STUDIES ON MASTICATION STAGE BINDING OF ANTIOXIDANTS

Paraphenylenediamine and diphenylamine were chemically attached to nat ural rubber during mastication. The rubber bound antioxidants were cha racterized by TLC, H-1-NMR, IR and TGA. The efficiency and permenance of these bound antioxidants were compared with a conventional amine ty pe antioxidant in filled natural rubber vulcanizates. The rubber bound antioxidants were found to be less volatile and less extractable as c ompared to conventional antioxidants. The vulcanizates showed improved ageing resistance as compared to vulcanizates containing conventional antioxidants. This semisolid rubber bound antioxidant can reduce the amount of plasticizer required for compounding.