Abstract 1‐Acryloyl‐4‐acryloyloxy‐2,2,6,6‐tetramethylpiperidine (AATP) has been covalently attached to polypropylene under conditions of reactive processing to give substantial concentrations of essentially 100% grafted antioxidant (AATP‐B). Solution of the concentrates showed that at high concentration of grafted antioxidant some homopolymerized AATP was present and the polymer undergoes transient cross‐linking during processing. Concentrates of bound AATP (AATB‐B) when used as conventional additives for polypropylene are very effective photoantioxidants due to conversion to the related polymer‐bound nitroxyl radicals by photosensitized oxidation. A typical commercial hindered phenol, Irganox 1076, when used at low concentration in combination with ‐B also acts as a photosensitizer for nitroxyl formation. Unlike low molar mass‐hindered piperidinoxyl, polymer‐bound nitroxyls are effective thermal antioxidants that synergize very effectively with low concentrations of Irganox 1076.
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Al‐Malaika et al. (1992) studied this question.