Paper X(iii) High-shear viscosity studies of polymer-containing lubricants

This paper introduces an experimental technique and associated data analysis procedure for studying the shear dependent viscosity of oils containing polymers at shear rates up to 10 6 s −1 and temperatures up to 170°C, conditions which are typically experienced in operating engines. The experimental apparatus is a capillary viscometer with a controlled nitrogen gas pressure as the driving force and uses constant volume efflux bulbs to measure the oil flow rate. The main contribution of this work is the coupling of experimental calibration measurements and a theoretical analysis to develop a calibration procedure which can be used to extract accurate high-shear rate viscosity data from capillary viscometer measurements when the fluid viscosity is being influenced by temperature, pressure, and shear rate.