Hevea brasiliensis, rubber from

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. ... 

Alstonia boonei (Apocynaceae) [root], Ficus variegata (Moraceae), Hevea brasiliensis (rubber) (Euphorbiaceae) [latex], Erythroxylum coca (Erythroxylaceae), Balanophora elongata (Balanophoraceae) Semi-synthetic from ct-Amyrin... 

Rubber. Rubber is an organic substance, obtained mainly from tlie sap of the rubber tree, Hevea brasiliensis. Rubber consists of very long molecules, which are polymers of isoprene, CgHg. The structure ol isoprt ne is... 

X. Gidrol, H. Chrestin, H. L. Tan, and A. Kush, Hevein, a lectin-like protein from Hevea brasiliensis (rubber tree) is involved in the coagulation of latex, J. Biol. Chem., 269 (1994) 9278-9283. 

Rubber can be obtained from a number of trees, but commercial production is done with tropical plant Hevea brasiliensis. Rubber is a polymer of a single monomer isoprene (2-methyl butadiene). Isoprene itself can chemically (i.e., artificially) be polymerized by various means to produce polyisoprene, but this is not the way the natural rubber is produced in rubber trees. The biological process to produce rubber (i.e., biological polymerization) is shown in Fig. 5.5. This process is a kind of condensation with removal of a pyrophosphate group... 

Natural rubber is obtained from the latex of the Hevea brasiliensis (rubber tree), which is indigenous to the Amazon basin of Brazil. In 1876, Sir Henry Wickham smuggled out about 70,000 rubber tree seeds and brought them to London. These seeds were used to start rubber tree plantations in Southeast Asia, where 85% of the world s supply of natural rubber is produced today. 

Natural rubber is derived directly from the latex of the Hevea brasiliensis (rubber tree), which is grown in regions close to the equator. Figure 3.1. 

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. 

Originally from China, Rhus vernicefera has been under cultivation in Japan since the sixth century AD. The latex is collected in the same way as the rubber plant Hevea brasiliensis. The product is known as urushiol, which consists mostly of dihydric phenols of structures (Fig. 6) and is used as lacquers. 

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. 

Rubber is obtained from the juice of various tropical trees, mainly the tree Hevea brasiliensis. The juice is a latex consisting of a dispersion of polymer phase at a concentration of about 35% by mass, together with traces of proteins, sterols, fats, and salts. The rubber is obtained either by coagulation of the latex with acid, either ethanoic or methanoic, or by evaporation in air or over a flame. The material that results from this process is a crumbly, cheeselike substance, sometimes called raw rubber or caoutchouc. In order to... 

Hasslacher, M., Schall, M., Hayn, M. et al. (1997) High-level intracellular expression of hydroxynitrile lyase from the tropical rubber tree Hevea brasiliensis in microbial hosts. Protein Expression and Purification, 11, 61-71. 

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. 

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. 

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