Synthesized biolubricants from naturally derived oleic acid: oxidative stability and cold flow performance

Authors: Sarker, Majher; MAINALI, KALIDAS - Oak Ridge Institute For Science And Education (ORISE); Sharma, Brajendra - Bk; Yadav, Madhav; Ngo, Helen; Ashby, Richard - Rick

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2023
Publication Date: 8/26/2023
Citation: Sarker, M.I., Mainali, K., Sharma, B.K., Yadav, M.P., Lew, H.N., Ashby, R.D. 2023. Synthesized biolubricants from naturally derived oleic acid: Oxidative stability and cold flow performance. Industrial Crops and Products. https://doi.org/10.1016/j.indcrop.2023.117315.
DOI: https://doi.org/10.1016/j.indcrop.2023.117315

Interpretive Summary: Conventional petroleum lubricants are widely used in industrial equipment. Unfortunately, the excessive use of these petroleum-based products can quickly enter the environment, which leads to severe water and soil contamination. In this study, naturally derived fatty acids have been used to synthesize five triesters for potential use as biolubricants. The thermal and kinetic properties of the triesters are evaluated to determine their storage stability and reusability. According to the thermogravimetric analysis and differential scanning calorimetry results, the synthesized biolubricants have excellent thermal stability and superior cold flow properties. Overall, these studies confirmed that the biolubricants produced using naturally saturated or monounsaturated fatty acid can potentially replace the harmful petroleum lubricants.

Technical Abstract: This research demonstrates the evaluation and comparison of thermal and kinetic properties of bio-lubricants synthesized from naturally derived fatty acids. The oxidative stability of the vegetable oil-based bio-lubricants affects their storage stability and reusability. Five different types of bio-lubricants have been synthesized from oleic acid, iso-oleic acid and iso-stearic acid. The thermogravimetric analysis is conducted in the presence of air and nitrogen. Comparative studies of the kinetic parameters of each synthesized product show that these biolubricants are thermally stable. The calculated activation energy shows that trimethylolpropane iso-oleic acid ester (TMP-IOA) is thermally stable with (Ea)=188.37 kJ/mol. In the oxidative environment, trimethylolpropane iso-stearic acid (TMP-ISA) ester is found as the most stable bio-lubricant with average activation energy (Ea)= 109.8 kJ/mol. The glyceride-iso-oleic acid (GLY-IOA) shows a high range frequency factor indicating complex behavior in an air environment. Among these lubricants, the GLY-IOA exhibits superior cold flow properties as measured using cryogenic differential scanning calorimetry. Overall, these comparative studies confirm that the lubricant base oils produced using saturated or monounsaturated fatty acid provide a good combination of thermal and oxidative stability along with cold flow properties.