Thermal behavior of prospective hydroxy acid grease thickeners

Melting points and heats of fusion were determined for 13 hydroxy acids and their lithium salts with chain lengths ranging from 14 to 24 carbons. Included were hydroxy acids prepared from two unusual plant sources,Lesquerella sp. andCrambe abyssinica. Upper melting point temperatures, transition entropies, and heat capacity changes of the lithium salts on heating and cooling suggest that many of the salts, particularly those of 14-hydroxyeicosanoic and 9(10)-hydroxystearic acids, would perform satisfactorily as gelling agents in the production of lubricating greases. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned. metal salts of unsubstituted fatty acids, which also can serve as grease thickeners.