Pressure influences upon shear thickening of poly(acrylamide) solutions

Abstract

This paper provides experimental data, measured with a Bohlin VOR viscometer and a Haake Searle-type high temperature and high pressure viscometer, which describe the shear thickening behaviour of a poly(acrylamide) in various glycerol-water mixtures. The influence of the glycerol content, the polymer solute concentration, the presence of salts and also the variation of the temperature and the pressure upon the shear thickening properties and associated descriptive parameters are reported. A proposed mechanism for the observed shear thickening behaviour, due to the formation of transient networks between the oriented and stretched polymer chains, under the action of the high shear forces is tentatively presented. The influence of the above variables upon the formation of a proposed interconnected network is discussed and the influence upon the rheological response is considered.