Preparation, photochemical stability and photostabilizing efficiency of adducts of 1,8-naphthaleneimide and hindered amine stabilizers in polymer matrices

Adducts of 1,8-naphthaleneimide and hindered amine stabilizer (HAS) such as 1-R-substituted-2,2,6,6-tetramethyl-4-aminopiperidine were prepared where R is -H, -O ., -OH, -COCH3 and -OCOCH3. The photochemical stability of addu cts was determined at photolysis in isotactic polypropylene, polystyrene an d polyvinylchloride. Their photostabilizing efficiency was determined at ph otooxidation of isotactic polypropylene. The photochemical stability of the adducts is low in all matrices. The N-oxy derivative was the most stable i n all matrices. The photolysis of all derivatives is the slowest in polysty rene. Intramolecularly combined chromophore/HAS are less effective stabiliz ers than in 1:1 mixture of separated components. The 1,8-naphthaleneimide c hromophore decreases the stabilization efficiency of hindered amine structu ral units as compared to its absence. (C) 1998 Elsevier Science Ltd. All ri ghts reserved.