Effect of temperature and shear rate on polyisoimide solution viscosity

Abstract

The following models describe the effect of temperature and shear rate on the viscosity of polyisoimide solutions.Data was obtained for 20, 30, and 40% polyisoimide solutions in 20:80 tetrahydrofuran/diglyme and for a 30% solution in N-methyl-pyrrolidone at temperatures of 25". 35". 55", and 75°C. The measurements were taken on a Brookfield cone and plate viscometer at shear rates ranging from 9.59 to 383.4 reciprocal seconds. Experimental data fits model (1) reasonably well. In some cases, model (2) provides a better fit. This model accounts for temperature dependencies in the power law shear-thinning exponent.The coefficients p depend on the material lot that is being tested even though the lot molecular weights are very close. Slight differences in acid functional group concentrations for this particular material are a possible explanation.

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

“…Viscosity also increases with increasing polymer concentration in exponential form η = A 2 e D W where A 2 and D are fitted parameters while W is the polymer mass fraction. The above equations (eqs , , and ) can be combined to study the effect of polymer melts and solution viscosities as a function of shear rates, temperature, and polymer concentrations τ = ( K · A 1 · A 2 ) γ ̇ n e C / T e D W Combining the empirical constant of eq leads to τ = A γ ̇ n e C / T e D W The effect of temperature and shear rate on a polyisoimide solution viscosity was investigated . Data were obtained for 0.20, 0.30, and 0.40 mass fraction polyisoimide solutions in the ratio of 20:80 tetrahydrofuran/diglyme and for a 0.30 mass fraction solution in N -methyl-pyrrolidone at temperatures of (25, 35, 55, and 75) °C.…”

“…The effect of temperature and shear rate on a polyisoimide solution viscosity was investigated. 4 Data were obtained for 0.20, 0.30, and 0.40 mass fraction polyisoimide solutions in the ratio of 20:80 tetrahydrofuran/diglyme and for a 0.30 mass fraction solution in N-methyl-pyrrolidone at temperatures of ( though the molecular weights are very close. Slight differences in acid functional group concentrations for this particular material are a possible explanation.…”

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

“…Newtonian fluids are defined as those exhibiting a direct proportionality relationship between shear stress and shear rate, whereas for non-Newtonian fluids, the relationship between shear stress and shear rate is not linear. Pseudoplastic fluids are called shear thinning fluids, because their apparent viscosity decreases with shear rate; hence, increased shearing breaks down the internal structure within the fluid rapidly …”

“…The viscosity of polyisoimide solutions was studied by Levinson et al; two models were developed, to describe the effect of temperatures and shear rates on the viscosity. The data were obtained for various polyisoimide solutions prepared in different ratios of oxolane/diglyme in 1-methyl-2-pyrrolidone (NMP), and the viscosity of the polymer solutions was tested at various temperatures.…”

“…Pseudoplastic fluids are called shear thinning fluids, because their apparent viscosity decreases with shear rate; hence, increased shearing breaks down the internal structure within the fluid rapidly. 1 The viscosity of polyisoimide solutions was studied by Levinson et al; 1 two models were developed, to describe the effect of temperatures and shear rates on the viscosity. The data were obtained for various polyisoimide solutions prepared in different ratios of oxolane/diglyme in 1-methyl-2pyrrolidone (NMP), and the viscosity of the polymer solutions was tested at various temperatures.…”