1. Extrusion defect phenomenon

1.1 Definitions and terminology

The economic balance sheet for the extrusion of mass-produced thermoplastic polymers – polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS) – is determined solely by the extrusion throughput in terms of meters of film, sheet or tube, or the number of finished objects per minute. It is necessary to achieve the highest possible extrusion throughput for these polymers, millions of tons of which are produced every year. The situation is different for engineering plastics – polyamide (PA), polycarbonate (PC), and polyesters – whose prices are higher (by a factor of three or more), and for which the higher value of the end application may allow a slower extrusion process. However, extruder operation at high output rates is limited...