Dispersion Stability and Viscosity Analysis of Palm Oil-Based Trimethylolpropane Ester with Tempo-Oxidized Bacterial Nanocellulose as Additives

Commercial lubricants currently used in automotive engines and industry are mainly based on mineral oil, which is non-renewable, non-biodegradable, and non-environmentally friendly. Moreover, conventional additives mixed in commercial lubricants contain hazardous compounds to the environment, such as zinc ash and phosphorus. Therefore, the attention to developing bio-based lubricants with environmentally friendly additives is increased. This work chemically modified palm oil methyl ester (PME) by a transesterification process using trimethylolpropane (TMP) as a reactant. To improve the physio-chemical properties of biolubricants, TEMPO-oxidized bacterial cellulose (BC) nanofibers were added to PME/TMP polyester and sorbitan monostearate (Span 60) as a surfactant. Suspensions were agitated using a hot plate magnetic stirrer and then homogenized using a high-speed homogenizer and ultrasonication probe. The dispersion stability of bio-based nanolubricants was evaluated through sediment photograph capturing. Among the various approaches available, combining chemical modification of palm oil, additives and surfactant composition, agitation, and sonication time offers the best option for better dispersion stability and improving the viscosity of palm oil-based biolubricants.