Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 7, 2007
Publication Date: June 1, 2008
Citation: Sharma, B.K., Doll, K.M., Erhan, S.Z. 2008. Ester hydroxy derivatives of methyl oleate: tribological, oxidation and low temperature properties. Bioresource Technology. 99(15):7333-7340. Interpretive Summary: Several important properties were determined for a series of compounds that we have made from vegetable oil derived substance, methyl oleate. The compounds, which have a branched molecular structure, are potentially useful in the lubricant, fuel, and surfactant industries. The surface tension of these compounds was measured confirming the branching nature of their structures. Their potential as lubricant additives was determined by measuring the reaction of our substance with oxygen, using two different methods. We were able to determine improved stability compared to ordinary vegetable oil lubricants. Our compounds also show better friction reducing ability compared to the starting materials. This research benefits the vegetable oil industry by helping to open markets for vegetable oil derived fatty materials and industries where an environmentally friendly lubricant (such as forestry) would be ideal.
Technical Abstract: Five branched oleochemicals were prepared from commercially available methyl oleate and common organic acids and their lubricant properties were determined. These branched oleochemicals are characterized as alpha-hydroxy ester derivatives of methyl oleate. These derivatives show improved low temperature properties over olefinic oleochemicals by pour point and cloud point measurements. The derivatization also increased thermo-oxidative stability, measured using both Pressurized Differential Scanning Calorimetry (PDSC) and Thin Film Micro Oxidation (TFMO). Tribological behaviors were evaluated as additives in soybean oil and polyalphaolefin using four-ball and ball-on-disk configurations. These derivatives have good anti-wear and friction-reducing properties at relatively low concentrations under all test loads. Their surface tensions were determined and a trend of larger branches causing lower surface tension was also observed, except in the case where the carbonyl containing levulinic acid was used. It had a higher surface tension. Overall, the data indicate that some of these derivatives have significant potential to be used as a lubricating oil or fuel additive.