The Development of a Fully Renewable Lubricant: The Effect of Ethyl Cellulose on the Properties of a Polyhydroxyalkanoate (P34HB)-Based Grease

Abstract

In the context of the ongoing evolution of the global economy and increasing environmental awareness, green sustainable development has emerged as a crucial pathway for future advancements in the lubrication industry. In this study, we prepared bio-based greases by employing a thickener system consisting of polyhydroxyalkanoate (P34HB) and ethyl cellulose, with castor oil serving as a base oil. The results indicate that ethyl cellulose significantly and effectively enhances the grease system’s mechanical and colloidal stability. Notably, the addition of 5 wt% ethyl cellulose leads to superior mechanical and colloidal stability, while increasing concentrations gradually result in rheological properties similar to those of oleogels. Furthermore, the wear volume of grease containing 5 wt% ethyl cellulose was reduced by 39.20% compared to that of a reference P34HB grease, demonstrating its exceptional wear resistance. The present study provides a theoretical foundation and empirical evidence for the future development of biodegradable greases as substitutes for non-degradable materials, thereby expanding the range of environmentally friendly greases formulated with biomass-based thickeners.