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Volume 5, Issue 10
(November 2008)
ISSN: 1546-962X
Study on Antioxidative Synergism of Molybdenum Dialkydithiocarbamate with Alkylated Diphenylamine Antioxidants The antioxidation properties of molybdenum dialkyldithiocarbamate, p,p-dioctyldiphenylamine and mixed octylated and butylated diphenylamine additives in poly-α-olefin (PAO) lubricant or mineral oil 150 SN were evaluated by differential scanning calorimetry (DSC) and the Modified Penn State Micro-oxidation Test (PMOT). DSC test measures incipient oxidation temperature and oxidation induction time of the lubricants at high temperatures and the weight loss of oil with deposits formed are measured by the PMOT test. DSC results show that antioxidation properties and of p,p-dioctyldiphenylamine and octylated and butylated diphenylamine were improved significantly by molybdenum dialkyldithiocarbamate addition. PMOT results indicate that when it was combinied with p,p-dioctyldiphenylamine, molybdenum dialkyldithiocarbamate can also effectively reduce the increase in weight loss of oils and deposits formed in oils. These results suggest that the molybdenum dialkyldithiocarbamate shows a good antioxidative synergism with alkylated diphenylamine antioxidants. In addition, FTIR results from the PMOT test confirm that the addition of molybdenum dialkyldithiocarbamate can significantly enhance the oxidation induction time of oils containing p,p-dioctyldiphenylamine and inhibit formation of oxidation products including carbonyl bonds or hydroxyl group. ESR analysis from the PMOT test indicate that molybdenum dialkyldithiocarbamate may form stable radicals with arylamine by the coordination effect. Finally, the proposed mechanism of the inhibition involves a synergy between molybdenum dialkyldithiocarbamate and arylamine antioxidants.
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Paper ID: JAI101814 | ||
