Copolymer of isobutylene and isoprene

Butyl Rubber. Butyl mbber was the first low unsaturation elastomer, and was developed ia the United States before World War II by the Standard Oil Co. (now Exxon Chemical). It is a copolymer of isobutylene and isoprene, with just enough of the latter to provide cross-linking sites for sulfur vulcanization. Its molecular stmcture is depicted ia Table 1. 

Isobutylene-based elastomers include HR, the copolymer of isobutylene and isoprene, halogenated HR, star-branched versions of these polymers, and the terpolymer isobutylene-p-methylene styrene-bromo-p-methyl styrene (BIMS). A number of recent reviews on isobutylene-based elastomers are available [33-35]. 

Buna-S Elastomeric copolymer of butadiene and styrene, butyl rubber Elastomeric copolymer of isobutylene and isoprene. 

To this category belong homopolymers of polyisobutylene, copolymers of isobutylene and isoprene (butyl rubber), chlorobutyl, and bromobutyl. All these have been produced commercially for decades. 

J.M. Downward, USP 3018201 (1962) CA 56, 13153(1962) (Gelatinous expl compns afe provided by mixts contg expls such.as NC, NS or RDX and a nonexplosive gel consisting of water-irwsol petroleum hydrocarbons such as a vulcanized copolymer of isobutylene and isoprene)... 

Butyl rubber - A copolymer of isobutylene and isoprene rubber ASTM designation HR butyl rubber is the common name for such materials. 

Known as MR. butyl rubber is a copolymer of isobutylene and isoprene. The elastomers contain only (1.5 2.5 mole 9r of isoprene. This is introduced to effect sufficient unsaturatinn to make the rubber vulcanizublc. Polymerizations are usually earned out at low temperature (-80 to -1(KJ C) with methyl chloride as solvent. Anhydrous aluminum chloride and a trace of water serve as catalyst. 

RUBBER (Synthetic). Any of a group of manufactured elastomers that approximate one or more of the properties of natural rubber. Some of these aie sodium polysulfide ( Thiokol ). polychloiopiene (neoprene), butadiene-styrene copolymers (SBR), acrylonitrilebutadiene copolymers (nitril rubber), ethvlenepropylene-diene (EPDM) rubbers, synthetic poly-isoprene ( Coral, Natsyn ), butyl rubber (copolymer of isobutylene and isoprene), polyacrylonitrile ( Hycar ). silicone (polysiloranei. epichlorohy-drin, polyurethane ( Vulkollan ). 

Butyl rubber is one of the older synthetic rubbers, having been developed in 1937. Because of the saturated nature of a polyolefin elastomer, the commercial polymer is actually a copolymer of isobutylene and isoprene. The isoprene is added to provide cure sites. In addition, halogenated (bromo or chloro) derivatives are available. 

The importance of isobutylene in the petrochemical industry is well recognized. Isobutylene is used on a large scale for the production of (i) methacrolein by direct oxidation, (ii) polyisobutylene by polymerization, (iii) synthetic rubber (a copolymer of isobutylene and isoprene), and (iv) methyl tert-butyl ether (MTBE, a gasoline octane-number enhancer) by reaction with methanol. 

Depending on the grade of polymer, polychloroprene can be vulcanized by zinc oxide or magnesium oxide. Tetramethylthiuram disulfide can serve as a retarder. Polychloroprene is inferior to NBR for oil resistance but is still significantly better than natural rubber, SBR, or BR. Like NBR it also finds extensive use in such products as oil seals, gaskets, hose linings, and automotive engine transmission belts where resistance to oil absorption is important. Butyl rubbers are a copolymer of isobutylene and isoprene ... 

Synonyms 1,3-Butadiene-2-methyl polymer with 2-methyl-l-propene Butyl rubber HR Isobutylene/isoprene copolymers 3-Methyl-1,3-butadiene polymer with 2-methyl-1 -propene Poly (isobutylene-co-isoprene) Definition Copolymer of isobutylene and isoprene monomers Formuia (CsHs C4H8),... 

The physical aspects of ozone cracking are clearly seen in the case of the predominantly saturated butyl rubber (HR), a copolymer of isobutylene and isoprene containing - 1-3% isoprene. Although the chemistry is the same as for its diene rubber counterpart, IR, butyl rubber is much more resistant to ozone cracking. Unsaturated elastomers must be stretched for ozone cracking to occur. 

Butyl rubber (HR) is an isobutylene-based rubber which includes copolymers of isobutylene and isoprene, halogenated butyl rubbers, and isobutylene/p-methylstyrene/bromo-p-methylstyrene terpoly-mers. HR can be slurry polymerized from isobutylene copolymerized with small amounts of isoprene in methyl chloride diluent at -130 to - 148°F (-90 to - 100°C). Halogenated butyl is produced by dissolving butyl rubber in a hydrocarbon solvent and introducing elemental halogen in gas or liquid state.Cross-linked terpolymers are formed with isobutylene + isoprene + divinylbenzene. 

Thomas reduced the cold flow of polyisobutylene by blending it with about 10% of natural rublter in the early 1930 s. However, the copolymer of isobutylene and isoprene was not produced until the late 1930 s, after many years of researdi efforts. This important copolymer was patented by Thomas and Sparks [U.S. Pat. 2,356,128 (1940)]. This new elastomer was also described in articles by R.M. Thomas and co-workers in 1940-41 in several journals including Ind. Eng. Chem.. 32. 1283 (1940). 

While progress was erratic until about the 1930 s, synthetic elastomers were not only born, but expanding technically. It is perhaps notable that the first few products of the synthetic elastomer industry s resurgence then brought forth elastomers which offered environmental resistances vastly superior to natural products. Most notable of these were Thiokol (polysulfides) in 1929, neoprene (polychloroprene) in 1931, Buna N (copolymers of butadiene and acrylonitrile) in 1937, and butyl (copolymer of isobutylene and isoprene) in 1940. Many more were to follow. 

Butyl rubber is a copolymer of isobutylene and isoprene. It is a product of research carried out in both Germany and the United States in the 1930s. 

Butyl rubber is a copolymer of isobutylene and isoprene as shown in Figure 6.22. 

Standard or unmodified grades of butyl rubber are linear, amorphous, gel-free copolymers of isobutylene and isoprene. Individual grades differ from each other in functionality, the level of unsaturation varying with the ratio of isoprene to isobutylene, raw polymer viscosity (a function of molecular... 

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