Photo-antioxidants testing

From these data, the conclusion could be drawn that the surface chemistry plays a role in the discoloration mechanism of tested system. The surface chemistry must be involved in the partial oxidation of the antioxidant material presumably by the photo-generation of radicals from the Ti02 crystal but, the data do not suggest clues about the role of the ammonia, nature of the phenol moiety and/or surface adsorption. 

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