Abstract
Tip clearance between two screws and/or screw and barrel plays an important role in the mixing performance of twin screw extruders (TSEs). We introduces special kinds of TSEs that have variability of tip clearance. We performed computational analysis of flow in the fully-filled melt mixing zone of TSEs with special geometries including grooved barrel and multi-clearance kneading disk, by using a finite element method. We discussed the distributive mixing, dispersive mixing, viscous heat generation, etc. for special geometries as well as the conventional one. The results revealed that the variability of tip clearance enabled the averaged shear stress exerted on the polymer materials to be larger for both special barrel and screw. The grooved barrel also showed better distributive mixing due to the complicated flow in the groove and suppression of the maximum viscous heating. An experimental result suggested that the grooved barrel had the advantage of mixing performance in comparison with the conventional one.
