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 adducts was determined at photolysis in isotactic polypropylene, polystyrene and polyvinylchloride. Their photostabilizing efficiency was determined at photooxidation of isotactic polypropylene. The photochemical stability of the adducts is low in all matrices. The N-oxy derivative was the most stable in all matrices. The photolysis of all derivatives is the slowest in polystyrene. Intramolecularly combined chromophore/HAS are less effective stabilizers than in 1:1 mixture of separated components. The 1,8-naphthaleneimide chromophore decreases the stabilization efficiency of hindered amine structural units as compared to its absence. (C) 1998 Elsevier Science Ltd. All rights reserved.