Measurements of the Normal Stress Effect in Solutions of Polyisobutylene

Abstract

Weissenberg^1–3, Garner and Nissan⁴, and Garner, Nissan and Wood⁵ have described a number of experiments which indicate that, in high-polymer solutions, steady-state laminar flow cannot be maintained by the action of shearing forces alone, even at low-velocity gradients for which centrifugal effects can be neglected. The effects observed in these oxperi-ments have been interpreted by Rivlin^6,7phenomeno-logically as due to the fact that the relations connecting the stress and strain velocity components for the steady-state laminar flow of such a solution involve a second physical parameter denning the flow properties of the fluid, in addition to the viscosity.