Abstract:
Bio-lubricants are prospective substitutes for the conventional mineral oil based lubricants because they provide good lubricating properties as mineral oils with the characteristics of being renewable, biodegradable and non-toxic. Reports indicate that global market value of bio-lubricants was nearly USD 2.01 billion in 2016 and is expected to reach USD 2.64 billion by 2020. Altering regulations of lubricant industry towards the bio lubricants makes it an industry with high future growth prospects. Generally, bio lubricants are made from vegetable oils. Triglycerides are major components in vegetable oils, in which glycerol molecules with three long-chain fatty acids attached at the hydroxyl group via ester linkages. Triglyceride structure gives good qualities for boundary lubrication. Their long polar fatty acid chains interact strongly to metallic surfaces providing high strength lubricant films. The long hydrocarbon chain is oriented away from the metal surface to form a monomolecular layer reducing both friction and wear. This paper discusses the evaluation of lubricating properties of Refined, Bleached and Deodorized (RBD) Palm Oil (PO) and White Coconut Oil (WCO) with three commercial lubricating oils (SAE40, SAE30 and Hydraulic68). Kinematic viscosity, viscosity index, flash point, pour point, total acid number, copper corrosion and demulsibility of the samples were measured. Both PO and WCO were identified as good candidates to improve, but PO showed better properties compared with WCO. PO has high kinematic viscosity (@40oC=38.88cSt, @100oC=9.99cSt), high viscosity index (259) and high flash point (305oC). However, both PO and WCO showed low kinematic viscosity than commercial oils therefore suitable modification is recommended specially at low temperatures. Pour point of PO (6oC) and WCO (24oC) was considerably higher than commercial oils. Therefore, both oils, especially WCO, pour point should be adjusted using suitable additives to enable it to be used as a lubricant. Overall PO showed better performance than WCO as a lubricating oil, which is a worthy substitute for commercial oils.
