Comparative Investigation of Lubricant Properties of Pongamia and Castor Oil Bio Lubricant Blended with (SAE20W40) Mineral Oil

The present work deals with the comparative evaluation of physicochemical, rheological FTIR and tribological properties between pongamia and castor oil blended with SAE20W40 by varying their proportions ranging from 10-30% (by volume) as bio-lubricant. Among all the blends, the flash point and pour point of castor blend S4 were found to be 281°C and -19°C which can be comparable to SAE20W40. The viscosity at 40°C and 100°C and viscosity index of castor blends were approximately 100 mm2/s, 14 mm2/s and 145 respectively. FTIR analysis also confirms the presence of vital carbonyl ester functional group in castor blends with oxidation onset temperature of 243°C. The tribological studies that were carried out using pin on disc tribometer as per ASTM G99-95a standards also showed that blend S4 had coefficient of friction 0.056 at higher load which was comparable to SAE20W40. Although all the blends had low oxidation stability temperature, yet castor blend S4 showed equivalent properties with commercial lubricant SAE20W40. This confirmed its suitability as a bio-lubricant base stock, supported by its physiochemical, rheological, FTIR, tribological properties.