Stabilizer (chemistry)

In industrial chemistry, a stabilizer is a chemical that is used to prevent degradation.^[1] Heat and light stabilizers are added to plastics and elastomers because they ensure safe processing and protect products against aging and weathering. The trend is towards fluid systems, pellets, and increased use of masterbatches. There are monofunctional, bifunctional, and polyfunctional stabilizers. 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.^[2]

• Representative Stabilizers
• 
  Tris(2,4-di-tert-butylphenyl)phosphite is a widely used stabilizer in polymers.
• 
  Partial structure of typical hindered amine light stabilizers, widely used to protect automotive paints from degradation by UV-light.
• 
  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.^[3]

Polymers

Some kinds of stabilizers are:

• antioxidants, preventing oxidation of materials. Phosphite esters are often used.
• sequestrants, forming chelate complexes and inactivating traces of metal ions that would otherwise act as catalysts
• ultraviolet stabilizers, protecting materials, especially plastics, from effects of ultraviolet radiation. For example, benzotriazole is added to polycarbonates to prevent degradation as indicated by cracking and yellowing.
  • UV absorbers, chemicals absorbing ultraviolet radiation and preventing it from penetrating the materials; principally the same as sunscreens
  • quenchers, dissipating the radiation energy as heat instead of letting it break chemical bonds; often organic nickel salts, e.g. nickel phenolates
  • scavengers, eliminating the free radicals formed by ultraviolet radiation; often hindered amine light stabilizers (HALS)

Paints

• emulsifiers and surfactants, for stabilization of emulsions

Food

In foods, prevent spoilage. Classes of food stabilizers include "emulsifiers, thickeners and gelling agents, foam stabilizers, humectants, anticaking agents, and coating agents."^[4]

See also

• Corrosion inhibitor
• Stabilizers for polymers

References