Analyzing the effect of isopropylation on regular and high oleic soybean oil: A lubrication behavior perspective

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

Submitted to: Royal Society of Chemistry Advances
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2025
Publication Date: 4/10/2025
Citation: Bhowmik, P., Sarker, M.I., Sharma, B.K., Wang, Y., Tang, C., Roy, S. 2025. Analyzing the effect of isopropylation on regular and high oleic soybean oil: A lubrication behavior perspective. Royal Society of Chemistry Advances. https://doi.org/10.1039/d5ra00058k.
DOI: https://doi.org/10.1039/d5ra00058k

Interpretive Summary: Scientists around the world are putting a lot of effort in developing lubricants from natural oils in response to the decline of mineral oil reserves and the adverse effects of environmental contamination. Soybean, a highly cultivated crop on a global scale, has been recognized as a promising candidate for this type of oil. However, soybean oil isn't very stable when it comes to heat and oxygen, which necessitates measures to ensure that lubricants made from soybean oil can work well in situations where temperatures are high. In order to solve this problem, the process called, isopropylation was employed to chemically modify both regular soybean oil (RSO) and high oleic soybean oil (HOSO). During this process, the carbon-carbon double bonds of fatty acids undergo conversion into single bonds. In order to confirm the formation of single bonds, a series of tests including GC-MS, NMR, and compact mass spectroscopy (CMS) analyses were conducted. The modified oils were also compared for their tribological qualities under varying temperature settings. The chosen chemical modification process had a greater effect on the lubrication properties of RSO compared to HOSO. At room temperature, the wear volume of RSO was reduced by 35%, while at high temperature, it was reduced by 15%. In contrast, HOSO only experienced a reduction of around 10% in wear volume at both room and high temperatures. The tribological behavior was thoroughly analyzed to investigate the primary wear mechanisms in each scenario.

Technical Abstract: Researchers around the world are focusing on the development of lubricant from natural oils due to the depletion of mineral oil and environmental pollution. Soybean, which is one of the most produced crops globally, has been identified as a potential source for such oil. However, soybean oil has poor thermal and oxidative stability, which needs to be addressed so that soybean oil-based lubricants can perform reasonably at relatively high temperature applications. To overcome this, isopropylation based chemical modification was used on both regular soybean oil (RSO) and high oleic soybean oil (HOSO). During this process the carbon-carbon double bonds of fatty acids also get converted to single bonds. To ensure the formation of single bonds, various tests such as GC-MS, NMR, and compact mass spectroscopy (CMS) analyses were performed. The tribological characteristics of the oils were also compared at different temperature conditions. It was observed that the selected chemical modification process was more impactful on RSO from a lubrication perspective, resulting in a 35% reduction in wear volume at room temperature and a 15% reduction at high temperature, compared to only around a 10% reduction for HOSO at both room and high temperatures. Detailed analyses of tribological behavior were conducted by leveraging a suit of microscopy, spectroscopy and interferometry techniques exploring the dominant wear mechanisms in each case.