vungu . Ngoyo tradition held that the kingdom's ancestors were among the earliest settlers in the area, leading their chiefs to title themselves the nfumu nsi ("lords of
196-532: A naval base in the western part of Cabinda, making it the only Brazilian colony outside of South America. Portugal first claimed sovereignty over Cabinda in the February 1885 Treaty of Simulambuco , which gave Cabinda the status of a protectorate of the Portuguese Crown under the request of "the princes and governors of Cabinda". This is often the basis upon which the legal and historical arguments in defense of
294-676: A charter member of the Organization of Emerging African States (OEAS). An ad-hoc United Nations commission for human rights in Cabinda reported in 2003 that many atrocities had been perpetrated by the MPLA. In 2004, according to Peter Takirambudde , executive director of the Human Rights Watch mission for Africa, the Angolan army continued to commit crimes against civilians in Cabinda. Although
392-785: 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
490-447: 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
588-510: 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
686-752: 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
784-432: 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
882-435: 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
980-509: A population of 716,076 at the 2014 census; the latest official estimate (as at mid-2019) is 824,143. According to 1988 United States government statistics , the total population of the province was 147,200, with a near even split between rural and urban populations. At one point an estimated one third of Cabindans were refugees living in the Democratic Republic of the Congo ; however, after
1078-451: 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
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#17328987184931176-453: 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
1274-578: A whole, largely because of corruption. The private sector, particularly the oil industry , has both affected and been affected by the secessionist conflict. During the early days of Cabinda's struggle, the oil companies were perceived as sympathetic to, if not supportive of, Cabinda's self-determination cause. The strategy used by the separatists to gain international attention, was most evident in 1999 and 2000. During 1999, FLEC-R kidnapped four foreign workers (two Portuguese and two French citizens), but released them after several months, having failed to attract
1372-401: 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
1470-442: 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
1568-418: 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
1666-474: Is an exclave and province of Angola , a status that has been disputed by several political organizations in the territory. The capital city is also called Cabinda , known locally as Tchiowa , Tsiowa or Kiowa . The province is divided into four municipalities— Belize , Buco-Zau , Cabinda and Cacongo . Modern Cabinda is the result of a fusion of three kingdoms: N'Goyo , Loango and Kakongo . It has an area of 7,290 km (2,810 sq mi) and
1764-566: Is associated with Sonangol , Agip Angola Lda (41%), Chevron (39.2%), TotalEnergies (10%) and Eni (9.8%). In 1885, the Treaty of Simulambuco established Cabinda as a protectorate of the Portuguese Empire , and Cabindan independence movements consider the occupation of the territory by Angola illegal. While the Angolan Civil War largely ended in 2002, an armed struggle persists in
1862-415: 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
1960-464: 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,
2058-491: 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
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#17328987184932156-465: Is estimated that oil exports from the province are worth the equivalent of US$ 100,000 per annum for every Cabindan. Yet Cabinda remains one of the poorest provinces in Angola. An agreement in 1996 between the national and provincial governments stipulated that 10% of Cabinda's taxes on oil revenues would be given back to the province, but Cabindans often feel that these revenues do not benefit the population as
2254-438: 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
2352-556: 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
2450-892: 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
2548-568: Is obliged to maintain the integrity of the territories placed under its protection". The Front for the Liberation of the Enclave of Cabinda (FLEC-R) argues that the above-mentioned treaty was signed between the emissaries of the Portuguese Crown and the princes and notables of Cabinda, then called Portuguese Congo, giving rise to not one, but three protectorates: Cacongo, Loango, and Ngoio. Through
2646-582: 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
2744-449: 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
2842-529: 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
2940-422: 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 a large stretch ratio and high resilience and also
3038-553: 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
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3136-402: 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
3234-472: 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
3332-496: 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,
