The effect of starch volume fraction on starch-filled poly(hydroxy ester ether) (PHEE) biodegradable composites was analyzed using Mooney, Thomas, Maron & Pierce, and kankel & Acrivos equations. Corn starch/PHEE materials were extruded using a twin-screw extruder with starch volume fractions from 0.27 to 0.66. The starch was dried to a moisture content of 0.7Oh to minimize moisture effect on composite rheology. Dynamic fresuency sweep measurements were canied out at 120°C and 104 strain. The equations of Maron & Pierce, Thomas, and Frankel & Acrivos can be used to describe the experimental data. It is found that the relative viscosity at the same shear stress increases with increasing shear stress. The possible existence of yield stress at high starch concentrations was examined using a Casson plot.
Hydrodynamics characteristics like flow pattern, shear rate distribution, power consumption, axial pumping capacity, mixing time, and mixing efficiency of an ellipse gate (EG) impeller were investigated by experimental and numerical methods. The numerical simulation results were validated by experimental data of power consumption and mixing time. Results indicate that the axial pumping number of the EG impeller is larger than that of any other reported large-scale impeller under laminar regime, and that the shear rate formed by this impeller is less sensitive to Reynolds numbers. In-depth analysis reveals the different function of each part of the EG impeller under different flow regimes. This impeller provides an almost similar mixing efficiency like the double-helical ribbon impeller under laminar regime, but much higher mixing efficiency both under transitional and turbulent flow regimes.
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