Comparative analysis of oleate esters as ester-based synthetic lubricating oils: a physicochemical, quantum, and functional study

Abstract

This study presents a comparative analysis of oleate esters synthesized from oleic acid and various alcohols (ethylene glycol, glycerol, and pyrogallol) as potential ester-based synthetic lubricating oils. The physicochemical and functional properties of the synthesized esters were characterized using Fourier Transform Infrared (FT-IR) and Nuclear Magnetic Resonance (1H-NMR) spectroscopy, confirming successful ester formation. Thermal stability was assessed via thermogravimetric analysis (TGA), revealing a maximum stability of 400 °C. The esters exhibited remarkable performance characteristics, including flash points of 220–225 °C, viscosities ranging from 70 cSt to 73 cSt at 40 °C, and superior viscosity indices compared to commercial lubricants. Additionally, the prepared esters displayed excellent low-temperature fluidity with pour points between −33 °C and −42 °C. Rheological studies indicated that the esters behave as Newtonian fluids, maintaining stable viscosity across varying shear rates. Quantum studies further indicated that the stability order of the esters is OP > OG > OE, highlighting the significant potential of these oleate esters in lubrication applications.