Effect of temperature, composition, and shear rate on polyvinylidene fluoride/dimethylacetamide solution viscosity

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) φC. 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.