Ester Oils Prepared from Fully Renewable Resources and Their Lubricant Base Oil Properties

Abstract

The work reports on the physicochemical and tribological properties of gallate ester oils prepared from fully renewable resources, such as gallic acid and fatty acids. The ester structures were identified by proton nuclear magnetic resonance spectroscopy ( 1 H NMR), carbon nuclear magnetic resonance spectroscopy ( 13 C NMR) and high-resolution mass spectra (HRMS) data. The density at 20 °C ( d 20 ), kinematic viscosity (KV), viscosity index (VI), pour point (PP), flash point (FP), thermal and oxidative stabilities, friction-reducing and antiwear properties of gallate ester oils were evaluated. The tribological properties of gallate ester oils as lubricants for steel, copper, and aluminum tribo-pairs can be compared with those of the commercially available lubricating oil tris(2-ethylhexyl) trimellitate (Phe–3C i8 ), but their viscosity-temperature characteristics, thermal and oxidative stabilities are better than those of Phe–3C i8 . More importantly, they have much higher biodegradabilities than Phe–3C i8 . The study of the lubrication mechanism shows that the physical and/or chemical adsorption film formed by gallate ester molecules between friction pairs is the key factor for them to obtain friction-reducing and antiwear properties.

A Novel Approach of Bioesters Synthesis through Different Technologies by Highlighting the Lowest Energetic Consumption One

“…Comparable results were also obtained for erythritol tetra myristate and erythritol tetra laurate esters [ 50 ] or lubricants of the type gallate ester oils, respectively [ 51 ].…”

Facilitating Investigations of Sustainable Ester Oils: Lubricating Performance, Phytotoxicity Indicators, and Their Structure–Activity Relationship

“…This is consistent with the literature reports. 38 In addition, the viscosity index increases with the increase of the chain length of substituted alkoxy groups, 39 such as PIS (VI = 81.2) < PETO (VI = 184.3). The viscosity index decreases with the number increase of the ester groups, for instance, PETO (VI = 184.3) < TMPTO (VI = 189.7).…”

Influence of Molecular Structure on the Physicochemical and Tribological Properties of Biolubricants: A Review

“…The areas most affected by this phenomenon are the carbons atoms located between two double bonds, so that the oxidative stability of the structure decreases as the areas of oxygen attack increase [57,78,79]. This oxidative stability refers to the ability of lubricants to retain their properties when exposed to environmental oxygen without suffering oxidative degradation [80]. It has also shown an increase in PP and a tendency to increase viscosity and decrease viscosity index (VI) by reducing the content of unsaturated FAs [57,78,81].…”