ABSTRACT
A single screw extruder is shown in Figure 10.1. Granules of a polymer are fed into the feed hopper. These granules become compacted, forwarded, heated, and mixed. (The study of the flow of the molten polymer through the extruder is a subject of research in graduate fluid mechanics. The flow is that of a non-Newtonian viscous fluid. One has to be concerned with thermomechanical coupling in the equation of state.) The molten polymer is forced through a die after which the polymer cools and solidifies as shown in Figure 10.2. The polymer expands radially and shrinks longitudinally. The die designer has to be concerned with these thermal changes in dimensions.
