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Chemical modifications of vegetable oils may be applied for the purpose of improving their physicochemical properties in their usage for the bio‐based lubricants. The vegetable oils with a high percentage of oleic acid, such as soybeans and rapeseed oils, are important raw materials to obtain the biolubricants. In this particular study, the oleic acid was esterified with 1‐octanol, followed by epoxidation. The oxirane ring opening reaction was performed using different alcohol structures (linear, branched, and cyclic), in order to evaluate their influence on the final physicochemical properties with the synthesized samples. These aforesaid reaction steps were followed by 1H nuclear magnetic resonance and the main physicochemical properties in the intermediate and final samples were assessed. The highest oxidative stability was observed for the samples obtained, using a cyclic alcohol at the oxirane ring opening reaction (230 min), followed by the linear alcohols with the branched alcohol presenting the lowest oxidative stability (124 min). The pour point values for the samples synthesized with the branched alcohol were slightly better than those with the linear and cyclic alcohols. All the synthesized samples showed high viscosity indexes (>130) and kinematic viscosities at 40 °C, ranging from 30 to 33 cSt (application degree ISO VG‐32), which are adequate for their use in the formulation of bio‐based lubricants.

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 1H 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.

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