Clarifying the effect of rheological parameters of starch fluid on tensile properties of final extrudate in twin‐screw extrusion by numerical simulation

Abstract

AbstractThe distribution of the flow field, the input energy of the twin‐screw, and the dissipated energy on the fluid during the twin‐screw extrusion process were calculated by the POLYFLOW software to establish the relationship between the rheological parameters of starch fluid and tensile properties of the final extrudate. The results demonstrated that the pressure difference, the input energy of the twin‐screw, and the dissipated energy on the fluid were directly proportional to the zero‐shear viscosity (η0), reduced with the raise of the relaxation time constant (λ) and raised with the raise of the power‐law index (n). When the moisture content of starch fluid raised, the η0 value reduced, whereas the λ value and n value increased. The pressure difference, the input energy of the twin‐screw, and the dissipated energy on the fluid decreased, reducing the maximum tensile force of the final extrudate. Through numerical simulation and experimental verification, it was found that the changes of η0 value, λ value, and n value restricted each other on the tensile properties of final extrudate. Based on the numerical simulation, the tensile properties of the final extrudate could be predicted through rheological parameters of starch fluid.Practical ApplicationsA method was established to predict the final extrudate properties based on rheological parameters and numerical simulation in this study. Based on the numerical simulation, the tensile properties of the final extrudate could be predicted through rheological parameters of starch fluid. This research will provide insight into the mechanism of twin‐screw extrusion of starch‐based materials.