A theoretical melting model for plasticating extruders

Abstract

A theoretical model for melting in plasticating extruders is described. Compared to previous models, this model introduces more accurate and less restrictive assumptions, adds a mass balance on the entire channel, and replaces certain approximate solutions by exact solutions. Flow of the solid bed is represented by a solid bed acceleration parameter, SBAP, which permits solid bed acceleration in a screw compression section. New experimental melting data for a variety of screw designs, polymers, and extruder sizes are presented and compared to the theoretical predictions. With the optimum SBAP, reasonably accurate model prediction of the melting profiles is observed for a wide variety of cases.

Melting of polymer blends in single-screw extrusion - an experimental study

“…Experimental melting studies were initiated by Maddock in the fifties, yielding a qualitative phenomenological understanding of the underlying mechanisms [1]. Based on this evidence, Tadmor developed the corresponding mathematical description [2], which in fact formed the basis of subsequent more sophisticated analyses [3][4][5][6][7][8][9]. In his model, Tadmor assumes that the solid pellets are compacted and form a continuous bed, which is separated from the inner barrel wall by a thin melt film.…”

Mathematical model of a single-screw plasticating extruder

“…Examples of such refinements are Lovegrove's two-dimensional solids conveying zone model [25], models with solid-bed break-up theory given by Donovan [26], other models for the MZ given by Mondvai et al [27], Shapiro and Pearson [18], Edmonson and Fenner [28] and Lindt's special model for PP [29], and Dyer's three-dimensional model [30] for the MCZ. In spite of the simplifications in our model is was successfully used to design different types of single-screw plasticating extruders working with PP, PA, PET as well as their pigment master batches in man-made fibre production.…”

CFD-Simulation der Kunststoffplastifizierung in einem Extruder mit durchgehend genutetem Zylinder und Barriereschnecke

“…Weitere Modifikationen und/oder Erweiterungen des Modells folgten u. a. durch Donovan [18], Edmondson und Fenner [19], Lindt [20][21][22], Syrjälä [23] und Potente [24,25]. Diesen Ansätzen ist gemein, dass sie sich ausschließlich für Prozesse im Einschneckenextruder nutzen lassen und stets auf die Betrachtung eines abgewickelten Schneckenganges angewiesen sind.…”