Extruders, extrusion melting mechanism

The objective of this work is to investigate the effect of various parameters, namely, shear viscosity, thermal conductivity, heat capacity, barrel temperature and screw temperature, on the melting mechanism in a single-screw extruder by performing three-dimensional simulation of the two-phase flow in melting (compression) region of the extruder. The numerical results are then compared with the corresponding extrusion experiments. 

As the screw turns, it conveys the pellets from the feed zone towards the melting zone. A combination of external heating and mechanical work melts the polymer as it is transported towards the metering zone. The metering zone pumps a uniform stream of molten polymer to a forming device, such as a profile die. Other types of extruders that employ two or more screws are commonly used for compounding polymer blends. The principles of twin screw extrusion will be discussed in Chapter 12. 

The fundamental processes and mechanisms that control single-screw extrusion are presented in Chapters 5 through 8. These processes include solids conveying, melting, polymer fluid flow, and mixing. The analyses presented in these chapters focus on easily utilized functions needed to assess the operation of the single-screw extruder. The derivation of these relationships will be presented in detail in the appendices for those who desire to explore the theory of extrusion in more detail. 

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