NMR relaxometry analysis of molecular degradation in internal combustion engine lubricants

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

MAGNETIC RESONANCE IN CHEMISTRY

JOHN WILEY & SONS LTD

Año: 2020 p. 1 - 7

0749-1581

A set of experimental techniques headed by proton fast field-cycling nuclearmagnetic resonance (1HFFC-NMR) were used to analyze the effects ofdegradation of lubricant oil used in an internal combustion engine (ICE). Itsrelaxometric, spectroscopic, and rheological properties were evaluated andinterpreted in terms of changes in the chemical structure and the involvedmolecular dynamics. In order to better understand the relaxometric behavior,chemical changes induced by heat were investigated for selected n-alkanes, asmodel-systems due to their structural simplicity. Fourier transform infrared(FTIR) spectroscopy, viscosity measurements, and foaming were used tocontrast NMR relaxometry experiments. Main observed changes associatedwith oil degradation can be attributed to molecular oxidation, fragmentation,and ramification. As an outstanding feature of this work, we show that therelaxometric analysis can be done without any special treatment of the sample,allowing results in less than 10 min.