The film‐forming properties of polyalkylene glycols

It is now recognised that, for many practical applications, an important property of a lubricant is its ability to generate thick, elastohydrodynamic (EHD) films in concentrated contacts. This paper describes a study of the EHD film- forming properties of polyalkylenie glycol lubricants. A wide range of polyglycol structures have been examined, with different monomer types, initiators, and molecular weights. Film thickness has been measured at several different temperatures using both conventional and ultra-thin film interferometry. From the measured film thicknesses, the effective pressure–viscosity coefficients of the lubricants have been evaluated. This has enabled a systematic investigation of the effect of polyalkylene glycol structure on both pressure–viscosity coefficient and EHD film formation.