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In industrial chemistry, a stabilizer or stabiliser is a chemical that is used to prevent degradation. Above all, heat and light stabilizers are added to
plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...
and
rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Types of polyisoprene ...
materials because they ensure safe processing and protect products against aging and weathering. In particular
polyvinyl chloride Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: vinyl or polyvinyl; abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons of ...
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 is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...
(calcium-
zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...
and organo-calcium),
lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
, 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.


Polymers (plastics and elastomers)

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: *
antioxidant Antioxidants are Chemical compound, compounds that inhibit Redox, oxidation, a chemical reaction that can produce Radical (chemistry), free radicals. Autoxidation leads to degradation of organic compounds, including living matter. Antioxidants ...
s 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 () (or trioxygen) is an Inorganic compound, inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , break ...
( 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 Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
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

*
emulsifier An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Althou ...
s and
surfactant Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word ''surfactant'' is a Blend word, blend of "surface-active agent", coined in ...
s, for stabilization of emulsions


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. 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.


See also

* Corrosion inhibitor * Stabilizers for polymers


References

Chemical kinetics Chemical compounds Material protection {{chem-compound-stub