Abstract
The commercial sulfur containing antioxidant AO2 (Irganox 1520) is compared with other classical phenolic antioxidants, and its special autosynergistic profile, particularly under dynamic test conditions (Brabender, 160 °C), in commercial polybutadiene rubber is investigated. AO2 outperforms all other tested phenolic stabilizers. A tentative mechanistic explanation for the action of AO2 is given, consisting of either a concerted reaction or a ‘tandem reaction’ of the antioxidant with macroalkylperoxy radicals. Other mechanistic pathways, for instance the role of the phenoxy radical 8 or its C,Orecombination products with oxygen centered radicals (such as macroalkylperoxy radicals) and of the recently synthesized stable quinone methide 10 are discussed. CIDNP experiments, generating the radical 8 from AO2, demonstrate that the main reaction between phenoxy radicals 8 is regioselective C,O-recombination, giving rise to the dimers 9a and 9b and no direct formation of quinone methide 10 and C,C-coupling products is observed.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call