Rheological properties of polyethylene oxide solutions

Abstract

Measurements were made on solutions of Polyethylene oxide (WSR-301) varying in concentration from .0511 g/dl to 4.014 g/dl, prepared from two samples of dry material of different ages (I, II), using aWeissenberg Rheogoniometer with cone-and-plate and parallel-plate geometries, and also using capillary viscometers. Steady shear data were obtained for eight decades of strain-rates (10−3 <k < 105 sec−1), and oscillatory data for over four decades of frequency (10−3 <f < 101 Hz). Results are presented for the shear-dependent viscosity,η(k), normal stress differences,σ 1(k), σ2(k), and the complex viscosity,η *(f). It was found that characteristic fluid times obtained from continuum arguments correlated the experimentalη(k), η′(f) andG′(f) data. Using theη *(f) data, the stress relaxation function,Ψ(σ), was calculated, from which the second-order fluid coefficientsγ andη 0 were obtained, and compared to the directly measured values. Evidence is given to show that the sign ofσ 1(k) varies both with concentration and strainrate. Using solutions prepared from sample II, correlations with the material properties of solutions of sample I were found which indicated the effect of aging on stored dry samples.