A Mechanism of Thermo-oxidative Degradation of Polyol Ester Lubricants

Abstract

Polyol ester lubricants are used in a wide range of temperature conditions, normally from ‐ 54 up to +220 °C, and their application can be limited by high tem perature oxidation leading to viscosity increase, sludge and/or formation of d eposits. This paper is concerned with the chemical processes which take place during the oxid ation of esters, particularly polyol esters, and discusses the selectivity of oxygen attac k on ester molecules, and the formation and decomposition of hydroperoxides as well as other pr oducts formed as a result of ester oxidation. Proposed mechanisms of polyol ester lubricant oxidation are discussed, and unresolved problems which require additional research efforts are revealed.