Steady-State and Oscillatory Flow Properties of Polymer Solutions

Abstract

Viscosities, first and second normal-stress differences, and related material functions were determined for steady-state and oscillatory shearing of polyethylene oxide and polyacrylamide solutions by use of a Weissenberg R-17 Rheogoniometer with cone-and-plate shearing geometry. Pressure transducers—located along the radius of the plate, with their 0.04-in-O.D. pressure-sensing membranes flush with the plate surface—were used to determine local values of the normal stress. The sensitivity of the transducers was 20–30 dynes/cm2 for steady-state and 10–15 dynes/cm2 for unsteady-state measurements. The ratio of the secondary to the primary normal-stress difference was negative, was as large as −0.2 for the solutions studied, and appeared to decrease with increasing shear rates over the shear-rate range investigated. Complex viscosity and displacement and amplitude functions for both the primary and secondary oscillatory normal-stress differences were determined as functions of the frequency. A significant improvement in the agreement predicted by the “analogies” between the oscillatory primary-normal-stress-difference functions and the complex viscosity functions was achieved in comparison with previous results by reduction of instrument compliance. The Spriggs four-constant and similar models, as well as the Carreau and Bogue-Chen models, were compared with our steady-state and oscillatory data, and these fit the data fairly well; but overall, the Bogue-Chen model appears to represent the data somewhat better.

Network theory of the nonlinear behaviour of polymer melts. Simple shear flow

“…This prediction is of great importance because there is still confusion concerning the sign of N 2 of polymer solutions and melts (7)(8)(9)(10)(11).…”

End effects for highly elastic-constant viscosity fluids

“…It is possible, for a very great variety of polymeric materials, to use a power-law expression for correlating the primary normal-stress difference as a function of shear stress [12]. At the same time, the assumption of a constant ratio, e, of the secondary and the primary normal-stress differences is reasonable in the light of the few reliable experimental data available in the literature [13][14][15]. Therefore, it can be shown that the nu-term is proportional to the so-called recoverable shear, SR, or the Weissenberg number, We (of Deborah number, De, for some numerical works).…”

Rheological properties of dilute polymer solutions: An extended thermodynamic approach

“…Comparison with experimental data will be performed with four polymeric solutions: a 2.5% solution of polyacrylamide in a 50% water and 50% glycerine solution (PAA) [41], a 1.1% polyisobutylene solution in decahydronaphthalene (Oppanol B200) [42], a 3% solution of polyethylene oxide in a 57%-water, 38%-glycerine and 5%-isopropyl-alcohol solution (PEO) [41,42], and a 8.7% polyisobutylenedecalin solution "D2b" (Oppanol BS0) [43]. (49) The reason for chosing the PAA and PEO solutions is that, in these cases, all three viscometric functions r/, ~, and ¢/2 have been determined experimentally (50) and that concomitantly, data concerning oscillatory shearing are also available.…”