Abstract
In single-screw extrusion the simulation of the plasticizing process by means of software tools becomes more and more important. These programs need mathematical models that have to be improved continuously to simulate the process values realistically. A two-part article presents an analytical approach to calculate the pressure/throughput and drive power behaviour of wall-slipping polymers in the melting section of single-screw plasticizing units. The investigations that are conducted are based on the notion commonly found in the literature of a melt film forming between the barrel and a compact solid bed, with the simultaneous development of a melt pool. As boundary condition for describing the wall slippage, a critical shear stress, as of which a slippage process commences, and also a slippage-velocity-dependent shear stress is assumed. In this first part of the publication, the investigations focus on the processes that take place in the melt film. A new model is developed for describing the process behaviour in this area.
References
Archer, L. A.: Chapter 4 Wall Slip: Measurement and Modeling Issues, in Polymer Processing Instabilities, Hatzikiriakos, S. G., Migler, K. B. (Eds.), Marcel Dekker, New York(2005).Search in Google Scholar
Brochard, F., de Gennes, P. G., Shear-Dependent Slippage at a Polymer/Solid Interface, Langmuir, 12, 3033–3037(1992).10.1021/la00048a030Search in Google Scholar
Dekker, J., „Verbesserte Schneckenkonstruktion für das Extrudieren von Polypropylen“, Kunststoffe66, 130–135(1976).Search in Google Scholar
Grünschloß, E.: Der Einschneckenextruder-Grundlagen und Systemoptimierung, VDI-Verlag, Düsseldorf(2001).Search in Google Scholar
Hatzikiriakos, S. G.: A Slip Model for Linear Polymers Based on Adhesive Failure, Int. Polym. Proc.8, 135–142(1993).Search in Google Scholar
Hatzikiriakos, S. G., J. M.Dealy, Wall Slip of Molten High Density Polyethylenes. II. Capillary Rheometer Studies, J. Rheol.36, 703–741(1992).10.1122/1.550313Search in Google Scholar
Jungemann, J., „Verbesserte Modellbildung am Glattrohr-Plastifizierextruder“, Thesis KTP-Institut für Kunststofftechnik, University of Paderborn(1999).Search in Google Scholar
Klenk, P., „Plastifiziermodelle für die Verarbeitung benetzender und nicht benetzender Thermoplaste auf Einschnecken-Extrudern“, Rheol. Acta7, 75–78(1968).10.1007/BF01970317Search in Google Scholar
Kurte-Jardin, M., „Einfluss des Wandgleitens auf das Prozessverhalten wandgleitender Kunststoffe bei der Verarbeitung mit Einschneckenmaschinen“, Thesis KTP-Institut für Kunststofftechnik, University of Paderborn(2007).Search in Google Scholar
Lindt, J. T., Pressure Development in the Melting Zone of a Single-Screw Extruder, Polym. Eng. Sci., 16, 284–291(1976).10.1002/pen.760160411Search in Google Scholar
Lindt, J. T., A Dynamic Melting Model for a Single-Screw Extruder, Polym. Eng. Sci., 21, 1162–1166(1981).10.1002/pen.760211708Search in Google Scholar
Maddock, B. H., A Visual Analysis of Flow and Mixing in Extruder Screws, SPE ANTEC Tech. Papers, 15, 383–389(1959).Search in Google Scholar
Meijer, H. E. H., Verbraak, C. P. J. M., Modeling of Extrusion with Slip Boundary Conditions, Polym. Eng. Sci., 28, 758–772(1988).10.1002/pen.760281108Search in Google Scholar
Mennig, G., „Grundlagen der Extrusion wandgleitender Substanzen“, Kunststoffe70, 254–257(1980).Search in Google Scholar
Mennig, G., „Geschwindigkeitsverteilung im Schneckenkanal für wandgleitende Substanzen“, Kunststoffe74, 296–298(1984).Search in Google Scholar
Mooney, M., Explicit Formulas for Slip and Fluidity, J. Rheol., 2, 210–222(1931).10.1122/1.2116364Search in Google Scholar
Obermann, C., „Theoretische und experimentelle Untersuchungen zum Durchsatz- und Leistungsverhalten von Glattrohr-Plastifiziereinheiten“, Thesis KTP-Institut für Kunststofftechnik, University of Paderborn(2000).Search in Google Scholar
Pérez-González, J., De Vargas, L.: Quantification of the Slip Phenomenon and the Effect of Shear Thinning in the Capillary Flow of Linear Polyethylenes, Polym. Eng. Sci.42, 1231–1237(2002).Search in Google Scholar
Potente, H., Kurte-Jardin, M., „Aus der Forschung: Einfluss des Wandgleitens auf das Prozessverhalten wandgleitender Kunststoffe, Teil 2“, Extrusion11, 92–97(2006).Search in Google Scholar
Potente, H., et al., Two Dimensional Description of Pressure-Throughput Behaviour of Newtonian Materials Considering Wall Slippage Effects, Int. Polym. Proc., 20, 212–221(2005).Search in Google Scholar
Potente, H., Obermann, C., Screw Drive Power of Single Screw Plasticating Units With Smooth Barrels, Int. Polym. Proc., 14, 21–27(1999).Search in Google Scholar
Potente, H., Ridder, H., Pressure/Throughput Behaviour of a Single-Screw Plasticising Unit in Consideration of Wall Slippage, Int. Polym. Proc., 17, 102–107(2002).Search in Google Scholar
Potente, H., et al., Description of the Pressure/Throughput Behaviour of a Single-screw Plasticating Unit in Consideration of Wall Slippage Effects for Non-Newtonian Material and 1-D Flow, Int. Polym. Proc., 21, 272–282(2006).Search in Google Scholar
Ramamurthy, J., Wall Slip in Viscous Fluids and Influence of Materials of Construction, J. Rheol., 30, 337–357(1986).10.1122/1.549852Search in Google Scholar
Schofield, R. K., Scott Blair, G. W., Relationship between Viscosity, Elasticity and Plastic Strength of Soft Materials as Illustrated by Some Mechanical Tests, Proc. Roy. Soc. A, 138, 707–718(1932).10.1098/rspa.1932.0211Search in Google Scholar
Wiegreffe, S., Badura, R., Influence of the Wall Slip Behaviour of Rubber Compound on their Processability with Pin Barrel Extruders, Kautschuk Gummi Kunststoffe, 44, 922–927(1991).Search in Google Scholar
Worth, R. A., et al., Wall Slip and Its Implications in the Design of Single Screw Melt-Fed Extruders, Polym. Eng. Sci., 17, 257–265(1977).10.1002/pen.760170409Search in Google Scholar
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