Investigating the impact of a newly developed chemical modification technique on improving the tribological properties of high oleic soybean oil

Authors: BHOWMIK, PIASH - University Of North Dakota; Sharma, Brajendra - Bk; Sarker, Majher; CHOI, HYUNSUK - University Of North Dakota; TANG, CLEMENT - University Of North Dakota; ROY, SOUGATA - Iowa State University

Submitted to: Sustainable Energy & Fuels
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2024
Publication Date: 2/5/2024
Citation: Bhowmik, P., Sharma, B.K., Sarker, M.I., Choi, H., Tang, C., Roy, S. 2024. Investigating the impact of a newly developed chemical modification technique on improving the tribological properties of high oleic soybean oil. Sustainable Energy and Fuels. 8:1314-1328. https://doi.org/10.1039/d3se01526b.
DOI: https://doi.org/10.1039/d3se01526b

Interpretive Summary: Soybean oil has been studied as lubricating oil for various end-use applications in the automotive and industrial sectors, due to its renewability, biodegradability, and non-toxicity. A vast majority of fatty acids in regular soybean oils are polyunsaturated, which results in poor oxidative stability. High oleic soybean oil (HOSO) mostly has fatty acids with one double bond and is oxidatively stable, but still needs improvement in fraction wear and low-temperature flow properties. This research describes a novel chemical modification process to attach a branching onto unsaturated fatty acids of HOSO, which improves the low-temperature flow properties and friction wear properties. The product formation is confirmed using various analytical techniques. This work has the potential to be applied to waste cooking oil, increase their economic value, and the utilization of vegetable oils, thereby increasing the demand for farm products.

Technical Abstract: Soybean oil is currently being studied as lubricating oil in various industries, including automotive, aerospace, and UAV applications, due to its renewability, biodegradability, and non-toxicity. In vegetable oils, the vast majority of fatty acids are unsaturated. This research demonstrates that the tribological properties of high oleic soybean oil (HOSO) can be improved by the conversion of the unsaturated fatty acids to saturated fatty acids via a novel chemical modification process. Gas Chromatography-Mass Spectrometry (GCMS), 1-D Nuclear Magnetic Resonance (NMR) Spectrometry, and 2-D Heteronuclear Single Quantum Coherence (HSQC) NMR were leveraged to characterize raw and chemically modified soybean oils. The physicochemical properties of high oleic soybean oil (HOSO), chemically modified branched high oleic soybean oil (BHOSO), and high oleic sunflower oil (HOSuO) were analyzed and correlated with their tribological behavior. The reciprocating friction and wear performance of select lubricants were tested using a ball-on-flat type reciprocating tribometer at room and 100 degree C temperatures. It was observed that the utilized chemical modification process increased wear resistance by 10.6% at room temperature and 10.7% at 100 degree C operating temperature. Major differences in wear mechanisms were further analyzed using white light interferometry, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) techniques.