Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/7/2004
Publication Date: 3/10/2005
Citation: Sharma, B.K., Adhvaryu, A., Perez, J.M., Erhan, S.Z. 2005. Soybean oil based greases: influence of composition on thermo-oxidative and tribochemical behavior. Journal of Agricultural and Food Chemistry. 53(8):2961-2968. Interpretive Summary: Greases in general are thickeners (metal soap) dispersed in base oils. The biodegradable properties and lubricity of greases depend on both the base oil and the thickener. Mineral oils are the most widely used base fluids due to their low cost, but recent environmental awareness has forced us to consider the use of vegetable oils in grease preparations. Vegetable oils have advantages because they are a naturally renewable resource, environmentally safe, and they have good lubricity and viscosity-temperature characteristics. This study presents the data on thermal and oxidation stability and friction-wear characteristics of biodegradable greases formulated with soybean oil and different compositions of metal soap thickener. It has been found that changing the thickener to base oil ratio; fatty acid chain length; unsaturation and additive concentration; bring improvements in thermo-oxidation and friction-wear properties of vegetable oil-based greases. These basic studies will enable us to develop soybean oil-based grease for use in applications, where lubricants are lost to the environment. Farmers would also benefit as new markets are created for soybean oils.
Technical Abstract: The biodegradable properties and lubricating ability of greases depend on both the base oil and the thickener. Mineral oils are the most widely used lubricant base fluids due to their inherent lubricity and low cost, but recent environmental awareness has forced to consider the use of biodegradable fluids such as vegetable base oils and certain synthetic fluids in grease formulations. This study presents the data on thermo-oxidation behavior and tribology of biodegradable greases formulated with soybean oil and different compositions of metal soap thickener. The composition of thickener has been varied by using fatty acids (FA) with different degrees of unsaturation, FA of different chain lengths, and different metal:FA ratios. The improvement of thermo-oxidation and tribological properties as a result of changing thickener:base oil ratio and antioxidative effect of some suitable additives have also been evaluated.