Experimental Investigation of the Mixing Quality of High-Performance Screws
Sprache des Vortragstitels:
32nd International Conference of the POLYMER PROCESSING SOCIETY-July 25-29, 2016 LYON FRANCE
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Besides achieving high outputs, the melt quality is a crucial factor of efficient polymer processing using screw extruders. On the one hand, it is desired to achieve a homogenous melt, when it comes to the incorporation of fillers as carbon-black. On the other hand, melt temperature non-uniformities should be minimized, since melt temperature variation results in problems like non-uniform wall thickness and warpage.
Over the decades several high-performance single screw designs, as double or triple flighted screws, various barrier screws, multi-stage screws and screws with mixing elements have been developed with the goal of improving mixing and melting capabilities.
The aim of the present study is to assess and compare the mixing performance of different barrier and energy-transfer screws with respect to their throughput/pressure-behavior. The used extruder had a 34 length-to-diameter (L/D) ratio and a 35 mm barrel with a grooved inlet section. For the assessment of the temperature homogeneity a measurement cross was used. Furthermore, the study involved the gray-value analysis of extruded polymers mixed with carbon-black masterbatch for the evaluation of the transversal mixing behavior. The longitudinal mixing performance was investigated via fluorescence spectroscopy.