Simulation of nonisothermal flow of melt during melting process of vibration-induced polymer extruder

摘要

A simplified 2D melt film model was established to simulate the nonisothermal melt flow during the melting process of the vibration-induced polymer extruder of which the screw can vibrate axially. Since polymer has time-dependent nonlinear viscoelastic characteristic with vibration force filed (VFF), a self-amended nonisothermal Maxwell constitutive equation that can reflect the relaxation time spectrum of polymer was adopted. Using the 2D melt film model, melt films of two kinds of thickness representing different melting stages were simulated to investigate the influence tendency of the same VFF on the different melting stage. Special flow patterns and temperature distribution of melt in the melt film between the driving wall and the solid/melt interface with various vibration force fields were systematically simulated. It is found out that within a certain range of vibration strength, the application of vibration can optimize the time-averaged shear-rate distribution, improve the utilization efficiency of energy, and promote melting process; and the thinner the melt film is, the more intense the nonlinear viscoelastic response becomes with the same VFF; moreover, there exists optimum vibration strength to make the melting process fastest, which is in accord with the visualization experimental results. (c) 2006 Wiley Periodicals, Inc.