Rheological behavior of polyvinylidene fluoride/dimethylacetamide solutions: Experimental investigation and machine learning modeling

This study aimed to investigate the rheological properties of polyvinylidene fluoride/dimethylacetamide solutions. The influences of shear rate, temperature, and additives fractions on solution viscosity were experimentally studied. The results indicated that the viscosity is noticeably reduced by increasing the temperature at low shear rates, while the temperature dependence of viscosity was diminished at high levels of shear rate. On the other hand, adding water to the solution tended the viscosity to increase, especially at lower shear rates and temperatures. Furthermore, an exponential enhancement was observed in the viscosity by growing the inorganic/organic additive ratio. The measured data were employed to design predictive methods for solution viscosity by defining six factors including temperature, shear rate, and the fractions of solvent and additives as input variables. The modeling phase was carried out by implementing three computer-aided approaches, among which the radial basis functions (RBF) method overcame the others from the standpoint of accuracy and reliability with total average absolute relative errors and R2 values of 1.29% and 99.86%, respectively, for 1064 measured data. Also, a visual description through the contour diagram affirmed that the RBF model performs excellently in the suit of describing the rheological behavior of the polymeric solution under various operating conditions. Eventually, the factors with the greatest influences on solution viscosity were designated through a sensitivity analysis based on the recently proposed model.