A Co‐Vulcanizable Antioxidant for Enhanced Migration Resistance in Diene Rubbers Based on Acrylation

ABSTRACT p ‐Phenylenediamine (PPD) antioxidants play a vital role in protecting diene rubbers from oxidative degradation. However, their strong polarity often leads to migration from the bulk to the surface, adversely affecting product appearance and reducing long‐term anti‐aging performance, which limits their wider use. To address this, a novel antioxidant, EMA 2 ‐PPDA (designated E 2 P), was synthesized by attaching two 3,4‐epoxycyclohexylmethyl acrylate (EMA) units to an N‐phenyl‐ p ‐phenylenediamine (PPDA) core via an epoxy‐amine reaction. E 2 P exhibits a notable capacity to react during vulcanization. This characteristic can improve its retention within diene rubber matrices, making it less prone to migration compared to the conventional antioxidant 6PPD (N‐(1,3‐dimethylbutyl)‐N'‐phenyl‐p‐phenylenediamine). Results show that E 2 P provides excellent anti‐aging protection in both natural rubber (NR) and butadiene rubber (BR), with the best overall thermal‐oxidative stability observed at 3 phr (parts per hundred rubber). In addition, E 2 P exhibits a markedly improved resistance to migration compared to 6PPD under the investigated conditions. These findings indicate that introducing acrylate groups represents a promising strategy for improving the migration resistance of PPD‐type antioxidants in vulcanizates, without compromising their antioxidative activity.