Benzofuroxans as Rubber Additives

Benzofurazan 1-oxide, commonly called benzofuroxan (BFO), was shown to decrease hysteresis of carbon black-filledrubber vulcanizates by as much as 30%. Presumably, BFO promotes increased bonding between the elastomerand carbon black resulting in reduced “Payne Effect” in the vulcanizate. BFO was added during the mixing of themasterbatch at various temperatures. It was found that high temperature mixing was necessary to achieve maximumhysteresis reduction and that more effect was noted with high surface area blacks. Nickel salts were found to modifythe reaction between BFO and the elastomer/black.