Analyzing the effect of isopropylation on regular and high oleic soybean oils: a lubrication behavior perspective

Researchers around the world are focusing on the development of biobased lubricating 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 in 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.