FIELD-CYCLING NMR RELAXOMETRY ANALYTICS OF A LUBRICANT BASE OIL SUBJECTED TO THERMAL STRESS

EUSTAQUIO M. ERRO; CARLA C. FRAENZA; LEANDRO J. GERBINO; ESTEBAN ANOARDO

Pisa

Conferencia; 11th Conference on Fast Field Cycling NMR Relaxometry; 2019

University of Pisa and ICCOM-CNR.

Lubricant oils are complex mixtures of hydrocarbons composed of a base oil and additives [1]. They are indispensable in most of the mechanical systems that involves mobile parts, and it is expected that their performance results progressively affected as a consequence of fulfilling its functions [2]. A variety of physical and chemical factors affect the lubricant at molecular level. Heating is present in all internal combustion engines, and has an active role in processes as, nitrogen, oxygen and sulfur incorporation, hydrocarbon chains ruptures and ramifications [3-7].Proton fast field-cycling nuclear magnetic resonance (H1 FFC-NMR) relaxometry can be used to study the effect of thermal stress in a lubricant base oil. In a recent paper, we show results of base oil that underwent controlled thermal degradation [8]. The relaxometric response was evaluated and interpreted in terms of self-diffusion and molecular rotations. Base oil degradation was done at T=90°C and T=270°C, and the produced degradation becomes clearly evidenced in the profiles, especially at low relaxation fields.In this work we show new results and other experiments using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMRS) that support the changes observed in the relaxation dispersions curves. Oxidation, hydrocarbon chains ruptures and ramification promoted by heating were clearly evidenced. References[1] Meyers R. A., Handbook of petroleum refining processes (New York, N.Y. McGraw-Hill Professional, 2004).[2] Ballari M., Bonetto F., Anoardo E., J. Phys. D: Appl. Phys. 2005, 38, 3746-3750.[3] Al-Ghouti M. A., Al-Atoum L., J Environ Manage. 2009, 90, 187-95.[4] Wang S. S., Lee S. H., Smolenski D. J., Sensors Actuators B. 1994, 17, 179.[5] Igarashi J., Japan. J. Tribol. 1990, 35, 1095.[6] Fox M. F., Picken D. J., Symons M. C. R., Thomson A. L., Tribol. Int. 1997, 30, 417.[7] Mortier R. M., Orszulik S. T., Chemistry and Technology of Lubricants (Suffolk, UK: Edmundsbury, 1997) pp 98?144.[8] Erro E. M., Fraenza C. C., Gerbino L. and Anoardo E., Mol. Phys. 2018, 116, 983-989.