Study On The Mixing Section Of Intermeshing Counter-Rotating Twin Screw Extruder

Because of its positive displacement pump mechanism, so exhibit great yield, very narrow residence time distribution and strong ability to build pressure, intermeshing counter-rotating twin screw extruder are mainly used for extrusion of polymer products. But when it is used for polymer modification, mixing section must be equipped in the screw configuration, i.e. adding mixing elements in screw configuration to improve its mixing capability and extend the application fields.In this research, By comparing the mixing performance of kneading blocks in intermeshing co-rating and counter-rotating twin screw extruders, fulfill the design of the mixing section in intermeshing counter-rotating twin screw extruder.The three-dimensional isothermal flow fields of screw elements in mixing section were numerical simulated with professional Computational Fluid Dynamics package POLYFLOW. Through the results postprocessor, velocity profile, pressure profile, shear stress profile, backflow rate, residence time distribution and cumulated max shear rate distribution were obtained to analyze the mixing ability. It showed that mixing elements had more intensive shear (except S element),larger backflow and wider residence time distribution compared to common screw element thus have better mixing ability.The mixing performance of screw configurations with mixing section on immiscible blend was investigated. By analysising the morphology of online and die samples, it showed that screw configuration with mixing section had better mixing performance than common screw configuration.