Effect of ultrasonication on lubrication performance of cellulose nano-crystalline (CNC) suspensions as green lubricants.

Industrial lubricants are widely introduced to the mechanical systems to reduce the wear and energy losses. With the increasing demand for environmental protection, developing eco-friendly lubricants becomes more crucial. Due to their abundance, biodegradability, non-toxicity, high thermal stability and low cost, cellulose nanocrystals (CNCs) may be an appropriate choice for formulating green lubricants. In this study, using different microstructural and tribological characterization methods, we systematically investigated the effect of ultrasonic treatment on lubrication performance of CNC aqueous suspensions. It was observed that within sonication energy of 4-50 kJ/g, there exists an optimum condition for tribological measurements. In comparison to the unsonicated suspensions, sonicated CNC lubricants could decrease COF (coefficient of friction) and wear by almost 25 and 30% respectively. Results of this study suggest that ultrasonication processing can significantly improve lubrication performance of CNC aqueous suspensions.