Hevea brasiliensis rubber, natural

Before 1800 Cotton, flax, wool, and silk fibers bitumens caulking materials glass and hydraulic cements leather and cellulose sheet (paper) natural rubber Hevea brasiliensis), gutta percha, balata, and shellac 1839 Vulcanization of rubber (Charles Goodyear)... 

Natural rubber (Hevea brasiliensis) is as-poly-2-methyl-1,4-butadiene, and gutta-percha (Palaquium oblongi/olium) and balata (Minusops globosa) are polymers of isoprene (2-methyl-1,4-butadiene) with trans configurations. Neoprene is a polymer of 2-chloro-1,3-butadiene (chloroprene). 

Keywords Natural rubber, Hevea brasiliensis, cultivation, modification, primary processing, manufacturing techniques, pneumatic tyre, non-tyre products, vulcanization, green commodity... 

Chromenes, Benzofurans, Benzopyrans, and Precocenes Polyterpenes Biosynthesis Biological Activity Natural Rubber Hevea brasiliensis Guayule Gutta Percha Chicle... 

THERMAL ANALYSIS OF NATURAL RUBBER HEVEA BRASILIENSIS LATEX... 

A.K. Krishnakumar, C.Gupta, R.R.Sinha, M.RSethuraj, S.N.Potty, T. Happen, and K. Das, Ecological impact of rubber (Hevea brasiliensis) plantations in North East India 2. Soil properties and biomass recycling, Indian Journal of Natural Rubber Research, 4(2), 131-141,1991. 

B. Kositsup, P. Kasemsap, P. Thaler and T. Ameglio, Effect of temperature constraints on photosynthesis of rubber (Hevea brasiliensis), Proceedings IRRDB International Natural Rubber Conference, Siam Reap, Cambodia, 2007, p. 161-166. 

Natural rubber can be obtained from the sap of a number of plants and trees, the most common source is the Hevea brasiliensis tree. Although natural rubber was known in Central and South America before the arrival of Christopher Columbus in 1492, the first use as an adhesive was established in a patent dated in 1891. As rubber became an important part of the industrial revolution, the rubber adhesives market grew in importance. To comply with the increasing demand on natural rubber materials, plantations of Hevea brasiliensis trees were established in southeast Asia in the early 20th Century, mainly to supply the demand from the automobile industry. 

Natural rubber is obtained from the bark of the rubber tree, Hevea brasiliensis, grown on enormous plantations in Southeast Asia. 

Rubber—an unusual name for an unusual substance—is a naturally occurring aikene polymer produced by more than 400 different plants. The major source is the so-called rubber tree, Hevea brasiliensis, from which the crude material is harvested as it drips from a slice made through the bark. The name rubber was coined by Joseph Priestley, the discoverer of oxygen and early researcher of rubber chemistry, for the simple reason that one of rubber s early uses was to tub out pencil marks on paper. 

In 1994, the worldwide consumption of rubber was approximately 14.5 million tons a year, of which about 40% consisted of natural rubber. Natural rubber is produced as latex by tropical rubber trees (Hevea brasiliensis). It is processed locally and therefore the quality of natural rubber fluctuates remarkably [ 140]. Due to increasing demand for rubbers, combined with a decreasing production capacity in Asia and a vast increase in labor costs, the price of natural rubber is still rising sharply. In 1990-1994, the average price of natural rubber was about 0.38 /lb, while in 1996 it was already over 0.80 /lb. The remaining 60% of the articles were manufactured from synthetic petroleum-based rubbers such as isoprene rubber, styrene-butadiene rubber, chloroprene rubber and polyurethanes. The quality of synthetic rubbers is constant, and their price varies between 2 and 5 US per kilogram [137-140]. 

Rubber obtained from botanical sources. The bulk of natural rubber is obtained from the Hevea Brasiliensis free with small amounts from other vines, shrubs and plants mainly the Guayule shrub and the Kok-Saghyz plant. See Isoprene. 

Diene polymers refer to polymers synthesized from monomers that contain two carbon-carbon double bonds (i.e., diene monomers). Butadiene and isoprene are typical diene monomers (see Scheme 19.1). Butadiene monomers can link to each other in three ways to produce ds-1,4-polybutadiene, trans-l,4-polybutadi-ene and 1,2-polybutadiene, while isoprene monomers can link to each other in four ways. These dienes are the fundamental monomers which are used to synthesize most synthetic rubbers. Typical diene polymers include polyisoprene, polybutadiene and polychloroprene. Diene-based polymers usually refer to diene polymers as well as to those copolymers of which at least one monomer is a diene. They include various copolymers of diene monomers with other monomers, such as poly(butadiene-styrene) and nitrile butadiene rubbers. Except for natural polyisoprene, which is derived from the sap of the rubber tree, Hevea brasiliensis, all other diene-based polymers are prepared synthetically by polymerization methods. 

