Numerical study on the mixing performance of screw mixing elements and conventional screw elements

The flows of rigid polyvinyl chloride (R-PVC) in co-rotating twin screw extruders with screw mixing elements and regular screw elements were simulated by using the finite element method. The three-dimensional, non-isothermal flow fields of R-PVC in the two kinds of screw elements were calculated. The mixing performance of each type of element was studied by the particle tracking analysis method. The results show that the temperature distribution and shear-rate distribution are more uniform in the flow channel with screw mixing elements than in the flow channel with regular screw elements. Screw mixing elements provide better distributive and dispersive mixing performance but worse conveying capacity than regular screw elements.