Effect of Temperature, Composition, and Shear Rate on Polyvinylidene Fluoride/Dimethylacetamide Solution Viscosity

Abstract

Viscosity required for casting or spinning dope polymeric solution plays an essential role in the formulation of flat sheets and hollow fiber membranes. A flat sheet membrane can be casted from a polymer dope with viscosity as low as a few hundred centipoises; by contrast, a few thousand are required to spin polymeric hollow fibers. In this study, an empirical correlation describing the effect of temperature, polymer mass fraction, and shear rates on the viscosity of polyvinylidene fluoride polymer in dimethylacetamide solvent was derived. The dope polymer was used in the fabrication of polymeric hollow fiber membranes engaged in building membrane contactors for water treatment and the removal of carbon dioxide from natural gas. Data were obtained for (0.10, 0.15, 0.20, and 0.25) mass fraction of polyvinylidene fluoride in dimethylacetamide solvent at temperatures of (25, 35, 45, 55, 65, and 80) °C. The predicted values by the correlation were in good agreement with the experimental data. This empirical correlation accounts for temperature dependencies in the power law shear-thinning exponent. The correlation was derived using a nonlinear regression technique and statistical analysis software.

The relationship between poly(lactide‐co‐glycolide) monomer ratio, molecular weight and hollow fibre membrane scaffold morphology

“…This trend was seen for the four dope concentrations tested: 10, 20, 25 and 30%. At any given PLA content and solution concentration, the viscosity decreased with increasing temperature, as expected because viscosity of polymer solutions is proportional to e 1/ T 21. A polymer concentration of 10% was too low for spinning in the case of all the polymer solutions tested, all being below 0.12 Pas.…”

Effects of Shear Rate, Temperature, and Polymer Composition on the Shear Stress of Polyethersulfone/1-Methyl-2-pyrrolidone Cast Solutions

“…The Andrade equation describes the temperature reliance of liquid viscosities . In the present work, a more comprehensive model adopted from the parabolic shape is used in fitting the experimental data. , normalτ = A false[ false( 1 + B − 1 true normalγ falsė false) m − 1 false] m − 1 e C T − 1 e D false( 100 W false) where τ/Pa is the shear stress, γ̇/s –1 is the shear rate, and A /Pa, B /s –1 , C /K, D , and m are empirical parameters. T /K is the temperature, and W is the mass fraction of PES in NMP.…”

Analysis and Modeling of Viscosity for Aqueous Polyurethane Dispersion as a Function of Shear Rate, Temperature, and Solid Content

“…Therefore, eq 8 for predicting zero shear viscosity can be obtained, where C is the constant. Al-Zahrani and Al-Fariss 44 and Ghasem et al 45 reported that the viscosity of polymer liquid varies exponentially with the concentration as follows where D is a constant and Ø is the content. From the Section 3.4 , the relation between viscosity and solid content follows the principle.…”

“…Parameters in eq 11 can be determined by least square nonlinear regression analysis on 160 sets of experimental data. For further comparison, two five-parameter correlations of the viscosity for waxy oils and dimethylacetamide solution proposed by Al-Zahrani 44 and Ghasem 45 were selected. Their correlation equations are as follows …”