Pressure/Throughput Behavior of a Single-screw Plasticising Unit in Consideration of Wall Slippage

Abstract

The mathematical models so far available for describing the throughput behavior of plasticising extruders were developed with the assumption of a wall-adhering melt. There are, however, a series of plastic melts, and also elastomers, polymer suspensions, ceramic materials and food products that display wall slippage during processing. A mathematical model has been developed for this material behavior, which describes the flow behavior for the unidimensional, Newtonian, isothermal case.Apart from the development of the analytical model, the flow behavior of wall-slipping polymer melts was also analysed with the aid of finite element calculations (FEM). A comparison of the results for the pressure/throughput behavior shows that the calculation results tally very well for the two methods. It is thus possible to develop a procedure which makes it possible to describe the phenomenon of wall-slippage for the non-Newtonian, multi-dimensional, non-isothermal case.

Fundamentals of Global Modeling for Polymer Extrusion

“…Kalyon et al [241] as well as Malik et al [183] studied numerically co-rotating twin-screw extrusion with wall slippage at the barrel and screws. Potente and his co-workers, e.g., [236,[242][243][244][245][246] performed very extensive studies on modeling single-screw extrusion with slip effects, both analytically and numerically, by calculating the pressure/throughput and drive power behavior, as well as the melt temperature development in single-screw extrusion of wall-slipping polymers. Several studies were performed on modeling the flow of wall slipping polymers in the dies, e.g., by Ferras et al [247], Hatzikiriakos and Mitsoulis [248], and Gupta [249].…”

Simulation of Nonlinear Polyurethane Production in a Twin-Screw Extruder

“…(13) to (15), the mass, component, and heat balance equations can be written as indicated in Eqs. (11) to (16), where x in Eq.…”

“…[3][4][5][6][7][8][9][10] The different phenomena that determine the performance and operation of an extruder can be analyzed and better understood by using mathematical models. Potente et al [5,6,[11][12][13] and Flecke et al [14] have developed mathematical models for single and co-rotating extruders, which have been used to simulate several processes. Vergnes, Della Valle, and Delamare [15] proposed a global computational model for self-wiping co-rotating twin extruders, which have also been studied by several other research groups [16][17][18] .…”

Global Concept for Describing and Investigation of Wall Slip Effects in the Extrusion Process

“…The detailed derivation of the pressure/throughput-describing equations can be found in ref. [19] Figure 5 shows the basic correlations between the dimensionless pressure gradient and the dimensionless volume flow for the boundary condition of wall slippage.…”