Antioxidant activity of three substituted hindered phenolic antioxidants is studied in bulk oil oxidation and thin film oxidation conditions. Test conditions of The Institute of Petroleum test method IP-48 are used for evaluation of inhibition activity of antioxidants in bulk oil oxidation regime and Pressure Differential Scanning Calorimetry (PDSC) is used for thin film oxidation regime. Para position of phenolic antioxidant has a substitution of alkyl, ester and thioether linkage in these selected antioxidants. Antioxidant activity of thioether substitution is found better that ester and alkyl substitution. Ester substitution in para position has better inhibition activity than alkyl substitution. Relative Inhibition activity of selected antioxidants is similar in both bulk oil oxidation process (which is slower oxidation reaction) and in thin film oxidation (which is relatively faster oxidation reaction.)

No abstract