Acrylonitrile-butadiene rubber Buna

Acrylonitrile-butadiene rubber (also called nitrile or nitrile butadiene rubber) was commercially available in 1936 under the name Buna-N. It was obtained by emulsion polymerization of acrylonitrile and butadiene. During World War II, NBR was used to replace natural rubber. After World War II, NBR was still used due to its excellent properties, such as high oil and plasticizer resistance, excellent heat resistance, good adhesion to metallic substrates, and good compatibility with several compounding ingredients. 

By 1929 the German firm I. G. Earben developed a series of synthetic rubbers similar to those produced in the USSR. They were called Buna rubbers ( Bu for butadiene, one of the copolymers, and na for sodium, the polymerization catalyst). They included the oil-resistant Buna S (S for styrene) and Buna N (N for nitrate). Buna S, styrene butadiene rubber, is currently called SBR, and it is produced at about twice the volume of natural rubber, making it the most common synthetic rubber. Buna N, acrylonitrile-butadiene rubber, is now called NBR. During World War II the United States produced these rubbers for the American war effort. 

The Swiss company, WW Fischer, offers PTFE (Teflon PTFE or Hostaflon), PBT (Celanex, Crastin, Ultradur or Valox) or PEEK (Victrex) insulator material options in its 405 series of cylindrical connectors according to the requirements of working temperature and other criteria. PEEK is an expensive polymer which tends to be employed when other materials fail to meet the specification requirements of the application. Other Fischer connector types use polyamide-imide (Torlon) or POM (Celcon, Delrin or Hostaform). Elastomeric seals used by Fischer in conjunction with their connectors are made from acrylonitrile-butadiene rubber (NBR N BUNA) or to MIL-P-25732, fluoroelastomer (FPM VITON), polychloroprene elastomer (CR Neoprene), ethylene-propylene diene elastomer (EPDM) and styrene-ethylene-butadiene-styrene thermoplastic elastomer (TPE-S or TPE-O) where each compound is followed by its trade name. Fischer s Swiss competitor, Lemo, manufactures a similar range of connectors including the Redel types which have a plastic body. 

The acrylonitrile-butadiene rubbers (NBR) may be most concisely described as the speciality rubbers with the conventional technology. First prepared in 1930, pilot plant production of the rubber commenced in 1934 with full scale production starting in Germany in 1937 under the name Buna N. The rubber thus preceded SBR as a commercial material. In order to circumvent German government restrictions on the export of Buna N shortly before World War II the rubber was shipped to the United States as Perbunan (a corruption of per-Buna N) and production of this material in the USA soon followed (to be known during the war as GR-A (Government Rubber-Acrylonitrile). 

Butadiene and isoprene have two double bonds, and they polymerize to polymers with one double bond per monomeric unit. Hence, these polymers have a high degree of unsaturation. Natural rubber is a linear cis-polyisoprene from 1,4-addition. The corresponding trans structure is that of gutta-percha. Synthetic polybutadienes and polyisoprenes and their copolymers usually contain numerous short-chain side branches, resulting from 1,2-additions during the polymerization. Polymers and copolymers of butadiene and isoprene as well as copolymers of butadiene with styrene (GR-S or Buna-S) and copolymers of butadiene with acrylonitrile (GR-N, Buna-N or Perbunan) have been found to cross-link under irradiation. 

Discovered in 1893 by the Frenchman Charles Moreu, acrylonitrile dl° - (L806t6), mp = -83.5°C, bp,ol3 — TJ3°Q remained a laboratory curiosity until the end of the First World War. Its industrial importance emerged around 1930. when it was osed in Germany and the United States to manufacture nitrile rubber. Buna N, a copolymer of butadiene and acrylonitrile, displaying high resistance to hydrocarbons. Since then, its applications have expanded considerably, including textile fibers, synthetic resins, elastomers, and intermediates of organic syntheses. 

In the late 1930 s, German chemists found that acrylonitrile-butadiene copolymers have unusual resistance to hydrocarbons. This discovery led to the development of nitrile rubbers, of which Buna N was the first, and created a demand for commercial quantities of acrylonitrile. Of the many possible synthetic methods, only two have been important commercially catalytic dehydration of ethylene cyanohydrin and addition of HCN to acetylene in catalyst solution. 

First made commercially available in Germany in 1936, this elastomer is officially known as acrylonitrile butadiene, and is usually the product of an emulsion polymerization process that combines the two monomers acrylonitrile and butadiene. However, the polymer can also be made in a solution process, and with a variety of monomers. As a specialty polymer, and even though several commercial brands were available, Buna N (as it was first known) was little used until World War II, when the polymer s unique oil and plasticizer resistance and high heat resistance became very important for transportation products. Nitrile rubber also exhibits exceptional adhesion to metallic surfaces and is compatible with a wide range of additives and compounding ingredients. 

Acrylonitrile-butadiene copolymer Nitrile rubber. Buna N NBR... 

Whilst the peroxide-initiated emulsion polymerized polybutadiene had disappointing properties it was found in 1929 that copolymerization of butadiene with styrene and in 1930 with acrylonitrile led to the production of interesting materials. The butadiene-styrene rubber. Buna S, was potentially a general purpose rubber but at that time not competitive with natural rubber. On the other hand the butadiene-acrylonitrile rubber. Buna N, now commonly known as nitrile rubber had certain properties such as oil resistance not shown by natural rubber and commercial production was started about 1935. Commercial production of butadiene-styrene rubber did not commence until 1937 and many things were to happen before it became the world s most used rubber. 

