Reaction of aromatic amines with epoxidized natural rubber latex

Since oxidizability of raw rubber is adversely affected by epoxidation, an attempt was made to bind an amine antioxidant to the rubber molecule through the oxirane group. Effective binding was observed only if the latex is neutralized before addition of the amine. Of the three amines used, 4‐amino‐para‐phenyl diamine (pAA) reacted faster than meta‐nitro‐aniline (mNA), where as N‐isopropyl‐N′‐phenyl‐para‐phenyl diamine (IPPD) was the least reactive. Crosslinking was observed with the primary amine, while, with higher epoxy contents, cyclization products were also formed. mNA had little effect on oxidation resistance once it was bound.