Diblock Polymeric Friction Modifier (PFM) in the Boundary Regime: Tribological Conditions Leading to Low Friction

The aim of this paper is to investigate the tribological conditions required to obtain low friction with a diblock PIB-PEG polymer friction modifier (PFM) blended in base oil (PAO4 + 1% wt PFM) under a severe lubrication regime. Two tribological conditions, rolling/sliding and reciprocating pure sliding, were investigated. A very low friction coefficient (μ ~ 0.035) was obtained at a temperature of 100 °C whatever the tribometer used. ECR measurements, ToF-SIMS characterizations of wear tracks and AFM analysis suggested the presence of an adsorbed polymer film on the rubbing surfaces. ToF-SIMS characterizations showed that the polymer bonds to the steel substrate through polar functions.