1/ f α noise in aqueous solutions of poly(ethylene oxide) in Couette flow

Current-noise spectra have been determined for aqueous solutions of poly(ethylene oxide) subjected to different shear rates in a Couette-type measuring cell. Different electrode arrangements did not influence the results obtained. The current noise had a 1/fα-type frequency distribution, with the value of α depending on the shear rate, the molecular weight, and the concentration. At low shear rates, below 50 s−1, the current-noise intensity was immeasurably small. In general, the degree of pseudoplasticity of the solutions was reflected in the noise intensity and the value of the exponent α; non-Newtonian solutions give rise to a more intense noise. This tendency was expressed quantitatively in an inverse-type relation between α and n, the exponent of the pseudoplasticity in the Ostwald-deWaele power law of flow. The relation was slightly affected by the conditions of measurement. Newtonian solutions appeared to be associated with pure 1/f noise (α?1).