Energy efficiency in extrusion-related polymer processing: a review of state of the art and potential efficiency improvements

Energy saving and industrial pollution have become increasingly important issues, therefore the identification and adoption of more energy efficient machines and industrial processes are now industrial priorities, and worthy topics for further development through academic research. Polymeric materials are a major raw material, finding widespread application to a range of current industrial machine components as well as multiple products and packaging found in our daily life. Polymer extrusion serves as a particular example of polymer processing techniques, representative of others in as much as there are analogous intermediate stages in the processing. Processing techniques which require such intermediate stages include the manufacture of blown film, blow moulding, thermo-forming, and injection moulding. Hence, the study of polymer extrusion is a representative paradigm for a wider range of processing techniques. Since polymer processing is an energy intensive process and accounts for a huge share (maybe more than 1/3) of the materials processing sector, any improvement to the process would contribute significantly to global energy savings. This work presents a review of studies, which focus on, or appertain to, the energy consumption of extrusion related polymer processing applications. Typical energy demand and losses during processing are considered, and possible approaches for improving the process energy efficiency while maintaining the required end product quality are considered. Overall, this work provides a detailed discussion about how and where energy is utilised; how, where and why energy losses occur; and sets out approaches for optimising the process energy efficiency.