Polyacrylonitrile (PAN) is formed by the peroxide-initiated free-radical polymerization of acrylonitrile (CH2=CH—CN). The major application of PAN is as the fiber Orion. When copolymerized with butadiene, it forms Buna N or nitrile rubber, which is resistant to hydrocarbons and oils. As a copolymer with styrene (SAN), it is a transparent plastic with very good impact strength used for machine components and for molding crockery. As a terpolymer of acrylonitrile-butadiene-styrene (ABS), the plastic is known for its toughness and good strength and finds applications in water lines and drains. 

Synthetic rubbers are made from chloroprene and butadiene which form neoprene and buna, respectively. The copolymer of acrylonitrile with butadiene (1,3) is known as nitrile rubber and styrene with butadiene (1,3) is Buna S. The combination of acrylonitrile, butadiene, and styrene in various formulations is used to form the thermoplastic ABS. 

Styrene-butadiene (Buna 5) and acrylonitrile-butadiene (Buna N) rubbers (Germany)... 

The butadiene-acrylonitrile rubbers were first prepared about 1930 about five years after the initial development of free-radical-initiated emulsion polymerisation. Commercial production commenced in Germany in 1937, with the product being known as Buna N. By the late 1980s there were about 350 grades marketed by some 20 producers and by the early 1990s world production was of the order of 250000 tonnes per annum, thus classifying it as a major special purpose rubber. 

Nitrile rubber (NBR) was first commercialized by I.G. Farbindustry, Germany, in 1937, under the trade name of Buna N. Its excellent balance of properties confers it an important position in the elastomer series. Nitrile rubber, a copolymer of butadiene and acrylonitrile, is widely used as an oil-resistant rubber. The acrylonitrile content decides the ultimate properties of the elastomer. In spite of possessing a favorable combination of physical properties, there has been a continuous demand to improve the aging resistance of NBR due to the tougher requirements of industrial and automotive applications. 

Buna [Butadien natrium] The name has been used for the product, the process, and the company VEB Chemische Werke Buna. A process for making a range of synthetic rubbers from butadiene, developed by IG Farbenindustrie in Leverkusen, Germany, in the late 1920s. Sodium was used initially as the polymerization catalyst, hence the name. Buna S was a copolymer of butadiene with styrene Buna N a copolymer with acrylonitrile. The product was first introduced to the pubhc at the Berlin Motor Show in 1936. Today, the trade name Buna CB is used for a polybutadiene rubber made by Bunawerke Hiils using a Ziegler-Natta type process. German Patent 570, 980. 

Over 5.5 billion pounds of synthetic rubber is produced annually in the United States. The principle elastomer is the copolymer of butadiene (75%) and styrene (25) (SBR) produced at an annual rate of over 1 million tons by the emulsion polymerization of butadiene and styrene. The copolymer of butadiene and acrylonitrile (Buna-H, NBR) is also produced by the emulsion process at an annual rate of about 200 million pounds. Likewise, neoprene is produced by the emulsion polymerization of chloroprene at an annual rate of over 125,000 t. Butyl rubber is produced by the low-temperature cationic copolymerization of isobutylene (90%) and isoprene (10%) at an annual rate of about 150,000 t. Polybutadiene, polyisoprene, and EPDM are produced by the anionic polymerization of about 600,000, 100,000, and 350,000 t, respectively. Many other elastomers are also produced. 

Nitrile rubber - Copolymers of acrylonitrile and butadiene. Same as NBR or Buna-N. 

The first polymerization of isoprene in sealed bottles was reported in 1884 by Tilden. Methyl rubber was thermally polymerized at 70°C — the reaction required 3 to 6 months, giving poor quality products. In 1926 BASF developed sodium-initiated polymerization of butadiene known as Buna (for BUtadiene -I- Natrium). The first successful, general purpose rubbers were copolymers of butadiene with either styrene, Buna-S, or acrylonitrile, Buna-N [Tschunkur and Bock, 1933 Komad and Tschunkur, 1934]. Poly(2-chlorobutadiene), chloroprene [Carothers et ah, 1931], was introduced in 1931 by DuPont. Elastomeric polysulfides [Patrick, 1932] were... 

As a result of the concurrent progress on the polymerization side, Ludwigshafen and Leverkusen agreed in July 1929 to build a semi-technical works plant for Buna at Knapsack, alongside the carbide works. This plan was blocked by Carl Krauch of Oppau, largely because he wanted to wait until Oppau s methane-to-acetylene electric arc process was ready. A few months later, the Buna program was effectively halted by the onset of the Depression, which soon reduced natural rubber prices to minimal levels. When the production of synthetic rubber was revived in Hitler s Third Reich, the weak Buna, which was a sodium-polymerized polybutadiene, had been displaced by the superior copolymers of butadiene with styrene (Buna S) and acrylonitrile (Buna N or Perbunan). 

Hohenstein and Mark [4] reviewed the early development of emulsion and suspension polymerization. Talalay and Magat [5] described work in the former USSR in detail. Dunbrook [6] described how the production of synthetic rubber was organized in the USA during the Second World War. Already in 1933 General nre Rubber had tested Buna S for tyre production, but found it inferior to natural rubber. Nevertheless German production increased from 300 tons per year in 1935 to 5000 tons per year in 1937 in pursuance of the aim of making the country independent of imported raw materials. The oil resistant butadiene-acrylonitrile copolymer Buna N created more interest in the USA and a pilot plant was in operation by the end of 1939. The US government established the Office of the Rubber Reserve in May 1940 primarily to create a stockpile of natural rubber, but the constmction of four plants with a total capacity of 40000 tons per year was authorized. As a consequence of the Japanese occupation of Malaya in 1942 which cut off supplies of natural rubber, the... 

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