Rubber, methyl

Methyl-ierung, -isiertmg, /. methylation. -jodid, n. methyl iodide, iodomethane. -kautschuk, m. methyl rubber. Methylostarke,/. methylstarch. Methyl-oxydhydrat, n. methyl hydroxide (meth-... 

CH2C(CH3)C(CH3)CH2, a diolefin from which was manufactured methyl rubber in Germany during World War I. 

Poly(styrene) 1839 1930 Thermoplastics, foams Methyl rubbers 1912 1915 Elastomers... 

X-ray diffraction shows cotton, silk and asbestos to be crystalline products (Nishikawa and Ono, later confirmed by Herzog and Polanyi, 1920) Production of "methyl-rubber" on commercial scale in Germany due to lack of natural rubber during World War I... 

FIG. 18.3 Activation energy of diffusion as a function of Tg for 21 different polymers from low to high temperatures, ( ) odd numbers (O) even numbers 1. Silicone rubber 2. Butadiene rubber 3. Hydropol (hydrogenated polybutadiene = amorphous polyethylene) 4. Styrene/butadiene rubber 5. Natural rubber 6. Butadiene/acrylonitrile rubber (80/20) 7. Butyl rubber 8. Ethylene/propylene rubber 9. Chloro-prene rubber (neoprene) 10. Poly(oxy methylene) 11. Butadiene/acrylonitrile rubber (60/40) 12. Polypropylene 13. Methyl rubber 14. Poly(viny[ acetate) 15. Nylon-11 16. Poly(ethyl methacrylate) 17. Polyethylene terephthalate) 18. Poly(vinyl chloride) 19. Polystyrene 20. Poly (bisphenol A carbonate) 21. Poly(2,6 dimethyl-p.phenylene oxide). 

Methyl rubber, obtained by polymerization of this monomer, was expensive and had inferior properties, and its manufacture was discontinued at the end of World War I. By the time World War II again shut off access to natural rubber, Germany had developed better synthetic rubbers based upon butadiene... 

Dimethylbutene, which is obtained in about 70% yield, represents a new and valuable olefin available by a catalytic process. Its dehydrogention product—2,3-dimethylbutadiene—was once used to produce so-called methyl rubber. The new synthesis of 2,3-dimethylbutene may renew interest in methyl rubber or other synthetic applications of dimethylbutadiene. 

During World War I German chemists, whose coxmoy was cut off from its sources of natural rubber by the British blockade, polymerized 3-methyl-isoprene (2,3-dimethyl-1,3-butadiene) units, (CH2=C(CH3)C(CH3)=CH2), obtained from acetone, to form an inferior substitute called methyl rubber. By the end of the war Germany was producing 15 tons (13.6 metric tons) of this rubber per month. The USSR (Union of Soviet Socialist Republics), which built a pilot plant at Leningrad (now St. Petersburg) in 1930 and three factories in 1932 and 1933, was the first country to institute a full-scale synthetic rubber industry. 

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... 

Even while he was busy with the manufacture of ethylene oxide, Walter Reppe was also involved with the development of Buna synthetic rubber. In 1926, the newly formed I.G. Farben decided to embark on the industrial synthesis of rubber, despite the poor quality of the methyl rubber made during World War I. This time, however, it was agreed that butadiene would be used. Several routes to butadiene were investigated, including decyclization of cyclohexene (a retro-Diels-Alder reaction), but the so-called four-step process (Vierstufen Verfahren) soon won out. This was partly because it used acetylene, and hence surplus carbide from cyanamide manufacture, but also because it drew on the steps - and hence the momentum - of the BASF butanol synthesis. As a member of the former butanol group, Reppe was a natural candidate for the four-step process project. 

Apart from the rather expensive and inferior methyl rubber produced in Germany during World War I, the first industrial production of synthetic rubbers took place in 1932, with polybutadiene being produced in the USSR, from alcohol derived from the fermentation of potatoes, and neoprene (polychloroprene) being produced in the USA from acetylene derived from coal. In 1934 the first American car tyre produced from a synthetic rubber was made from neoprene. In 1937 butyl rubber, based on polyisobutylene, was discovered in the USA. This material has a lower resilience than that of natural rubber but far surpasses it in chemical resistance and in having a low permeability to gases. The chemical structures of these materials are shown in fig. 6.10. 

During World War I, poly (dimethyl butadiene) was manufactured under the name methyl rubber as a substitute for the natural rubber that the Central Axis Powers lacked. H-type poly(dimethyl butadiene) was obtained by letting the monomer stand for three months in ventilated metal drums. The white, solid crystalline material thus obtained by popcorn polymerization becomes... 

Early attempts at preparations of synthetic rubbers resulted in developments of elastomers from 2,3-dimethylbutadiene. The material, called methyl rubber, was claimed to yield better elastomeric properties than polybutadiene. Methyl rubber was produced in Germany during World War I where the monomer was prepared from acetone. The polymerizations were carried out by free-radical mechanism and anionically, using sodium metal dispersions for initiatimi. Later, it was demonstrated that 2,3-dimethyl polybutadiene can be polymerized to very high cis-, A polymer with Ziegler-Natta catalysts [125, 126]. 

During World War I, poly(dimethyl butadiene) (methyl rubber) was manufactured as a substitute for the natural rubber that the Central Powers lacked when the war ended, its production was curtailed because of its relatively poor properties and high cost. 2,3-Dimethyl butadiene is produced from acetone via pinnacol ... 

Methyl rubber Poly(2,3-dimethylbutadiene) Bayer, Germany (World War I)... 

The first polymerization of isoprene in sealed bottles was reported in 1884 by Tilden. Methyl rubber was thermally polymerized at 70 °C - the reaction... 

Methyl rubber n, Poly(2,3-dimethylbuta-diene). Manufactured by Bayer, Germany. a-Methylstyrene n. C6H5C(CH3)=CH2. A colorless liquid, easily polymerizable by heat or with catalysts, and typically... 

The pol)nnerizations of 2,3-dlmethy1-1,3-butadiene with lanthanide coordination catalysts are listed in Table 3. In contrast to the conventional methyl rubber produced by emulsion polymerization, polymers obtained with lanthanide catalysts were not rubbery materials. The polymer obtained was a highly crystalline, white powder with a sharp melting point of 192-195 C, as measured by DSC (Figure 15). The pol)nner was insoluble in cyclohexane and toluene, but very soluble in hot trichlorobenzene. The appearance and... 

Butadiene was first prepared in 1863, and its conjugated structure was proposed in 1886 (1,2). However, the ability of butadiene to polymerize was not recognized until almost 50 years later when, in 1909, a rubbery polymer was first reported as being prepared from butadiene via thermal polymerization (3). Shortly thereafter, the more controlled poljnnerization of butadiene initiated by sodium metal was reported in 1911 (4). During this time period, a sharp rise in natural rubber prices prompted the Bayer Corp. to develop methyl rubber from... 

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