Two Dimensional Description of Pressure-Throughput Behaviour of Newtonian Materials Considering Wall Slippage Effects

摘要

The description of pressure-throughput behaviour of wall adhering melts in plastifying machines has been issued in a number of publications,e.g.[1 to 4] in details.Nevertheless there are a variety of polymer melts as well as elastomers,polymer suspensions,ceramic materials and food stuff,which do not behave wall adhering in the course of manufacturing.The theoretical discussion of the pressure-throughput behaviour has not sufficiently been described up to now.Worth's [5] case studies include the isothermal one-dimensional flow of a Newtonian medium in an unwinded screw channel.He assumed that after exceeding a critical shear rate the slipping process starts on the barrel wall only-but not on channel wall and screw root surface.Mennig,[6 to 9] took up this statement again and assuming a shear rate on the barrel wall as well as on the screw root surface he derived simple relations for the radial velocity profile from it.Lawal and Kalyon [10 to 12] have developed an analytical model that describes the behaviour of visco-plas-tic liquids in flat channels for different quotients of wall slippage,which are derived from the wall slippage quotients on screw root surface and on barrel wall.A mathematical model describing the flow behaviour for the two-dimensional Newtonian,isothermal case has been developed for wall slipping materials in order to describe the pressure-throughput behaviour multi-dimensionally.In addition to the development of the analytical calculating model the flow behaviour of wall slipping polymer melts has been analysed by using the finite-element-calculation (FEM).Comparison of the pressure-throughput behaviour results show a high degree of conformity in the calculation results.