Synthesis and Lubricant Properties of Estolides based on Fatty Acid

Enhancing the value of fine chemicals based on biomass resources is an important objective foraddressing environmental and other concerns such as demand for renewable or green products, as well as fromthe political perspective to reduce dependence on fossil feedstock associated with the use of petroleum-basedproducts. Based on these considerations, we studied the synthesis of estolide using waste plant-based oil mate-rials and their application as lubricants and pour point depressants. Five estolides were prepared by varying molarratio of palmitic acid (PA) to oleic acid (OA) using a reaction time of 48 h. The estolides were characterized bysize exclusion chromatography (SEC) and nuclear magnetic resonance (NMR). The isolated yields were in therange of 57-78 % and purity was 93-97%, showing iodine values of 18.2-37.8, total acid numbers (TANs) of75.6-94.2 mg KOH/g and estolide numbers (ENs) of 1.2-1.8. Increasing the ratio of OA to PA in the synthesisdecreased the kinematic viscosity and clouding point of the estolides. Four ball wear test of the estolides as abase oil demonstrated that the wear scar diameter (WSD) of the estolides was significantly lower (0.320-0.495mm) than the WSD of general base oils such as 150N and Yubase (0.735 and 0.810 mm, respectively), indicatingbetter wear resistance of the estolides. However, the lubricant property was found to be independent of the amountof OA in the estolides. These new materials are prospective candidates for application as a lubricant base oil.Keywords: estolides (에스토라이드), fatty acid (지방산), lubricants (윤활제), wear scar diameter (마모흔 직경)