Rheological Behavior of Some Polymeric Sizing Agents Alone and in Admixtures

Solutions of seven polymeric sizing agents, viz., four kinds of poly vinyl alcohols (PVAs), carboxy methyl starch (CMS), and sodium polyacrylate (PA) in addition to their binary mixtures, at a concentration of 10%–-were rheologically characterized at 80°C. It was found that: (1) all these solutions behaved as non-Newtonian shear thining fluids that displayed measurable thixotropic character, and (2) the apparent viscosity, at a constant shear rate, and the extent of thixotropy depended both on the kind of sizing agent and on the composition of the binary mixtures. The flow behavior index and the shear thining index of each solution, as deduced from the power law, were estimated, and hence the degree of pseudoplasticity and the flow properties of each solution were evaluated.