Transient stress responses predicted by the internal viscosity model in elongational flow

Abstract

Predictions are made for the elongational-flow viscosity growth function η e +(t) of the dilute-solution internal viscosity (IV) model developed earlier by Bazua and Williams. For calculating η e +,a novel treatment of the initial rotation of chain submolecules is required; such rotation occurs in response to the macroscopic step change of elongational strain rate at t = 0. The major role of IV is to cause the following changes relative to the Rouse Model: (1) abrupt jump at t = 0 for η e +; (2) general time-retardance of response.