Photostabilization of commercial polypropylene by hindered piperidine compounds: An ESR and luminescence study

✍ Scribed by N.S. Allen; J.F. McKellar

• Publisher: Elsevier Science
• Year: 1980
• Tongue: English
• Weight: 255 KB
• Volume: 16
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(80)90086-5

✦ Synopsis

The photostabilization of commercial polypropylene by a hindered piperidine stabilizer, bis [2,2,6,6-tetramethyl-4-piperidinyll sebacate (I) and by a model N-oxy radical compound, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxy (!1) is examined using ESR and luminescence spectroscopy. ESR spectroscopy shows that ! operates through the formation of a stable nitroxyl radical in the polymer. On the other hand, il disappears rapidly during the early stages of photo-oxidation but continues to act as an effective stabilizer. A low steady-state equilibrium concentration of nitroxyl radicals is believed to be responsible for the high photostabilizing efficiency of I. Both compounds also inhibit the photolysis of the luminescent ,,,fl-unsaturated impurity groups present in the polymer; possible mechanisms are discussed.