Use of 1H-NMR spectroscopy, diffusometry and relaxometry for the characterization of thermally-induced degradation of motor oils

We explore the capability of H-1 NMR spectroscopy, relaxation and diffusion for the characterization of thermally-induced degradation of fresh motor oils. Temperature dependent measurements of diffusion show a weak sensitivity to thermal degradation. In contrast, both the transverse relaxation at H-1 Larmor frequencies of 20 MHz and 400 MHz, as well as the longitudinal relaxation at 60 kHz showed to be sensitive to thermally-induced effects at measured temperatures within the range -10 degrees C to 30 degrees C. Results show that the highest sensitivity significance can be reached by fast field-cycling NMR relaxometry measurements at low magnetic fields.

Automated summary

This study investigates the use of H-1 NMR spectroscopy, relaxation, and diffusion for characterizing the thermally-induced degradation of fresh motor oils. The results indicate that longitudinal and transverse relaxation are more sensitive to thermal effects, especially when measured at low magnetic fields using fast field-cycling NMR relaxometry.