Mixing in Single Screw Extruders
is a must-have practical guide to the subject of single-screw extrusion. Avoiding mathematical theory, except when absolutely necessary, this authoritative handbook empowers the reader to achieving good results with their plastic mixing. Mixing in Single Screw Extruders
will be a valuable resource to all involved in the art of plastic extrusion.
A lot of plastics products are extruded and most of those products contain additives, which mean that the plastic must be mixed at some point. Mixing is generally done with a twin-screw extruder, and the single-screw extruder, which is used in product production, is generally overlooked as a device for mixing. This reference handbook, written by a former Principal Consultant at Smithers Rapra, and the inventor of the cavity transfer mixer, redresses the balance.
Extrusion is used for about half of all plastics product manufacture, mostly using single screw extruders. Very often part of their role is the incorporation of one or more of a very wide range of additives, mainly in the form of masterbatches. These range from very visible colours to the invisible traces of anti-block and slip additives. There are also continuing pressures to improve overall economics and these require increased mixing performance in many cases.
With the growing pressures to increase the amount of plastics recycling, both the limitations and success in blending the mainly incompatible polymer combinations are explained.
The development of 'add-on' cavity mixers and floating ring mixers, together with their methodology are described, whilst the associated innovative techniques using liquid injection of colours, tackifiers, lubricants, crosslinking agents and foaming agents, (particularly carbon dioxide) are included. Developments in controlled levels of blending by 'chaotic mixing' to produce products with very specific properties such as barrier films is briefly described.
Extrusion tests for carbon black dispersion are included and the book concludes with a practical guide to the preparation of microtomed plastics specimens for evaluation by optical microscopy.