3430-649: 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
3528-560: The Treaty of Simulambuco , three kingdoms existed in what is now referred to as Cabinda: Cacongo, Ngoyo, and Loango. The Cabindans belong to the Bakongo ethnic group whose language is Kikongo . The Bakongo also comprise the majority of the population in Uíge and Zaire provinces of Angola . However, despite this shared ancestry, the Cabindans developed a very different culture and distinct variants of
3626-557: 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
3724-400: The self-determination of modern-day Cabinda are constructed. Article 1, for example, states, "the princes and chiefs and their successors declare, voluntarily, their recognition of Portuguese sovereignty, placing under the protectorate of this nation all the territories by them governed" [ sic ]. Article 2, which is often used in separatist arguments, goes even further: "Portugal
3822-520: The 2007 peace agreement, refugees started returning to their homes. Cabinda is separated from the rest of Angola by a narrow strip of territory belonging to the Democratic Republic of the Congo (formerly known, up until 1960, as the Belgian Congo ), which bounds the province on the south and the east. Cabinda is bounded on the north by the Republic of the Congo (formerly known as French Congo ), and on
3920-585: The 2014 Census and according to the latest official estimates: The city of Cabinda contains 87% of the provincial population. The other three municipalities lie to the north of the city. The province of Cabinda contains the following communes ( Portuguese : comunas ); sorted by their respective municipalities: Two giant oil fields , the Malonga North and Malonga West were discovered in 1967 and 1970, respectively, both pre-salt or pre- Aptian producers. Located in water depths of 50 to 75 m, oil
4018-452: 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
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4116-519: The Angolan government says FLEC is no longer operative, this is disputed by the Republic of Cabinda and its Premier, Joel Batila. Earlier increases in the price of oil have made Cabinda's untapped onshore oil reserves a valuable commodity. In July 2006, after ceasefire negotiations in the Republic of Congo, António Bento Bembe – as a president of Cabindan Forum for Dialogue and Peace, and vice-president and executive secretary of FLEC – announced that
4214-561: The Angolans, and that the only acceptable solution is total independence. On 8 January 2010, the bus carrying the Togo national football team traveling through Cabinda en route to the 2010 Africa Cup of Nations tournament was attacked by gunmen, even though it had an escort of Angolan forces. The ensuing gunfight resulted in the deaths of the assistant coach, team spokesman and bus driver, and caused injuries to several others as well. An offshoot of
4312-696: The Cabindan separatist forces were ready to declare a ceasefire. Bembe is the leader of the " Cabindan Forum for Dialogue ", an organization which represents most Cabindan groups . The peace was recognized by the United States, France, Portugal, Russia , Gabon, Democratic Republic of the Congo , Republic of the Congo , Japan , South Korea , the European Union and the African Union. From Paris, FLEC-FAC contended Bembe has no authority or mandate to negotiate with
4410-649: 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
4508-549: The FLEC claimed responsibility. Rodrigues Mingas , secretary general of the Front for the Liberation of the Enclave of Cabinda-Military Position (Flec-PM), said his fighters had meant to attack security guards as the convoy passed through Cabinda. "This attack was not aimed at the Togolese players but at the Angolan forces at the head of the convoy", Mingas told France 24 television. "So it
4606-567: The Kikongo language. In the early 1960s, several movements advocating a separate status for Cabinda came into being. The Movement for the Liberation of the Enclave of Cabinda (MLEC) was formed in 1960 under the leadership of Luis Ranque Franque . Resulting from the merger of various émigré associations in Brazzaville , the MLEC rapidly became the most prominent of the separatist movements. A further group
4704-620: The Kingdoms of Ngoyo , Loango , and Kakongo in present-day Cabinda. Over the years, the Portuguese, Dutch , and English established trading posts , logging camps, and small palm oil processing factories in Cabinda. Trade continued and the European presence grew, resulting in conflicts between the rival colonial powers. Between 1827 and 1830, the Imperial Brazilian Navy maintained
4802-489: The Portuguese constitution of 1933 until 15 January 1975 under the Alvor Agreement. The Portuguese constitution of 1933 distinguished between the colony of Angola and the protectorate of Cabinda, but in 1956, the administration of Cabinda was transferred to the governor-general of Angola. The legal distinction of Cabinda's status from that of Angola was also expressed in the Portuguese constitution of 1971. Yet, when Angola
4900-624: The Treaty of Simulambuco in 1885 between the kings of Portugal and the princes of Cabinda, a Portuguese protectorate was decreed, reserving rights to the local princes and independent of Angola. Cabinda once had the Congo River as the only natural boundary with Angola, but in 1885, the Berlin Conference extended the territory of the Congo Free State along the Congo River to the river's mouth at
