Polymers Go with the Flow

摘要

The flow of polymers, either as melts or in solution, shows some intriguing features. Polymeric liquids climb stir-rer rods (the Weissenberg effect), swell up at the exit of an extruder or capillary, and can even sustain tubeless siphons. These phenomena cannot be explained by classical hydrodynamics. Yet they are typical of most polymeric substances, independent of their chemical composition. On page 1691 of this issue, Bent et al. (3) show that theoretical understanding of this "universal" behavior has advanced so far that it can quantitatively reproduce the properties of a complex flow similar to those encountered in applications.