Optimization of rotor speed based on stretching, efficiency, and viscous heating in nonintermeshing internal batch mixer has been investigated using polymer melt. A practical optimization technique was followed for optimization. Four different rotor speeds were used and characterized numerically with viscous dissipation and stretching. The heat distribution between rotor edge and mixer wall was calculated. Stretching experienced by the fluid was analyzed and the result was verified experimentally using particle tracking method. Exponential increase of energy dissipation between the rotor edge and the barrel at higher speed highlighted the importance of choosing the thermal properties of the polymer to avoid thermal degradation.
The effect of natural exposure and artificial weathering on selected properties of PP/EVA blends was investigated. The vinyl acetate concentration decreased with exposure time due to acetylation. The most pronounced effect of radiation is associated with oxidative degradation. The cross-linking of PP/EVA blends was attributed to the formation of vinylidene group. Weathering decreased the tensile strength, elongation at break, and Young's modulus of the naturally and artificially exposed blends. This reduction was the result of blends' molecular weight reduction due to the degradation induced by weathering.
Possibility of generating strong secondary flow in mixing region of twin screw extruder was analyzed numerical FEM simulation using the commercial CFD package Polyflow. Adaptive remeshing - mesh superposition technique was used to generate high density polyethylene velocity profiles in simulation. Clearance between barrel wall and mixing element was increased gradually and observed the changes in flow pattern. Mixing element tip radius was varied by ratio to generate convergence flow in the clearance region and visualize the strength of secondary flow profile. Strong secondary flow at the clearance channel can generates elongation flow and improves the dispersive mixing; helps to decrease the screw length by minimizing kneading disc number in mixing section.
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