Possibilities and limits of synergism with light stabilizers in polyolefins 2. UV absorbers in polyolefins

Specific combinations of UV absorbers of different classes show pronounced synergism in polyolefins. The effects depend on the particular combination and sometimes the particular polyolefin. Combinations of an oxanilide with a benzophenone or a benzotriazole or a hydroxyphenyltriazine are systematically synergistic, in polyethylene and in polypropylene. The same holds for combinations of a benzophenone with a hydroxyphenyltriazine. This is not so for combinations of benzotriazole with hydroxyphenyltriazine UV absorbers. The data show them to yield mainly just additive effects. Combinations of benzophenones with benzotriazoles show complex behavior depending on the particular polyolefin. The ternary combinations of the UV absorbers examined are mainly synergistic. The reasons for the results are discussed.