Mechanisms of antioxidant action: Mechanochemically bound antioxidants to polyethylene and polypropylene

It is shown that a thiolamide antioxidant, 4-mercaptoacetamido diphenylamine (MADA) can be reacted with both polypropylene and polyethylene in a mechanochemical process. The resulting bound antioxidant concentrates (MADA-B) can be used for the thermal and photostabilisation of the parent polymers. The adduct is very stable to solvent extraction and is also very effective as a high temperature antioxidant for polypropylene subjected to water leaching.The uv stabilising mechanism of MADA-B is believed to be related to the regenerative process involved in the mechanism of stabilisation by hindered nitroxyl radicals.