Flow properties of polystyrene solutions under high shear rates

Abstract

synopsisThis manuscript reports on the development of a high-shear Couette viscometer. The main design considerations for a high-shear concentric cylinder viscometer are reviewed and discussed. I n principle, the instrument is identical to those used by other investigators. However, some modifications were found necessary. Attention is drawn to the importance of the concentricity problem. The instrument was first tested and calibrated using Newtonian standard oils. Then non-Newtonian runs were performed using narrow polystyrene standards of molecular weights 97,200, 411,000, and 860,000. Solutions of the polymer in n-butylbenzene ranged in concentration from 0.08 g/cc up to 0.5 g/cc. The shear rates applied ranged from 10' sec-1 up to 106 sec-1. The results obtained were compared to the molecular entanglement theory, and excellent agreement was observed.

The shear viscosity dependence on concentration, molecular weight, and shear rate of polystyrene solutions

“…This slope is in good agreement with the theory of Graessley (--0.82) [3] and other experimental data [20][21][22]. For the system polystyrene in n-butylbenzene, a limiting slope of -0.83 was found by Abdel-Alim et al [20] by evaluating the non-Newtonian region using a dimensionless coordinate master curve plot.…”

“…For the system polystyrene in n-butylbenzene, a limiting slope of -0.83 was found by Abdel-Alim et al [20] by evaluating the non-Newtonian region using a dimensionless coordinate master curve plot. Attan6 et al [21] observed a slope of about -0.85 for polystyrene in dibutylphthalate at sufficiently high concentrations.…”

“…In this context it must be noted that light scattering measurements made in our laboratory showed that the very high molecular weight polystyrenes were not degraded by prolonged shearing at the highest shear rates used in this study. AbdelAlim et al [20] checked for possible polymer degradation by GPC analysis. No difference was detected between the polymer samples before and after shearing up to ?…”

Green Blends Based on Ionic Liquids with Improved Performance for Membrane Technology: Perspectives for Environmental Applications

“…According to the results obtained, depending on the stress parameter value, the material structure undergoes reversible changes, reflected in the variation in viscosity highlighted in the rheological profile through three regions [ 35 , 36 ]. Thus, in the first region (Region I), when the viscosity decreases with increasing shear rate, a shear thinning regime (pseudoplastic behavior at low shear rates) occurs.…”

“…wt% and 15 wt% Cyphos IL 101), with the exception that in the range of low shear rates, the dynamic viscosity is higher than for PSFQ samples, and, starting from a certain shear rate of approximately 1.3 s −1 , a continuous decrease in the dynamic viscosity occurs, without showing the Newtonian plateau, becoming smaller than that of PSFQ. According to the results obtained, depending on the stress parameter value, the material structure undergoes reversible changes, reflected in the variation in viscosity highlighted in the rheological profile through three regions [35,36]. Thus, in the first region (Region I), when the viscosity decreases with increasing shear rate, a shear thinning regime (pseudoplastic behavior at low shear rates) occurs.…”