On-Line Ultrasonic Monitoring Method for Mixing Status of Polymer in the Screw Extrusion

As a response to the need of on-line monitoring for mixing status of polymer in screw extrusion, the ultrasonic wave propagation character during the PEEK buffer rod was studied. The cause of the trailing echoes when the ultrasonic wave was propagating in the PEEK buffer rod was analyzed, and the expressions for locating the position of trailing echoes was given. The influence of the buffer rod shape and cooling device on ultrasonic pulse echo was studied. The experimental results of different ratio between melted PP and CaCO3 showed that the attenuation of the ultrasonic wave propagation during the polymer could characterize the mixing status of polymer. The PEEK buffer rod could be used to monitor mixing status of polymer with melted temperature being lower than 160℃ during screw extrusion.