Enhancing physicochemical properties of coconut oil for the application of engine lubrication

Hettiarachchi, Sunil Jayantha; Kellici, Suela; Kershaw, Matthew and Bowen, James (2023). Enhancing physicochemical properties of coconut oil for the application of engine lubrication. Tribology International, 190, article no. 109060.

DOI: https://doi.org/10.1016/j.triboint.2023.109060

Abstract

Engine lubricants require specific physical and chemical properties to function effectively and extend the lifespan of engines. Coconut oil (CCO) is an abundant, renewable, and environmentally friendly bio-based stock that has the potential to be a viable alternative to conventional mineral oil-based lubricants. In this study, we investigated the potential of CCO as a lubricant and formulated different blends with additives to enhance its physicochemical characteristics. Polymethylmethacrylate (PMMA), styrenated phenol (SP) and potassium hydroxide (KOH) were used as additives in varying concentrations. We evaluated the formulations for low pour point (PP), high viscosity index (VI) and total base number (TBN) using differential scanning calorimetry (DSC), viscometry, and titration methods (following ASTM D2270 and ASTM D2896–21 respectively). The formulated CCO was also tested for thermal, oxidative, and shear stability using thermogravimetric analysis and rheometry. The optimal formulation exhibited a PP reduction from 21^◦C to 6^◦C, improved VI from 169 to 206, and a TBN adjustment from 0 to 4.14 mg KOH g^-1. The formulated CCO also exhibited superior thermal, oxidative, and shear stability compared to unformulated CCO and reference oil (15W40). Our results suggest that blending CCO with additives can effectively enhance its suitability for engine lubrication, opening up new possibilities for environmentally sustainable and renewable lubricants.