Styrene-acrylonitrile copolymer
| Structural formula | |||||||
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| General | |||||||
| Surname | Styrene-acrylonitrile copolymer | ||||||
| other names |
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| CAS number | 9003-54-7 | ||||||
| Monomers / partial structures | Styrene , acrylonitrile | ||||||
| Qualitative molecular formula |
(C 8 H 8 ) n - (C 3 H 3 N) m |
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| PubChem | 62696 | ||||||
| Type of polymer |
Thermoplastic |
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| properties | |||||||
| density |
1.09 g cm −3 (15% by weight acrylonitrile) |
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| Glass temperature |
108 ° C |
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| Elongation at break |
2.5% |
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| safety instructions | |||||||
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||
Styrene-acrylonitrile copolymers ( abbreviation SAN ) are copolymers made from styrene and acrylonitrile .
properties
Styrene-acrylonitrile copolymers have similar properties to polystyrene and are transparent and rigid polymers. A typical composition consists of 70% styrene and 30% acrylonitrile. Products with 19–35% acrylonitrile content and different molar masses are available on the European market . SAN has a higher strength , thermal and scratch resistance than polystyrene and is more chemically resistant , for example to amines , which in turn are a frequent component of plasticizers .
SAN can only be screwed on during assembly; it is not suitable for clipping. SAN is largely dishwasher-safe, but only partially UV-resistant. Most SAN types have food approval from the Federal Institute for Risk Assessment , BfR. Due to the yellowish inherent color (not impairing quality), various shades of blue / gray are available. Opaque colors are also available, in which the high modulus of elasticity of the product and the high scratch resistance come into their own. Glass fiber reinforced types are also available for particularly high rigidity.
By adding polyvinylcarbazole (PVC), a higher heat resistance is achieved. However, plastics with PVC are toxic and therefore not approved for contact with food.
Since styrene-acrylonitrile copolymers are brittle , the synthesis is started together with polybutadiene (graft polymerization) for applications where high impact strength is required . This product is then an acrylonitrile-butadiene-styrene terpolymer (ABS).
Manufacturing
The synthesis takes place as a radical chain polymerization and leads to atactic, random copolymers. Two procedures are common:
- Suspension : As initiator is AIBN used. Suspending agents are hydroxyapatite , talc , methyl cellulose or polyvinyl alcohol . The reaction takes place in 3 h at 20 ° C. The process results in a pearl-shaped product.
- Emulsion polymerization : The initiator is potassium peroxodisulfate , the emulsifiers used are alkyl sulfonates , salts of stearic acid and oleic acid . The reaction takes place at 70 ° C.
The copolymerization parameters of the acrylonitrile / styrene monomer pairing are 0.01 and 0.4, which leads to an arrangement in which very short PS units alternate with individual acrylonitrile units.
processing
Like all styrene polymers, styrene-acrylonitrile polymers are mainly processed by injection molding, and more rarely by extrusion (for films). Heated element and rotary friction welding are possible, but less so are ultrasonic and high-frequency welding.
Applications
- Light guide
- Glazing for industrial doors, sectional doors (e.g. Plustherm system glazing)
- Optic body, e.g. B. Steering angle sensors in automotive engineering
- Kitchen supplies (salad bowl and cutlery, measuring cups, parts for kitchen machines)
- Shower cubicle walls
- Reflectors
- Battery cell jars
- SAN is a raw material for compounding
Norms
- DIN EN ISO 4894-1 Plastics - Styrene / acrylonitrile (SAN) molding compounds - Part 1: Designation system and basis for specifications (ISO 4894-1: 1997); German version EN ISO 4894-1: 1999
- DIN EN ISO 4894-2 Plastics - Styrene / acrylonitrile (SAN) molding compounds - Part 2: Production of test specimens and determination of properties (ISO 4894-2: 1995); German version EN ISO 4894-2: 1999
providers
The SAN market is highly diversified. Large providers in Germany are:
- Styrolution as Luran ®
- Dow Chemical with Tyril® ®
- Polimeri - Kostil ®
Individual evidence
- ↑ Marcos Perez-Blanco, Jeffrey R. Hammons, Ronald P. Danner: Measurement of the solubility and diffusivity of blowing agents in polystyrene . In: Journal of Applied Polymer Science . 116, No. 4, May 15, 2010, pp. 2359-2365. doi : 10.1002 / app.31740 .
- ↑ Mohamed Abo El Wafaa Abdelkarim, Shuji Okadab, Hachiro Nakanishib: Poling and its relaxation studies of polycarbonate and poly (styrene-co-acrylonitrile) doped by a nonlinear optical chromophore . In: Dyes and Pigments . 69, No. 3, 2006, pp. 239-244. doi : 10.1016 / j.dyepig.2005.03.014 .
- ↑ V. Realinho, M. Antunes, D. Arencón, AI Fernández, JI Velasco: Effect of a dodecylsulfate-modified magnesium-aluminum layered double hydroxide on the morphology and fracture of polystyrene and poly (styrene-co-acrylonitrile) composites . In: Journal of Applied Polymer Science . 111, No. 5, March 2009, pp. 2574-2583. doi : 10.1002 / app.29288 .
- ↑ a b Data sheet Poly (styrene-co-acrylonitrile), average M at Sigma-Aldrich , accessed on October 8, 2013 ( PDF ).
- ↑ Bernd Tieke, Makromolekulare Chemie , 3rd edition, Wiley-VCH, Weinheim, 2014, p. 173.
- ^ Cowie, Chemistry and Physics of Synthetic Polymers, Vieweg 1997, p. 119
- ↑ Christian Bonten: Plastics Technology Introduction and Basics , Hanser Verlag, 2014