Styrene maleic anhydride: Difference between revisions

| CASNo_Ref = {{cascite|correct|CAS}}

| Density = 1.080 g/cm³³

'''Styrene maleic anhydride''', also known as ('''SMA'''or'''SMAnh,''') is a synthetic [[polymer]] that is built-up of [[styrene]] and [[maleic anhydride]] [[monomers]]. The monomers arecan be almost perfectly alternating, making it an alternating [[copolymer]],<ref>{{cite journal |last1=Hill |first1=David J. ItT. |last2=O'Donnell |first2=James H. |last3=O'Sullivan |first3=Paul W. |title=Analysis of the mechanism of copolymerization of styrene and maleic anhydride |journal=Macromolecules |date=1 January 1985 |volume=18 |issue=1 |pages=9–17 |doi=10.1021/ma00143a002|bibcode=1985MaMol..18....9H }}</ref> but (random) copolymerisation with less than 50% maleic anhydride content is also possible. The polymer is formed by a [[radical polymerization]], using an [[organic peroxide]] as the initiator. The main characteristics of SMA copolymer are its transparent appearance, high heat resistance, high dimensional stability, and the specific reactivity of the anhydride groups. The latter feature results in the solubility of SMA in alkaline (water-based) solutions and dispersionsdispersion.

SMA is available in a broad range of molecular weights and maleic anhydride (MA) contents. In a typical combination of those two properties, SMA is available as a crystal clear granule that can be used in a broadwide rangevariety of applications. SMA polymers with a high [[molecular weight]] are widely used in engineering plastic applications, normally in the impact modified and optional [[glass fibre]] filled variants. Alternatively, SMA is applied using its transparency in combination with other transparent materials like [[Poly(methyl methacrylate)|PMMA]] or the heat resistancyresistance to heat-boost other polymers materials like [[Acrylonitrile butadiene styrene|ABS]] or [[PVC]]. The solubility of SMA in alkaline solutions makes it suitable for various applications in the field of sizings (paper), binders, dispersants and coatings. The specific reactivity of SMA makes it a suitable agent for compatibilizing normally incompatible polymers (e.g. ABS/PA blends) or cross-linking.

The glass transition temperature of Styrene maleic anhydride is 130 - 160 &nbsp;°C.

There are only a few commercial suppliers of SMA polymers. The 2three major producers are PolyscopeSolenis Polymers(Scripset), Aurorium (Xiran), Sartomer (SMA). [[Nova Chemicals]] (Dylark) is no longer produced. While the Sartomer product range covers low molecular weight products with high MA contents (and sometimes chemically modified), the Nova materials are high molecular products with low MA content (and mainly impact modified). and PolyscopeAurorium's Xiran product range covers the areafull inspectrum betweenof (withSMA somepolymers, overlap;including also in impactchemically modified grades)types. Each of those products have their own specific features.

SMA can be combined with the solvent [[dimethylsulfoxide]] (DMSO) in an application known as [[reversible inhibition of sperm under guidance]] (RISUG).<ref>{{cite web|title=RISUG|url=http://malecontraceptives.org/methods/risug.php|website=MaleContraceptives.org|publisher=International Male Contraception Coalition|accessdateaccess-date=12 September 2014}}</ref> The process is under phase III clinical trials in India and is a non-surgical method of male sterilization that is inexpensive, highly effective, and reversible. It involves an injection of the solution into each of the patient's [[Vas deferens]], which forms a layer around the vas walls partially (but not completely) blocking the flow of sperm cells. As cells pass by the substance, they are rendered inactive. If approved for widespread application, it could provide an alternative to the current two major methods of male contraception: [[condom]]s or [[vasectomy|vasectomies]].<ref>http{{cite magazine |last1=Gifford |first1=Bill |title=The Revolutionary New Birth Control Method for Men |url=https://www.wired.com/magazine/2011/04/ff_vasectomy/ |magazine=[[Wired (magazine)|Wired]] |access-date=21 July 2023 |archive-url=https://web.archive.org/web/20110430104028/https://www.wired.com/magazine/2011/04/ff_vasectomy/ |archive-date=Apr 30, 2011 |language=en |date=April 26, 2011}}</ref>

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