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Evaluation of Alkali Metal Salts as Synergists for Arylamine Antioxidants in Synthetic Lubricants
ISSN: 0148-7191, e-ISSN: 2688-3627
Published October 16, 2000 by SAE International in United States
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Differential scanning calorimetry (DSC) and oxidation-corrosion tests were employed to evaluate the performances of ester lubricants containing alkali salts, e.g. lithium perfluorobutyrate, sodium stearate, sodium acetylacetonate, sodium perfluorobutyrate, sodium trifluoroacetylacetonate, potassium perfluorobutyrate, and potassium trifluoroacetylacetonate. In the isothermal and temperature programmed DSC oxidation test, alkali salts are not only good effective antioxidation synergists for arylamine compounds such as p,p′-dioctyldiphenylamine (DODPA), but also effective deposit inhibitors. When combined with arylamine antioxidants, the salts can also effectively reduce the increases in viscosity, acid number and deposit formation of the ester oils in oxidation-corrosion tests. The changes occurring to DODPA in the oxidation of esters, with and without C3F7COONa, were followed by mass (GC/MS) chromatography (MC). The proposed mechanism of the inhibition involves a synergy between alkali metal salts and arylamines. Although DODPA does not react directly with the alkali salt, the salt still functions within the antioxidation mechanism of DODPA. When DODPA reacts with free radicals to form alkyl and hydroxy substituted benzoquinonemonoimine compounds (with mass to charge ratio M/Z, 422), the alkali metal ion can participate and produce a new intermediate product having high antioxidant activity; this intermediate product serves as the main antioxidant, long after the depletion of DODPA. This process may involve a reaction between alkylphenylamino alkylphenol and the alkali metal ion. The intermediate product is believed to be the salt of alkylphenylamino alkylphenol.
CitationYao, J., "Evaluation of Alkali Metal Salts as Synergists for Arylamine Antioxidants in Synthetic Lubricants," SAE Technical Paper 2000-01-2922, 2000, https://doi.org/10.4271/2000-01-2922.
- Davis, T. G., and Thompson, J. W., “Synergistic Antioxidants for Synthetic Lubricants,” Ind. Eng. Chem. Prod. Res. Dev., 5, 1, p76 (1966).
- Chao, T. S., Hutchison, D. A., and Kjonaas, M., “Some Synergistic Antioxidants for Synthetic Lubricants,” Ind. Eng. Chem. Prod. Res. Dev., 23, 1, p21 (1984).
- Hsu, S. M., “Review of Laboratory Bench Tests in Assessing the Performance of Automotive Crankcase Oils,” Lubr. Eng., 37, 12, p722 (1981).
- Wesolowski, M., “Thermal Analysis of Petroleum Products,” Thermochimica Acta, 46, p21 (1981).
- Zeman, A., stuwe, R. and Koch, K., “The DSC Cell - A Versatile Tool to Study Thermal-Oxidative Degradation of Lubricants,” Thermochimica Acta, 80, p1 (1984).
- Zeman, A., “DSC, PDSC - Possible Use in the Assessment of the Thermal Oxidative Stability of Synthetic oils for Aircraft Turbines,” Schmiertechnik und Tribologie, 29, 2, p55 (1982).
- Branes, J. R.. and Bell, J. C., “Laboratory Screening of Engine Lubricants for High Temperature Performance,” Lubr. Eng., 45, 9, p549 (1989).
- Zhang, Y, Pei, P., Perez, J. M.and Hsu, S. M. “A New Method to Evaluate Deposit Forming Tendency of Liquid Lubricants by Differential Scanning Calorimetry,” Lubr. Eng., 48, 3. p189 (1992)
- Zhang, Y, Perez, J. M. Pei, P., and Hsu, S. M. “The Deposit Forming Tendencies of Diesel Engine Oils - Correlation Between the Two-Peak Method and Engine Tests” Lubr. Eng., 48, 3 p221 (1992)
- Yao, J. B., “Evaluation of Alkali metal salts as Deposit Inhibitors for Synthetic lubricants by Differential Scanning Calorimetry (DSC),” Thermochimica Acta, 296, p105 (1997).
- Yao, J. B. and Dong, J.X., “Evaluation of Sodium Stearate as a Synergist for Arylamine antioxidants in Synthetic lubricants,” Thermochimica Acta, 262, p157 (1995).
- Yao, J. B. and Dong, J. X., “Antioxidation Synergism between Alkali Metal Salts and Arylamine Compounds in Synthetic Lubricants,” Trib. Trans.,39, 2, p498 (1996).
- Yao, J. B. and Dong, J. X., “Evaluation of Potassium Trifluoroacetylacetonate as a Synergist for Arylamine antioxidants in Synthetic lubricants,” Synthetic Lubrication, 13, 2, p163 (1996).
- Yao, J. B, “Evaluation of Sodium Acetylacetonate as a Synergist for Arylamine antioxidants in Synthetic lubricants,” Trib. Int'l, 30, 11, p795 (1997).
- Yao, J. B, “The Role of Sodium Perfluorobutyrate in Promoting the Antioxidancy of DODPA in Synthetic Esters,” Trib. Trans.,42, 1, p84 (1999).
- Ravner, H, Moniz, W. B.and Blachly, C. H., “High Temperature Stabilization of Polyphenyl Ethers by Inorganic Salts,” ASLE Trans., 15, 1, p45 (1972).
- Ravner, H, and Kaufman, S., “High-Temperature Stabilization of Polyphenyl Ethers by Soluble Metal Organic Salts,” ASLE Trans., 18, 1, p1 (1975).
- Jensen, R. K., Korcek, S., Zinbo, M. and Gerlock, J. l., “Regeneration of Amine in Catalytic Inhibition of Oxidation,” Journal of Organic Chemistry, 60, 17, p5396 (1995).