Hindered Phenol Antioxidants

About This Product

Polymers degrade by autoxidation: heat and shear generate alkyl radicals, oxygen converts them to peroxy radicals, those abstract hydrogen to form hydroperoxides and a further radical, and the cycle accelerates itself. The visible results are chain scission or crosslinking, yellowing, loss of impact strength and eventual embrittlement. Hindered phenols are primary antioxidants, also called radical scavengers. The phenolic hydroxyl donates its hydrogen to a peroxy radical, terminating that chain, and the resulting phenoxy radical is stabilised by the bulky groups flanking it so it does not go on to start a new one. They are almost always used with a secondary antioxidant that decomposes hydroperoxides, the two acting synergistically. Four standard grades are offered. 1010 is the high molecular weight tetrafunctional phenol used where low volatility and extraction resistance are needed. 1076 is the monofunctional octadecyl ester, more soluble and lower in cost. 1098 is the bis-amide type favoured in polyamides. 3114 is the isocyanurate type used where higher thermal stability is required. All are declared for polyolefin resins including polythene, polypropylene, polyurethane, polyformaldehyde, ABS resin, polyvinyl acetal, synthetic rubber and petroleum products.