Submitted to: Fuel
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2001
Publication Date: N/A
Interpretive Summary: Currently lubricant manufacturers are increasingly using high saturate base oils due to their better oxidation and performance properties. This shift is primarily because of poor oxidative and disposal problems associated with high aromatic base oils. Now, the saturate molecules control most of the physical properties in these oils. Characterization methods previously developed for high aromatic base oils will be inadequate to address all the structural diversities of saturate rich base fluids. In this study, a methodology is established to understand the thermal behavior of the oils. These would be useful for the total characterization of any oil, including vegetable origin. This is more important when large scale efforts are made to produce lubricants and hydraulic fluid from vegetable oils. A good understanding of the thermal and deposit forming behavior along with other performance properties are necessary for any lubricant formulation. It has been observed that certain saturate structures can be used to correlate with physical and chemical properties of base fluids and subsequently in optimizing production of these oils in refineries. A knowledge of the thermal behavior of these oils in terms of their molecular structure would also help understand the oxidation behavior of vegetable oils and their performance in lubrication and hydraulic systems. The industry and manufacturers of vegetable oil based industrial fluids would also benefit from the structure based property and performance evaluation methodogy.
Technical Abstract: Due to the increasing demand for high saturate (Gr II and III) base oils for use in specialty lubricant application, it is necessary to obtain a clear picture of the base oil molecular distribution. These oils are more stable to oxidation and exhibit superior performance based characteristics. As the aromatic content reaches a minimum value, the saturate molecules control most of the physical properties in these oils. Molecular structure based characterization developed for conventionally refined base oils will be inadequate to address all the structural diversities of these base fluids. In this study, results from different thermal analysis methods (thin film micro oxidation (TFMO) and pressure differential scanning calorimetry (PDSC) were explained in terms of the quantitative 13C NMR (inverse gated, CSE, GASPE) data. Correlations obtained between physical properties (e.g. viscosity), oxidation (evaporation, insoluble deposit) and structural data indicate the significance of base oil saturate hydrocarbons in influencing most of the performance properties.