Formulation of a novel biolubricant with enhanced properties using esterified rubber seed oil as a base stock

Abstract

Biolubricants, though an answer to depleting mineral oil reserves and toxic pollutants seeping into the environment, have several drawbacks. They have a limited range of viscosities, poor low temperature properties, and reduced oxidative stability. Rubber seed oil, a nonedible oil extracted from rubber (Hevea brasiliensis Muell. Arg) seeds, has been observed to serve as a good base stock for developing a novel biolubricant. This study aims at improving the properties of rubber seed oil, namely, its free fatty acid content, viscosity, cloud and pour point, tribological properties, and oxidative stability using suitable natural and synthetic additives to make it as good as commercial lubricants available in the market. A final formulation containing esterified rubber seed oil with (1% low-density polyethylene + 1.5% polypropylene as viscosity enhancers, 1.5% agarose to improve coefficient of friction, 1.5% butylated hydroxyl toluene as pour point depressant and (1% butylated hydroxyl anisole + 1.5% α-tocopherol + 1% ascorbic acid) as antioxidants has been found to have superior lubricant properties when compared to plain rubber seed oil. The biodegradability of the final formulated oil has also been studied.