Photostabilization of commercial polypropylene by a hindered amine stabilizer

The photostabilization of commercial polypropylene by a hindered amine stabilizer is examined by luminescence and ESR spectroscopy. The presence of the amine stabilizer inhibits the photolysis of the α,β unsaturated carbonyl impurity groups present in the polymer. Examination by ESR, of the stabilized polymer before and after irradiation shows the development of a highly stabilized free radical indicating that the stabilizer can act as an ultraviolet stable antioxidant. Possible mechanisms whereby the hindered amine inhibits the photolysis of the α,β unsaturated carbonyl groups are discussed.