Rubber bands as model polymers in Couette flow

Abstract

We present a simple device for demonstrating the essential aspects of polymers in flow in the classroom. Rubber bands are used as a macroscopic model of polymers to allow direct visual observation of the flow-induced changes in orientation and conformation. A transparent Perspex Couette cell, constructed from two sections of a tube, is used to create the simple flow developed by the relative motion of the two cylinders. This simple, qualitative visual demonstration of the flow behaviour of rubber bands in a transparent Perspex Couette flow cell shows flow alignment at low concentrations in glycerol in accord with expectation. At higher concentrations, an intriguing flow-induced 'balling' of ..