Stabilizers for Irradiated Systems

Carbon black can be tolerated in a limited number of formulations where color is not a criterion. The pigment not only absorbs light, but is also reactive with those free-radical species that might be formed. Wire and cable insulation and pipe for outdoor applications can be protected this way. Films for mulching and water con-taimnent in ponds may be made from polyethylene containing carbon black. Five UV absorbers and their corresponding transmission curves are shown in Table 12.3 and 

Alkyl-2-cyano-3-phenyl cinnamate (substituted acrylonitrile) 

Source Cipriani, L. R, and J. R Hosier, Mod. Plast., 450A, Encycl. Issue), 406, September 1967. 

Phenyl salicylate has the common name salol. In addition to its use as a stabilizer in polymers, salol is used at concentrations of about 1%-10% in suntan oils and ointments, as are other absorbers. The function of the stabilizer in such a situation is the same as in the polymer, to decrease the concentration of skin-damaging radiation. Toxicity and reactivity take on a personal and obvious importance for this application. Suntan oils illustrate one way in which stabilizers can be used. If the UV absorber is in a thin layer on the surface, the article is protected to a greater extent than if it is dispersed throughout. Occasionally this can be done, as when multiple coats of lacquer are applied to furniture. All the UV absorbers can be put in the top coat. When articles are to be molded, however, it is not economical to coat separately, so the UV absorber is mixed in with the other ingredients. 

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