4998-409: 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
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#17328987184935096-557: The attention of the international community. FLEC-FAC also increased its activities during 2000 with the more widely publicized kidnapping of three Portuguese workers employed by a construction company, while FLEC-R kidnapped another five Portuguese civilians. These hostages were not freed until June 2001, following diplomatic intervention by the governments of Gabon and the Republic of the Congo . The province of Cabinda consists of four municipalities ( Portuguese : municípios ); listed below with their areas (in km ) and populations at
5194-502: The capital of the territory, was a Portuguese administrative and services center with a port and airfield. The beaches of Cabinda were popular with Portuguese Angolans. A 1974 military coup in Lisbon abolished the authoritarian regime established by António de Oliveira Salazar that had prevailed in Portugal for decades. The new government decided immediately to grant all Portuguese colonies
5292-407: 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
5390-596: 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
5488-482: The earth"). The capital was Mbanza Ngoyo . In the 1630s Ngoyo was invaded by the forces of Soyo , and the son of the ruler of Soyo was installed as ruler of Ngoyo. It is not clear who the following rulers were for the next few decades. In the 1680s Ngoyo had various relations with Soyo. It also had several English merchants present. When Antonio II Baretto da Silva invaded, the English forces tried to stop him and protect
5586-515: The exclave of Cabinda. Some of the factions have proclaimed an independent Republic of Cabinda , with offices in Paris . Portuguese explorers, missionaries , and traders arrived at the mouth of the Congo River in the mid-15th century, making contact with the Manikongo , the powerful King of the Bakongo tribe . The Manikongo controlled much of the region through affiliation with smaller kingdoms, such as
5684-421: 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
5782-636: 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
5880-477: 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
5978-544: 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
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#17328987184936076-459: 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
6174-551: The independence for which nationalist guerilla movements had been striving. In Angola, the decolonization process took the form of a violent conflict between the different guerilla movements and their allies. In 1975, the Treaty of Alvor between Portugal and National Liberation Front of Angola (FNLA), People's Movement for the Liberation of Angola ( MPLA ) and National Union for the Total Independence of Angola ( UNITA ) reconfirmed Cabinda's status as part of Angola. The treaty
6272-405: The interests of Ngoyo, but they were unsuccessful and Baretto da Silva imposed for peace terms. By 1700, Cabinda had become the leading slave port north of Luanda , and Ngoyo's economy rested heavily on the sale of slaves. In 1783, Ngoyo joined forces with the neighboring state of Kakongo to destroy a Portuguese fort. However, the kingdom was soon undone by the growing financial burden that
6370-431: 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
6468-542: The kingship entailed. With fewer and fewer possible claimants seeking the office, the kingdom effectively disintegrated in the 1830s after the nobles failed to elect a new king. In 1885, the Ngoyo signed the Treaty of Simulambuco with Portugal , and became a protectorate of that nation. This African history –related article is a stub . You can help Misplaced Pages by expanding it . Cabinda (province) Cabinda (formerly called Portuguese Congo , Kongo : Kabinda )
6566-402: 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 –
6664-434: 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
6762-416: 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
6860-469: 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 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
6958-443: 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
7056-490: The majority of Organization of African Unity (OAU) members, concerned that this could encourage separatism elsewhere on the continent , committed to the sanctity of state borders and firmly rejected recognition of the FLEC's government in exile. In January 1975, Angola's MPLA, FNLA and UNITA liberation movements signed the Alvor Agreement with Portugal, to establish the modalities of the transition to independence. FLEC
7154-399: 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
7252-508: The official name was Provincial Commissioner 15th century 16th century 15th century 16th century 17th century 18th century 19th century 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
7350-561: 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
7448-589: 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
7546-400: 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
7644-422: 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
