View source for Styrene-butadiene

{{chembox
| Name = Styrene-butadiene
| ImageFile = SBR.svg|right|243px|thumb|Chemical structure of styrene-butadiene
| ImageSize = 250
| IUPACName = 
| SystematicName = 
| OtherNames = 
| Section1 = {{Chembox Identifiers
| Abbreviations = 
| CASNo = 9003-55-8
| EINECS = 
| EINECSCASNO = 
| PubChem = 
| SMILES = 
| InChI = 
| RTECS = 
| MeSHName =
| ChEBI =
| KEGG = 
| ATCCode_prefix = 
| ATCCode_suffix = 
| ATC_Supplemental =}}
| Section2 = {{Chembox Properties
| Formula = 
| MolarMass = 
| Appearance = 
| Density = 
| MeltingPt = 
| Melting_notes = 
| BoilingPt = 
| Boiling_notes = 
| Solubility = 
| SolubleOther = 
| Solvent = 
| LogP = 
| VaporPressure = 
| HenryConstant = 
| AtmosphericOHRateConstant = 
| pKa = 
| pKb = }}
| Section3 = {{Chembox Structure
| CrystalStruct = 
| Coordination = 
| MolShape = }}
| Section4 = {{Chembox Thermochemistry
| DeltaHf = 
| DeltaHc = 
| Entropy = 
| HeatCapacity = }}
| Section5 = {{Chembox Pharmacology
| AdminRoutes = 
| Bioavail = 
| Metabolism = 
| HalfLife = 
| ProteinBound =
| Excretion = 
| Legal_status = 
| Legal_US = 
| Legal_UK = 
| Legal_AU = 
| Legal_CA = 
| PregCat = 
| PregCat_AU = 
| PregCat_US = }}
| Section6 = {{Chembox Explosive
| ShockSens = 
| FrictionSens = 
| ExplosiveV = 
| REFactor = }}
| Section7 = {{Chembox Hazards
| ExternalMSDS = 
| EUClass = 
| EUIndex = 
| MainHazards = 
| NFPA-H = 
| NFPA-F = 
| NFPA-R = 
| NFPA-O = 
| RPhrases = 
| SPhrases = 
| RSPhrases = 
| FlashPt = 
| Autoignition = 
| ExploLimits = 
| LD50 =
| PEL = }}
| Section8 = {{Chembox Related
| OtherAnions = 
| OtherCations = 
| OtherFunctn = 
| Function = 
| OtherCpds = }}
}}
'''Styrene-Butadiene''' or '''Styrene-Butadiene-Rubber''' (SBR) is a [[synthetic rubber]] [[copolymer]] consisting of [[styrene]] and [[butadiene]]. It has good [[Wear#Abrasive wear|abrasion]] resistance and good aging stability when protected by additives, and is widely used in car [[tires]], where it is blended with [[natural rubber]]. It was originally developed prior to [[World War II]] in Germany,<ref>http://www.wisegeek.com/what-is-styrene-butadiene-rubber.htm</ref> but during the War was used extensively by the USA to replace natural rubber supplies from the far-east, that had been captured by the Japanese.

SBR can be produced from solution or as emulsion. In both instances, the reaction is via free radical polymerization. Pressure reaction vessels are required and usually charged with the two monomers, a free radical acid and a chain transfer agent such as an alkyl mercaptan. The latter prevents high molecular weight and high viscosity product from forming. High styrene-content rubbers are hard, since the Tg (glass transition temperature) of butadiene is extremely low. The production process is initiated by [[sodium]].  

It is not to be confused with a [[thermoplastic elastomer]] made from the same monomers, styrene-butadiene [[block copolymer]]. 

==Buna S==
The material was initially marketed with the brand name '''Buna S'''. It derives this name from: '''Bu''' for [[butadiene]], '''Na''' for sodium (natrium in Latin, Natrium in German), and '''S''' for [[styrene]].<ref>http://www.pslc.ws/macrog/exp/rubber/synth/buna.htm</ref><ref>http://www.degussa-history.com/geschichte/en/inventions/buna</ref>

==Properties==
*[[Glass transition temperature]] approximately {{convert|-55|°C|°F}}, but varies with styrene content<ref>Gent, A. N.; Campion, R. P.; American Chemical Society. Division of Rubber, ''Engineering With Rubber: How to Design Rubber Components''; Munich: Hanser Publishers: 1992.</ref>
*Possible temperature range of use: approximately {{convert|-40|to|100|C|F}}
*Chemical Type: styrene-butadiene ([[copolymer]])
*Trade names (common): GRS, Buna S, SBR
*Elongation (%): 450-500
*[[Shore durometer|Shore A hardness]]: 50-90<ref>{{cite web |url=http://www.satoriseal.com/styrene_butadiene.htm |title=Styrene Butadiene |publisher=Satori Seal Corporation |accessdate=2009-02-14}}</ref>
*Major application characteristics: good physical properties; excellent abrasion resistance; but sensitive to oil, wastewater and [[ozone]]; electrical properties good, but not outstanding

==Applications==
The [[elastomer]] is used widely in pneumatic [[tire]]s, shoe heels and soles, [[gasket]]s and even [[chewing gum]]. It is a commodity material which competes with [[natural rubber]]. Latex (emulsion) SBR is extensively used in [[coated paper]]s, being one of the most cost-effective resins to bind pigmented coatings. It is also used in building applications, as a sealing and binding agent behind renders as an alternative to PVA, but is more expensive. In the latter application, it offers better durability, reduced shrinkage and increased flexibility, as well as being resistant to emulsification in damp conditions.

Additionally, it is used in some rubber [[cutting boards]].

==See also==
*[[elastomer]]
*[[ozone cracking]]
*[[Tire|tyre]]
*[[synthetic rubber]]

== References ==
{{reflist}}

{{DEFAULTSORT:Styrene-Butadiene}}
[[Category:Copolymers]]
[[Category:Elastomers]]
[[Category:Polymers]]

[[de:Styrol-Butadien-Kautschuk]]
[[es:Caucho estireno-butadieno]]
[[fr:Styrène-butadiène]]
[[it:Gomma SBR]]
[[pt:Borracha de butadieno estireno]]
[[ja:スチレン・ブタジエンゴム]]
[[fi:Buna]]
[[vi:Cao su styren-butađien]]
[[Category:2Fix]]