Molecular Dynamics of Synthetic-Based Lubricant System by Spectroscopic Techniques—Part 1

Abstract

This article describes the structure–property relationships of synthetic pentaerythritol polyol esters (PEE) and polyalphaolefins (PAO) as established by the diffusion and mobility measurement and tilt angle results obtained by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic techniques, respectively. The diffusion coefficients (D) were found to be dependent on the molecular structure, alkyl chain length, shape and size, hydrodynamic volume, and alignment of the molecules in a lubricant system constituting these base stocks. The viscosity–temperature and viscosity–pressure properties such as viscosity index (VI), pour point (PP), elastohydrodynamic (EHD) film thickness, pressure–viscosity coefficient (α), hydrodynamic volume, and radius are explained on the basis of the variation in D with temperature and tilt angle on the smooth surfaces. The study has enabled us to propose a molecular structure of a synthetic molecule that can be molecularly engineered to have high-performance physicochemical properties.

KEY WORDS:

• EHD
• Hydrodynamic Volume
• IR
• NMR
• Polyol Esters
• Pressure-Viscosity Coefficient
• Structure-Property Relationship
• Synthetic Base Oil

Acknowledgments

Review led by Paul Bessette