Antioxidant permanence, factors

ANTIOXIDANT PERMANENCE EFFECTS OF CHEMICAL AND PHYSICAL FACTORS... 

As with thermal stabilizers, photostabilizers must satisfy basic chemical and physical requirements (see the section titled ""Antioxidant permanence effects of chemical and physical factors ). In addition, they must be photo-stable, i.e., stable to UV-light, to withstand continuous periods of UV-exposure, without being prematurely destroyed or effectively transformed into sensitizing products. There are essentially three classes of compounds that are categorized as photostabilizers/ photoantioxidants UV-absorbers and pigments, peroxide decomposers including nickel complexes, and sterically hindered amine light stabilizers. 

Overall, all aspects of environmental effects, antioxidant safety, optimum concentration levels and antioxidant permanence under the specified service conditions have to be considered and balanced with the initial cost of the antioxidant the cost effectiveness of antioxidant packages is a decisive factor in all industrial apphcations. 

The physical behavior of an antioxidant is a major factor affecting its permanency, efficiency, and acceptability, especially when the polymer (e.g., fibers, films) artifact is placed directly in contact with aggressive environments, e.g., organic solvents including dry cleaning solvents, hot water and detergents, hot oils, acids, fatty food, hot air, and intense solar radiation. Physical factors, which control the permanence and efficacy of an antioxidant include distribution, solubility, diffusivity, volatility, and leachability. 

Ham et al 1982), leading to permanent blindness for which no treatment exists. A number of factors suppress or enhance light damage to the eye, including oxygen, antioxidants, repair mechanisms, and biophysical mechanisms. 

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