Mixing mechanism of three-tip kneading block in twin screw extruders

In recent years, twin screw extruders have been applied to various kinds of polymer processing. It has been important to find their optimum geometrica l configurations and operational processing conditions for the best perform ance of extrusions and products. Many engineers have been evolving numerica l and the experimental methods to characterize the mixing performance for t win screw extruders. We have carried out three-dimensional now simulations of kneading blocks in intermeshing co-rotating twin screw extruders by usin g the finite element method to quantify their ability in distributive and d ispersive mixing. We discuss their performance in distributive mixing for t hree different type of kneading blocks in terms of the residence time distr ibution and the nearest distance between markers at various periods of time , by using the marker tracking method. Those numerical techniques and appli cations of mixing indices have enabled us to quantify and evaluate their ab ilities in distributive mixing of kneading blocks in twin screw extruders.