Viscosity Control On Extruders by Means of Ultrasonic Devices.

This is a report on research program in which ultrasonic techniques have been used to measure ″dynamic viscosity″ of polymer melts on extruders in the course of extrusion. The dynamic viscosity is determined by measuring the sonic speed and the absorption coefficient. It could be proved that a control of the sonic speed or the propagation rate of sound is a useful basis for controlling the flow properties of the melt during the processing cycle. Basically, the method is suitable both for stationary and unstationary processes (extrusion or injection molding).