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Scale‐up rules for mixing in a non‐intermeshing twin‐screw extruder
Author(s) -
Bigio D.,
Wang K.
Publication year - 1996
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.10684
Subject(s) - materials science , mixing (physics) , distributive property , scale (ratio) , extrusion , flow (mathematics) , mechanical engineering , mechanics , plastics extrusion , drag , scale up , engineering drawing , composite material , mathematics , classical mechanics , engineering , physics , quantum mechanics , pure mathematics
Various scale‐up rules and theories have been presented for extrusion, including both single‐ and twin‐screw extruders. Until now, however, most of these theories have concerned fully‐filled channels, not only for twin screw extruders of the co‐rotating fully intermeshing type (COTSE) or non‐intermeshing counter‐rotating type (NITSE), but single screw extruders as well. As the demand for distributive mixing and devolatilization devices increases, more and more nonintermeshing twin screw extruders with regions of partially‐filled channels are being used. Therefore, developing scale‐up rules for such screw extruders is imperative. In this paper, scale‐up rules are developed, theoretically and experimentally, by examining the relationship between distributive mixing and important flow parameters. Two partially‐filled NITSE's, with screw diameters of 0.8 and 2 inches, have been studied by using a flow visualization technique entailing a dye tracer to study the effects of distributive mixing by varying such parameters as: percentage of drag flow, screw stagger, and screw velocity. Qualitative evaluation of the spread of the dye with the number of screw revolutions was obtained from videotape of the experiments. Factorial experimental design method has been applied for evaluating these results. Finally, new scale‐up rules were developed and compared with rules in the literature.