Ultrasound: A virtual instrument approach for monitoring of polymer melt variables

Non-invasive ultrasound measurements are not currently widely used, due to limitations in high temperature transducer technology and signal processing . These have been addressed in the ultrasound program in our laboratory, wh ere high frequency sampling using our own high temperature probes is now av ailable. The need for high frequency sampling of the ultrasound signal to r esolve measurements of transit time (and amplitude) to the required accurac y requires handling of large amounts of data, and in the case of actual pol ymer processing such as extrusion, data processing needs to be real time. A computer controlled system for the acquisition of such data is described h ere, with examples of the sensitivity of the measurements to a range of pol ymer melt process variables, including polymer composition and fillers, for extrusion and injection moulding processing.