High-Performance Lubricant Base Stocks from Biorenewable Gallic Acid: Systematic Study on Their Physicochemical and Tribological Properties

Synthesis, characterization, and evaluation of a series of gallate derivatives as lubricant base stocks are described. The gallate derivatives were synthesized via sequential esterification and alkylation reactions from biorenewable raw material gallic acid. All the synthesized gallate derivatives were structurally characterized by using NMR, IR, and HRMS spectral data. Their physicochemical and lubricating properties including density, viscosity, viscosity index, pour point, flash point, volatility, corrosion level, thermal and oxidation stability, and friction-reducing and antiwear properties were systematically investigated. On the basis of the physicochemical and lubricating data, it can be concluded that gallate derivatives have good properties in terms of viscosity-temperature characteristics, corrosion ability, volatility, and low-temperature flow ability. More important, they have predominant thermal and oxidation stability, as well as high-temperature friction-reducing and antiwear performances compared with the existing synthetic ester oils. These favorable technical performances together with their biological available resources recommend gallate derivatives as excellent base stocks for the development of high-performance green lubricant products. (Figure Presented).