Formation and analysis of particulate carbon in a synthetic lubricant

R. Sabia, K. Powers, J. H. Adair

Research output: Contribution to journalArticlepeer-review


The formation of discrete carbonaceous particles has been investigated for a conventional synthetic ester-based lubricant degraded in thermal and thermal oxidative environments. Experimental factors included oxidative and nonoxidative environments, high and low humidities, and the presence or lack of a metal catalyst surface, with all samples generated at 250 °C. Characterization performed for changes in antioxidant content, IR spectroscopy, molecular weight, total acid number, viscosity, and uv/vis absorbance spectrometry were used to determine the influences of the aforementioned variables on the rates of oil degradation and formation of high-molecular-weight species. Discrete carbonaceous particle formation was analyzed using Einstein's relationship for the viscoelastic behavior of particles in Newtonian fluids and by calculating associated radii of gyration. This viscoelastic behavior of the particles in solution is used to demonstrate how the absorption behavior of the carbonaceous degradation products tracks the discrete particulate species. The results show the formation of particulate species to be diffusion-limited after antioxidant depletion, and optical absorption analysis is shown to be a viable technique for monitoring the formation of discrete carbonaceous particles during lubricant degradation.

Original languageEnglish (US)
Pages (from-to)954-963
Number of pages10
JournalColloid and Polymer Science
Issue number10
StatePublished - 2000

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Colloid and Surface Chemistry
  • Materials Chemistry


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