Potential Bio-Based Lubricants Synthesized from Highly Unsaturated Soybean Fatty Acids: Physicochemical Properties and Thermal Degradation

The use of mineral lubricants and petroleum derivatives has become, along the years, harmful to the environment, so renewable raw materials have gained expressive notoriety. The innovation of this study is to understand how the highly unsaturated content from soybean oil influences the physicochemical properties and the thermal behavior of synthesized biolubricant base stocks. The process used was carried out in three steps: esterification with 2-ethylhexanol, epoxidation, and oxirane ring opening with 2-ethylhexanol. The modifications were monitored by 1 H NMR, the main physicochemical properties were measured, and the thermogravimetric behaviors of products were evaluated. The synthesized samples had high viscosity indexes (VI > 120) and viscosities that fit in application grade ISO-32. The samples using highly unsaturated fatty acids had a better pour point (−12 °C). The raw material composition directly influenced the physicochemical properties but did not affect the thermogravimetric behavior.