7742-590: The province's oil and construction businesses. The National Union for the Liberation of Cabinda ( Portuguese : União Nacional de Libertação de Cabinda ; UNLC), a militant separatist group, emerged in the 1990s under the leadership of Lumingu Luis Gimby. In April 1997, Cabinda joined the Unrepresented Nations and Peoples Organization , a democratic and international organization whose members are indigenous peoples , occupied nations , minorities and independent states or territories. In 2010, Cabinda became
7840-420: 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
7938-566: 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
8036-469: The sea. During this time rubber was harvested and traded in Cabinda. Atrocities such as the cutting of hands were also committed there, although comprehensive reports on these atrocities were more scant and less publicly known compared to the neighbouring Congo Free State. By the mid-1920s, the borders of Angola had been finally established in negotiations with the neighboring colonial powers. From there on Angola and Cabinda were treated distinctively under
8134-454: 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
8232-564: 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
8330-435: 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
8428-453: 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
8526-620: The west by the Atlantic Ocean . Adjacent to the coast are some of the largest offshore oil fields in the world. Petroleum exploration began in 1954 with the Cabinda Gulf Oil Company, when the territory was under Portuguese rule . Cabinda also produces hardwoods , coffee , cacao , rubber , and palm oil products; however, petroleum production accounts for most of Cabinda's domestic product. Cabinda produces 700,000 barrels (110,000 m ) of crude oil per day. Cabinda Oil
8624-442: 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
8722-468: 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
8820-440: Was declared an " overseas province " (Província Ultramarina) within the empire of Portugal in 1951, Cabinda was treated as an ordinary district of Angola. In 1972, the name of Angola was changed to "State of Angola". Under Portuguese rule, Cabinda was an important agricultural and forestry center, and in 1967, it discovered huge offshore oil fields. Oil, timber, and cocoa had been its main exports until then. The town of Cabinda,
8918-656: Was discovered in Barremian deposits in 1971, then the Cenomanian section in 1979. Four offshore oil fields, the Wamba , Takula , Numbi and Vuko , are located in the greater Takula area, producing from the Upper Cretaceous , Cenomanian Vermelha sandstone deposited in the coastal environment. Cretaceous and Paleocene vertebrates, including fossil turtles as Cabindachelys have been collected from Lândana. Up to 1991,
9016-621: Was elected president. Following the declaration of Angolan independence in November 1975, Cabinda was invaded by forces of the Popular Movement for the Liberation of Angola (MPLA), with the support of Cuban troops. The MPLA overthrew the provisional FLEC government and incorporated Cabinda into Angola. For much of the 1970s and 1980s, FLEC operated a low intensity guerrilla war , attacking Angolan government troops and economic targets, or creating havoc by kidnapping foreign employees working in
9114-736: 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
9212-518: 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
9310-454: Was not invited. On 1 August 1975, at an OAU summit in Kampala which was discussing Angola in the midst of its turbulent decolonization process, Ranque Franque proclaimed the independence of the "Republic of Cabinda". Zairian President Mobutu Sese Seko called for a referendum on the future of Cabinda. FLEC formed a provisional government , led by Henriques Tiago . Luiz Branque Franque
9408-732: Was pure chance that the gunfire hit the players. We don't have anything to do with the Togolese and we present our condolences to the African families and the Togo government. We are fighting for the total liberation of Cabinda." Consisting largely of tropical forest , Cabinda produces hardwoods , coffee, cocoa, crude rubber, and palm oil. The product for which it is best known, however, is its oil . Conservative estimates say that Cabinda accounts for close to 60% of Angola's oil production, estimated at approximately 900,000 barrels per day (140,000 m /d), and it
9506-733: Was rejected by the Front for the Liberation of the Enclave of Cabinda and other local political organizations which advocated for separate independence. Since then, Cabinda has been, on the one hand, a normal Angolan province, but on the other hand, there has been persistent political protest against this status; the "Kabinda Free State" says the exclave was a Portuguese protectorate until Angola invaded in 1974. They also say they control 85% of Kabinda territory and invite proposals for joint ventures . A number of guerrilla actions have also occurred in Cabinda. The arguments for self-determination are based on Cabindans' cultural and ethnic background. Prior to
9604-693: Was the Alliama (Alliance of the Mayombe), representing the Mayombe , a small minority of the population. In an important development, these movements united in August 1963 to form a united front. They called themselves the FLEC, and the leadership role was taken by the MLEC's Ranque Franque. In marked contrast with the FNLA, the FLEC's efforts to mobilize international support for its government in exile met with little success. In fact,
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