In-Line Measurement of the Polymer Melting Behavior in Single Screw Extruders
Existing experimental techniques designed to study melting behavior of polymers inside the screw extruder suffer from limited functions or tedious procedures. All the techniques developed in the past three decades are invasive, time consuming, difficult to implement and expensive. Their invasive nature affects friction characteristics and heat transfer, significantly influencing the outcome of measured parameters.
This thesis presents an in-line, non-invasive measuring technique that can accurately capture experimental data and images from inside the extruder through a small quartz window and a rigid boroscope at short response times using a highly instrumented 45 mm single screw extruder with built-in sensors. By sensing the difference in optical properties between the melt and the solid phase, the melting behavior of high density polyethylene was visualized and measured with this non-invasive technique. Using the system developed during this project we were able to observe and fully describe the mechanisms of melting in the plasticating zone of the single screw extruder. Through our experiments we were able to actually see and verify Tadmor and Pearson’s melting mechanisms. In addition, we were able to see, for the first time, a melt pool formation delay due to a solid bed saturation process. Besides presenting a new optical measurement system for polymer processing, a significant contribution of this research is the better understanding of polymer melting inside extruders and plastication zone of injection molding and blow molding machines. Since an extruder’s performance is coupled to the screw design, and the screw design depends on the polymer melting process. With this study, we are now, for the first time, able to accurately verify and modify the melting models, leading to improved screws in polymer processing.Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
Polymer Extrusion, Non-Invasive Optical Technique, Melting, Plasticating
Institute / chair: University of Wisconsin at Madison
Technical consultant for expert services: Prof. Dr. Tim A. Osswald
Publication year: 2002
Provider: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de
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