"ntiozonant activity of the joint application, said antiozonants being represented by latter, the higher molecular weight notwithstanding. the formula R-NA-R-NBR, in which R is a As mentioned under methods of test, data for static member of the group comprising p,pbiphenylene, p,p' ozone tests and for outdoor weathering tests coniirm the methylenediphenylene, and p,piminodiphenylene, and dynamic te" . . . .