Stabilizer (chemistry)
{{Short description|Chemical used to prevent degradation}}
In industrial chemistry, a stabilizer or stabiliser is a chemical that is used to prevent degradation.{{cite encyclopedia|title=Plastics, Additives|encyclopedia=Ullmann's Encyclopedia Of Industrial Chemistry|author1=Rainer Wolf|author2=Bansi Lal Kaul|year=2000|doi=10.1002/14356007.a20_459|isbn=3527306730 }} Above all, heat and light stabilizers are added to plastic and rubber materials because they ensure safe processing and protect products against aging and weathering. In particular polyvinyl chloride would not be possible without stabilizers (PVC is one of the most important plastics and used for pipes, window frames and many other products).
In economic terms the most important product groups on the market for stabilizers are compounds based on calcium (calcium-zinc and organo-calcium), lead, and tin stabilizers as well as liquid and light stabilizers (HALS, benzophenone, benzotriazole). Cadmium-based stabilizers largely vanished in the last years due to health and environmental concerns. In 2023, almost half of all polymer stabilizers sold worldwide were based on calcium.{{cite web |last=Ceresana |date= |title=Market Study: Stabilizers |url=https://ceresana.com/en/produkt/stabilizers-market-report-world |access-date=25 October 2024 |website=Ceresana - market research}}
Polymers (plastics and elastomers)
{{main|Stabilizer for polymers}}
Stabilizing additives for plastics are produced in different forms. The trend is towards fluid systems, pellets, and increased use of masterbatches. There are monofunctional, bifunctional, and polyfunctional stabilizers. Some kinds of stabilizers are:{{cite book|last1=Zweifel|first1=Hans|last2=Maier|first2=Ralph D.|last3=Schiller|first3=Michael|title=Plastics additives handbook|date=2009|publisher=Hanser|location=Munich|isbn=978-3-446-40801-2|edition= 6th}}{{cite journal |last1=Singh |first1=Baljit |last2=Sharma |first2=Nisha |title=Mechanistic implications of plastic degradation |journal=Polymer Degradation and Stability |date=March 2008 |volume=93 |issue=3 |pages=561–584 |doi=10.1016/j.polymdegradstab.2007.11.008}}
- antioxidants these prevent autoxidation of materials and come in 3 primary forms.
- Oxygen scavengers (primarily phosphite esters such as tris(2,4-di-tert-butylphenyl)phosphite) are commonly used during the initial processing of the plastic.
- Persistent radical scavengers prevent or slow the photo-oxidation of polymers. Traditionally these are alkylated phenols such as butylated hydroxytoluene but now also include hindered amine light stabilizers (HALS)
- Antiozonants prevents or retards the degradation of polymers caused by ozone (ozone cracking)
- sequestrants, forming chelate complexes and inactivating traces of metal ions that would otherwise act as catalysts
- ultraviolet stabilizers are used to protect polymers from effects of ultraviolet radiation and come to 2 main types.
- UV absorbers which essentially act the same way as sunscreens
- Quenchers, which dissipate the radiation energy as heat instead of letting it break chemical bonds; often organic nickel salts, e.g. nickel phenolates
Paints
- emulsifiers and surfactants, for stabilization of emulsions{{Citation needed|date=January 2021}}
Food
{{Main article|Stabiliser (food)}}
In foods, stabilizers prevent spoilage. Classes of food stabilizers include emulsifiers, thickeners and gelling agents, foam stabilizers, humectants, anticaking agents, and coating agents.Erich Lück, Gert-Wolfhard von Rymon Lipinski "Foods, 3. Food Additives" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. {{doi| 10.1002/14356007.a11_561}}
File:BigPhosphite31570-04-4.png|Tris(2,4-di-tert-butylphenyl)phosphite is a widely used stabilizer in polymers.
File:HALSgeneric.png|Partial structure of typical hindered amine light stabilizers, widely used to protect automotive paints from degradation by UV-light.
File:Salpn.png|Salpn is a typical metal deactivator used as a fuel additive to suppress oxidation processes that lead to gums and solids. Metal deactivators like salpn form stable complexes with the metals, suppressing their catalytic activity.{{Ullmann|author = Dabelstein, W.|author2 = Reglitzky A.|author3 = Schutze A.|author4 = Reders, K.|title = Automotive Fuels}}
See also
References
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