MECHANISMS OF ANTIOZONANT PROTECTION - UNEXTRACTABLE NITROGEN IN AGED CIS-POLYBUTADIENE VULCANIZATES

Rubber (BR) vulcanizates contaning DOPPD antiozonant and DPG accelerator have been aged under various conditions, and the soluble constituents have been removed by acetone extraction. Small amounts of nitrogen become bound to the rubber network as a result of side reactions associated with vulcanization. Additional nitrogen becomes bound to the rubber during aging. The bound nitrogen level is greater in (a) dynamic as compared to static testing, and (b) an ozone atmosphere as compared to air or nitrogen. The authors believe that the principal reason for nitrogen becoming bound during aging is the trapping of macroalkyl radicals by aromatic amine-derived species (e. g. , nitrones).