Vegetable oil-based ethanolamides as potential anti-oxidant additives for lubricant formulations

Abstract

Novel antioxidant mono- and diethanolamide, eight additives have been prepared from castor oil, coconut oil, thumba oil and sal fat. These have been evaluated for antioxidant efficacy taking epoxy karanja oil as base oil at 0.5-5% concentration. Antioxidant tests have been performed on Rotating Pressure Vessel Oxidation Test RPVOT and Differential Scanning Calorimetry DSC. Among the prepared mono and diethanolamides, only diethanolamide-based additives have exhibited potential anti-oxidant behavior. Coconut diethanolamides containing saturated medium chain fatty acids have exhibited excellent stabilities, followed by diethanolamides of sal rich containing saturated long chain fatty acids. The castor based diethanolamides, which are rich in mono unsaturated hydroxy fatty acid show slightly lower stabilities, while thumba with polyunsaturation exhibits poor oxidation stabilities. Both the methods have shown that the fatty diethanolamides exhibit extraordinary stabilities compared to commercial antioxidant, butylated hydroxy toluene BHT at 1-5% concentration. The study indicates that the presence of saturation and medium chain fatty acids in the diethanolamide-based additives improves the oxidation stability of the base oils.