Eco-friendly Lubricating Oil: Effects of Functional Groups in Methyl Oleate and Olive Oil on Lubrication.

Abstract

The lubrication characteristics of the olive oils, which are used as biodegradable lubricants, on the steel ball were examined on the viewpoint of their growing area and quality of the olive oil. The discoloration of virgin olive oil and the friction face and/or the friction force of the steel ball were found to be dependent on their growing area as well as pure olive oil.Property of the constituent metal constituents of steel ball on the air oxidation of methyl ester of oleic acid, which is major constituent fatty acid of olive oil and the lubrication characteristics of the resulting oxidation products, were investigated. The autoxidation of methyl oleate under the existence of each acetylacetonatos of Cr, Mn, Fe, Ni, Cu, and V was carried out by blowing dry air at 80̮. All the metal salts except V facilitated the oxidation. The metals employed a#ect the yields and the types of the products, i.e., hydroperoxide, hydroxide and epoxide whom the functional group exists for the center location of molecular chain.Friction test for ball bearing was conducted by using each oxidation product and parent methyl oleate. The surface of the steel ball was the abrasive wear condition by hydroperoxide. The hydroxide gave excellent lubrication characteristics by hydroxy group adsorbed on the surface of steel ball. Epoxide increased the coe$cient of friction. Methyl linoleate, having two double bonds, provided the flatted frictional surface at the ball bearing, but it is easy to be oxidized.To sum up the major characteristics of the autoxidation products which a#ect friction surface of steel ball, the function groups of center position in molecular chain of methyl oleate are of most significance. It was found that double bond and hydroxyl function of a-position of double bond are e#ective under the boundary lubrication.