Modelling and optimization of polymer extrusion

Extrusion is a fundamental method of processing polymeric materials, used in the production of
commodities in diverse sectors such as packaging; household; automotive; aerospace; marine;
construction; electrical and electronic; and medical applications. Usually, extrusion is an energy
intensive production method and it is well-known that these processes often operate at poor
energy efficiencies. Although process energy efficiency is good at higher processing speeds, it is
difficult to run at these conditions as thermal fluctuations increase with increasing screw speed
resulting in very poor melt quality. Therefore, the majority of extrusion processes are operating
at conservative rates to control or avoid problematic thermal fluctuations and this leads to poor
energy efficiency. Since, global energy prices are increasing rapidly, plastics based
manufacturing companies are highly concerned about the energy efficiency of their production
plants in order to maximise profit margins. A major current concern in the industry is therefore to
determine how to optimise energy and thermal efficiency simultaneously while achieving the
required process output rate and melt quality. Relatively little work has been carried out so far on
process optimisation, and as there is no well accepted method in the industry to find optimum
process operating conditions where most process operators are still using trial and error
methods. Therefore, this project aims to explore process energy efficiency and melt thermal
quality within a single screw extruder using commercial grades of polymers. Correlation/s
between these two parameters will be explored leading to the development of process models to
achieve optimum energy and thermal efficiencies simultaneously. Eventually, it is expected to
use these models to develop an industrially applicable program to select optimum processing
conditions for polymer extrusion applications more quickly in a logical way.