Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/1999
Publication Date: N/A
Interpretive Summary: Replacement of petroleum lubricants with those produced from vegetable oils can benefit the environment, because vegetable oil-based lubricants are biodegradable. However, recent biodegradable lubricants are either too expensive or they don't perform well. One problem is that vegetable oil solidifies at higher temperatures than petroleum based lubricants. This was compared by determining pour points of a series of vegetable oils. Then the oils were blended with the synthetic biodegradable diluents which still pour at very low temperatures. However, the amounts of diluents required to eliminate the problem of the blend solidification were too high to be economically feasible. Incorporation of pour point depressants, produced from polymers, helped to some extent solving this problem. This study provides the data which allow one to determine how much improvement can be achieved by blending with the diluents and by incorporating the depressants into vegetable oils.
Technical Abstract: Low temperature properties need improvement before vegetable oils can receive wider recognition as biodegradable lubricants. Effects of dilution with major biodegradable fluids, namely polyalphaolefin (PAO2), di isodecyl adipate (DIDA) and oleates, as well as impact of pour point depressant (PPD), were investigated. Since solidification of mixed unsaturated triacylglycerols is a complex thermodynamic process, the study was limited to pour point determinations. Vegetable oils demonstrated higher pour points with increasing levels of saturation and chain length. Cis' unsaturation and hydroxy groups favored lower pour points. Dilution with oleates appeared less effective than dilution with PAO2 and DIDA. Addition of 1% PPD (w/w) depressed pour points down to -33C for canola and -27C for high oleic sunflower oil. However, neither higher amounts of PPD nor incorporation of diluent produced further depression. Pour points were not proportional to the amount of diluent and ceased with further dilution. Existing low temperature performance of vegetable oils limits their prospectives as biodegradable lubricants, but well-balanced usage of PPD and diluents can deliver some improvements.