The Measurement Methods Of Polymer Melt Density Based On Ultrasonic Response Characteristics In High Temperature And Pressure

In recent years, with the development of polymer synthesis technologyand forming technology, the functional polymer materials are widely used invarious fields of national economic. In polymer processing process, theuniformity and stability of polymer melt density has a very important impacton the quality of the final products. Achieving the measurement of meltdensity fast and accurately is an important guarantee of product qualityprecision. Polymer molding process is a complex plastics molding processinvolving physical and chemical changes. Conventional detection methods cannot achieve the measurement of the melt density. Ultrasonic is a mechanicalwave which can transmit in the continuous and elastic medium. Ultrasound isnon-destructive, sensitive, non-invasive, rapid-response to physical parametersof the propagation medium. By studying the reaction of ultrasound used inhigh temperature and high pressure, we can use the ultrasound technology to achieve the online measurement of melt density in polymer processing. Themain contents are these:1.The structure of buffer rod used in high temperature and pressure is studied.We are utilizing the ultrasonic propagation characteristics to explain why thetrailing pulse will be generated. In order to restrain trailing pulses, we candamage the conditions on which the trailing pulses exist by changing thesurface structure of buffer rod.2.We are utilizing the heat transfer theory to design the best length of thecooling section of buffer rod which can make the ultrasonic probe worknormally.3.The experimental measurement methods of ultrasonic melt density is studied,based on the PVT principle of the polymer melt,we can achieve themeasurements of ultrasonic velocity and the polymer melt density in differentprocess variables.4. Soft methods of measurement of the density of the polymer melt is studied,according to the factors which can influence the polymer melt density,we areusing the neural network technology to build the measurement’s model ofmelt density with different input variables. we can establish the bestmeasurement’s model by comparing with different model’s predictionaccuracy.