Viscosity Models of Polymer Flow in PVC Extrusion Process

D. M. Jahin

Department of Mechanical and Materials Engineering, University Kebangsaan Malaysia, Selangor Darul Ehsan, Malaysia, *Email: jahin@mynet.com

ABSTRACT: An empirical model to decide the viscosities of thermoplastic polymers in the extrusion process. The viscosity is calculated from the screw rotation speed, melt temperature, geometric dimensions of the extruder and material constants, which were experimentally determined. Polyvinyl clorur (PVC) was used in this study to test the effectiveness of the model. Comparing the calculated results, it was found that the viscosities obtained with the present model are in agreement with those obtained by using in line rheometer. The extrusion of PVC polymers with a two layer vented screw has been studied. Experimentally, the pressures and temperatures were measured at the end of each layer, for different processing conditions (screw speed, die geometry etc.). Screw pulling experiments have allowed to observe the partially filling of the different screw sections. The variation of the pressure and the temperature all along the screw, as well as the filling length of the second layer are then obtained. The theoretical results are in good agreement with the experimental measurements.

Keywords:Viscosity model; PVC; Extrusion process.