Composite of Carboxymethyl Cellulose/MXene and Span 60 as Additives to Enhance Tribological Properties of Bio-Lubricants

Bio-lubricants are the future of lubricants as a substitute for mineral lubricants; however, bio-lubricants have drawbacks, such as poor thermal-oxidative stability. In addition, during the friction process, the temperature of the lubricant increases, so the lubricant must have good thermal conductivity to conduct heat to the environment. To combat the drawbacks of bio-lubricants, some additives have been used to improve their performance as lubricants. Composites of carboxymethyl cellulose (CMC)/MXene and Span 60 as surfactants were used as additives in CPO with different compositions. The physicochemical properties of the addition of CMC/MXene and Span 60 in CPO have changed, including kinematic viscosity, TAN, thermal conductivity, and fatty acids, which have a positive impact on lubrication performance in terms of reducing oxidation processes and increasing thermal conductivity. From fatty acid composition tests and FTIR analysis, the additives work to suppress the oxidation process. A pin-on-disk test was performed to evaluate the tribological performances of bio-lubricants. The results show that CM 10 SP (0.5% wt of CMC and MXene and 1% wt Span 60) demonstrated a significant decrease in CoF and wear rate by 49% and 74%, respectively, at a load of 50 N and a speed of 1400 rpm compared to CPO without additives. An interface layer of CMC/MXene and Span 60, separating two surfaces, could induce wear on the surface of the disk and pin.