(573o) Tribological Properties of Bio-Based Lubricants Obtained from Castor Oil Fatty Acids and Isopentanol

Chemically modified vegetable oils may be used for several applications such as lubrication. Some bio-based lubricants may reduce friction and prevent direct metal-to-metal contact through a thin film, with polar groups attached to long carbon chains that enable the oil molecules to cling to metal surfaces while sliding over themselves. In this study, a bio-based lubricant synthesized from castor oil using isopentanol was evaluated for thermal stability and tribological properties. The bio-lubricant sample was obtained from an esterification reaction between Castor oil fatty acids and isopentanol, followed by epoxidation and epoxide ring-opening reactions using the same alcohol as the nucleophilic agent. A Thermal Gravimetric Analyzer (TGA) Model DTG-60 (Shimadzu, Japan) was used to monitor the weight changes of the samples, while the derivative of a TG curve (DTG) evaluated the rate of weight loss during heating versus temperature, from 30 °C to 700 °C at a constant heating rate of 10 °C/min. For tribological behavior, four-ball experiments were carried out using a DHR-3 rheometer (TA Instruments, New Castle, USA), with experimental conditions modified from the ASTM D4172 method within the limits of the rheometer. The tribological tests were conducted at a sliding velocity of 0.46 m/s, a temperature of 75 °C, a load force of 55 N and for 1 h (Figure 2). The balls are made of a chrome steel alloy (AISI52100, 64 HRC), with diameter of 12.7 mm and surface roughness of 0.015 μm. An optical microscope (Zeiss, Germany) with 100× zoom was used to study the morphology and measure the wear scar diameter (WSD). Samples of Castor oil fatty acids and Mineral Oil were used as reference for tribological comparisons with our synthesized sample.