Melting performance in the single screw extrusion of thermoplastics

Abstract

Abstract Melting performance experiments involving three different thermoplastics and three different screw designs have been carried out on a well‐instrumented single screw extruder equipped for cold screw extractions. In the case of the particular polystyrene used it was possible to deduce, from measurements made on the extracted screw, the velocity, and hence acceleration, of the solid bed of compacted polymer at points along the screw channel. The experimental results are successfully compared with the performance predicted by a previously established model, the most important feature of which is the ability to allow the solid bed to deform freely and hence to accelerate. The results show that the bed does indeed suffer significant and non‐uniform acceleration and that the model can predict both this acceleration and the resulting bed break‐up which leads to surging.