Thermal load in the processing of thermoplastics

By manipulation of residence time and temperature distributions along a streamline, a reduced residence time may be formed which is a quantitative measure of the thermal load to which the material being processed is subjected in any part of the process. This method is applied in two examples. In the metering zone of a single screw extruder the highest thermal load is found at 2/3 of the channel height. For a case of pipe cool ing it is shown that a much higher extrusion temperature is possible without increasing the danger of degradation by the addition of an internal cooling system to the conventional sizing method.