A method to quantify the shear thinning effect for polymer-clay nanocomposites has been developed. It relies on the shear thinning exponent it. The method allows to compare the extent of delamination of platelet stacks based on a routine polymer characterization experiment. Since technical properties of nanocomposites are closely linked to delamination or exfoliation, the method helps to predict the level of properties of a nanocomposite. The method is expected to become a highly useful analytical tool in the development of nanocomposites from thermoplastic polymers and virtually all kinds of platy, fibrous, or dendritic filler materials with high aspect ratio. (C) 2003 Elsevier Ltd. All rights reserved.