Renewable raw materials are made or derived from short-term renewable sources (one to a few years or a few tens of years) such as plants, trees, wood wastes and other agricultural products. Not all these materials are necessarily biodegradable. Natural rubber, for example, comes from the latex of a tree (Hevea brasiliensis) and is not biodegradable. Renewable materials are often considered as opposites to fossil sources such as petroleum that are not renewable on a human timescale. On the other hand, some synthesized plastics such as certain polyesters are biodegradable. 

Synonyms Natural latex—milky fluid that consists of extremely small particles of rubber obtained from plants, principally from the Hevea brasiliensis (rubber) tree, dispersed in an aqueous medium. It contains a variety of naturally occurring substances in a colloidal suspension, including about 1% proteins (e.g., a-globulins, hevein), which are the allergenic fraction. ... 

Natural rubber can be found as a colloidal emulsion in a white, milky fluid called latex and is widely distributed in the plant kingdom. The Indians called it wood tears. It was not until 1770 that Joseph Priestly suggested the word rubber for the substance, since by rubbing on paper it could be used to erase pencil marks, instead of the previously used bread crumbs. At one time 98% of the world s natural rubber came from a tree, Hevea brasiliensis, native to the Amazon Basin of Brazil which grows to the height of 120 ft. Today most natural rubber is produced on plantations in Malaysia, Indonesia, Singapore, Thailand, and Sri Lanka. Other rubber-bearing plants... 

Until the 1930s natural rubber from Hevea brasiliensis was the only available elastomer. The United States had to, and still does, import every pound. Although research on synthetic substitutes began before 1940 in this country. World War II influenced speedy development of substitutes when our supply of natural rubber from the Far East was cut off. Gasoline had to be rationed not because of its shortage, but because of the automobile tire shortage. 

Natural rubber - Rubber formed in a living plant or tree, usually referring to Hevea Brasiliensis. ASTM designation NR. 

Natural Rubbers (NR). The chemical name for NR is polyisoprene, which is a homopolymer of isoprene. It has the cis-1,4 configuration. In addition, the polymer contains small amounts of non-rubber substances, notably fatty acids, proteins, and resinous materials that function as mild accelerators and activators for vulcanization. Raw materials for the production of NR must be derived from trees of the Hevea Brasiliensis species. NR is available in a variety of types and grades, including smoked sheets, air-dried sheets, and pale crepes. 

Natural rubber, chemically speaking poly(W.v-1,4-isoprene), is a natural polymer derived from Hevea brasiliensis and various other tropical plants like Castilloa elastica [147]. This natural polymer is mainly produced in Asia and the tropics in high, industrially relevant, amounts (e.g., 9.7 Mio mto in 2007). Apart from its usual use as an elastomeric material, some research was devoted onto the metathesis degradation (depolymerization) of natural rubber with ethylene in a CM fashion. It was believed that metathesis of natural rubber is impossible, until a pioneering... 

Natural rubber is isolated from a white fluid, called latex, that exudes from cuts in the bark of Hevea brasiliensis, the South American rubber tree. Many other plants secrete this polymer, as well. The name rubber was first used by Joseph Priestly, who used the crude material to rub out errors in his pencil writing. Natural rubber is soft and sticky. An enterprising Scotsman named Charles Macintosh found that rubber makes a good waterproof coating for raincoats. Natural rubber is not strong or elastic, however, so its uses were limited to waterproofing cloth and other strong materials. 

Natural rubber (latex solids) Hevea brasiliensis... 

Natural rubber is extracted from the hevea brasiliensis tree which is grown in tropical regions. When its bark is slit with a cutter, a liquid, named latex, is obtained. Latex is an emulsion of rubber in water. When acid is added to this emulsion, natural rubber is precipitated. This precipitate is the polymer of a hydrocarbon with the molecular formula CgHg... 

Sando, T., Takaoka, C., Mukai, Y., Yamashita, A., Hattori, M., Ogasawara, N., Fukusaki, E. and Kobayashi, A. (2008) Cloning and characterization of meval-onate pathway genes in a natural rubber producing plant, Hevea brasiliensis. Biosci. Biotechnol. Biochem., 71, 2049-60. 

Natural rubber, a terpene composed of repeating isoprene units, is isolated from latex, a sticky white fluid that oozes from Hevea brasiliensis, the South American rubber tree, when its bark is cut. The word rubber was first suggested by English chemist Joseph Priestly in 1770, when he used latex to rub out pencil markings. Rubber is a polymer containing 1,5-diene units in which all the double bonds have the Z configuration. In Chapter 30, we learn about the synthesis and properties of polymers like rubber. 

It is obtained from latex extracted from the Hevea brasiliensis tree. There exists another structural isomer called gutta-percha formed from po y trans-1,4-isoprene), whose elastic properties differ from those of natural rubber. 

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