Process Temperature Profile and Rheological Properties of Greases from Vegetable Oils

Abstract

Greases are composed by lubricating oil dispersed in a thickener that can be a metal soap, polymers or clays. Grease production using vegetable oils is increasing due to biodegradability requirements. Since vegetable oils present a worse oxidation and hydrolysis stability than mineral oils, it is usually difficult to produce a neutral grease using them. Four greases were produced using soybean oil as lubricating oil and lithium 12-hydroxy-stearate as thickener. The maximum temperature of reaction was ranged from 230˚C to 120˚C in a bench process and a reduction in the final product acidity was observed (from 8.2% acid to 0.05% alkaline). Traditional tests to evaluate thickener structure resistance like 10,000-time worked penetration, roll stability and dropping point were performed and results compared. In addition, rheological tests were performed and the results were also compared.