Modeling of Polymer Devolatilization in a Multi-vent Screw Extruder
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N. H. Wang
Abstract
A model for representing polymer devolatilization behavior in a screw extruder with multi-vent sections has been proposed. In this model, an overall film-interface geometry factor (OFIGF) comprised of several local film-interface geometry factors (LFIGF) is used as a measure for the devolatilizing performance of a screw extruder. Moreover, the OFIGF is related to screw geometries and open angles of open areas in vent sections, and dependent on the degree of filling or the flowrate of the fluid and the screw speed. An intermeshing co-rotation twin-screw extruder popularly used was taken as an example to discuss the effect of the OFIGF on its devolatilizing performance. For this purpose, a solution of how to calculate the local film-interface areas and their exposure time in a venthole unfitted zone (VUfZ) and a venthole fitted zone (VFZ) with an open area was presented. Furthermore, several interesting results about how the OFIGF is affected by flowrate, screw speed, lead, and number of tips were predicted and discussed. The results suggested that the devolatilizing performance of the VFZ is lower than that of the VUfZ due to decrease in the surface renewal effect there, and a plot of ln {(wout – w*)/(win – w*)} against (N1/2/Q) in generally used flowrate and screw speed ranges for a given screw geometry does not strictly satisfy a linear relationship due to the filling-degree dependence of the OFIGF.
© 1995, Carl Hanser Verlag, Munich
Artikel in diesem Heft
- Contents
- Contents
- Editorial
- Sixteenth in a Series: Berstorff: Pioneer of Calenders and Screw Extruders
- Screw Extrusion/Continuous Mixing
- A Throughput Model for Grooved Bush Extruders
- Modeling of Polymer Devolatilization in a Multi-vent Screw Extruder
- Models of Flow and Experimental Studies on a Modular List/Buss Kokneter
- A Study of Distributive Mixing in Counterrotating Twin Screw Extruders
- Stress Controlled Simultaneous On-line Measurements of Viscosity, Flow Exponent, and Melt Index
- Film
- Microporous Film, Made from β-Crystalline Phase Polypropylene
- Analyses of Bowing Phenomena in Successive Transverse Stretching and Thermosetting Process for Biaxially Oriented Film
- Molding
- Comparative Wide-angle X-ray and Microscopical Studies on the Layered Structure in Injection Molded Polypropylene Disks
- Cooling Process Window Development for Injection Molding
- Modeling and Finite Element Analysis of Flow in SMC Compression Molding
- Reactive Processing
- Tool Heat Transfer Analysis in Resin Transfer Molding
Artikel in diesem Heft
- Contents
- Contents
- Editorial
- Sixteenth in a Series: Berstorff: Pioneer of Calenders and Screw Extruders
- Screw Extrusion/Continuous Mixing
- A Throughput Model for Grooved Bush Extruders
- Modeling of Polymer Devolatilization in a Multi-vent Screw Extruder
- Models of Flow and Experimental Studies on a Modular List/Buss Kokneter
- A Study of Distributive Mixing in Counterrotating Twin Screw Extruders
- Stress Controlled Simultaneous On-line Measurements of Viscosity, Flow Exponent, and Melt Index
- Film
- Microporous Film, Made from β-Crystalline Phase Polypropylene
- Analyses of Bowing Phenomena in Successive Transverse Stretching and Thermosetting Process for Biaxially Oriented Film
- Molding
- Comparative Wide-angle X-ray and Microscopical Studies on the Layered Structure in Injection Molded Polypropylene Disks
- Cooling Process Window Development for Injection Molding
- Modeling and Finite Element Analysis of Flow in SMC Compression Molding
- Reactive Processing
- Tool Heat Transfer Analysis in Resin Transfer Molding
