BENZOFUROXANS AS RUBBER ADDITIVES

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