Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2003
Publication Date: 8/10/2003
Citation: CERMAK, S.C., ISBELL, T. SYNTHESIS AND PHYSICAL PROPERTIES OF COST EFFECTIVE FUNCTIONAL FLUIDS. INDUSTRIAL CROPS AND PRODUCTS. 2003. V. 18. P. 183-196. Interpretive Summary: During the winter months in the Northern United States the temperatures can reach well below the freezing point. What sort of products does your vehicle use to keep the engine and components running smoothly? Right now they're probably petroleum-based lubricants and fluids, i.e. oil and power steering fluid, along with additive packages which help make the petroleum-based products work better. The current petroleum products on the market often fail to perform in cold weather which causes unnecessary wear on your automobile. Thus there is a serious need for cost-effective, vegetable-based lubricants and fluids that have excellent low temperature properties without the addition of toxic additive packages. Our lab is working to create these new cost-effective vegetable-based lubricants and fluids from estolides which are easier on plants and animals than petroleum products. We mainly use oleic acid, an oil like cooking oil from sunflower seeds, and coconut acids, which is found in tanning oils, to make estolides. Estolides are therefore a renewable U.S.-based crop oil that will help ease the dependence on foreign, petroleum-based oils.
Technical Abstract: Biodegradable, vegetable oil-based lubricants must have better low temperature properties as well as comparable cost to petroleum oil before they can become widely acceptable in the marketplace. The low temperature property usually measured is the material's pour point, the minimum temperature at which the material will still pour. Viscosity and viscosity index also provide information about a fluid's properties where a high viscosity index denotes that a fluid has little viscosity change over a wide temperature range. Oleic acid and lauric acid were treated with varying equivalents of perchloric acid at 60oC to produce complex estolides. Yields ranged between 45-75% after purification by Kugelrohr distillation. The estolide number (EN), the average number of fatty acid units added to a base fatty acid, varied with reaction conditions. The saturate-capped, oleic estolides were esterified with 2-ethylhexanol to obtain high yields of the corresponding ester. Coconut-oleic 2-ethylhexyl estolide esters were produced by varying the ratio of oleic and coconut fatty acids with 0.05 equivalents of HClO4 to resulting in estolides with excellent cold temperature properties. The amount of oligomerization (EN) played an important role on viscosity; viscosity increased with higher oligomerization. The free acid estolides were generally several hundred centistokes (cSt) more viscous than their corresponding esters. The viscosity index ranged from 141 to 170 for the free acid estolides while the complex estolide 2-ethylhexyl esters had slightly higher viscosity indices which ranged from 159-232. These new coco-oleic estolide esters have displayed far superior low temperature properties (-36oC), were of reasonable cost, and were more suitable as a base stock for biodegradable lubricants and functional fluids than current commercial materials.