Screw extruders are one of the major processing machines in the polymer industry. Although the major continuous processing machine in the market has always been the single-screw extruder, in recent years there has been a growing industrial role for multiple, especially twin-screw extruders.

The co-rotating twin-screw extruder is a particularly versatile and flexible device which can be configured to provide an array of mixing functions in a desired sequence. This report considers the mixing functions which can range from intensive dispersive to laminar distributive, depending on the configuration of screw bushings, kneading blocks, distributive mixing units and/or other specialised element types along the shafts. Special feeding procedures which are needed for successful mixing of a product are also discussed.

This report describes the geometric structure of modular extruders, development of the various units of an extruder and their functions, the flow mechanisms and models of their behaviour and experimental studies of extruder performance and applications.

This report will be invaluable to those working in the polymer industry with twin-screw extruders, particularly plastics manufacturers, compounders, material developers and anyone who uses or is thinking of using twin-screw extruders.

Yeh Wang is a Professor at Tunghai University in Taiwan, where he lectures on polymer compounding, mixing and rheological testing. He is the author of over 50 publications in this field.

This review is accompanied by an indexed section containing more than 400 references and abstracts selected from the Polymer Library. These provide the reader with a valuable reference source for further information about compounding with co-rotating twin-screw extruders.