Determination of the effect of pressure on viscosity at high shear rates by using an injection molding machine

摘要

The effect of pressure on rheological behavior of polymer melts is surely a significant phenomenon for polymer processing, and its determination has been the object of several studies which highlighted the difficulties in performing accurate measurements. Even more important is the determination of this effect at very high shear rates, which cannot easily be obtained by conventional rheometers. In this work, a slit rheometer was located at the nozzle of the injection molding machine to obtain rheological measurements by means of two pressure transducers. Pressure values were analyzed by an original method to evaluate the pressure coefficient and the viscosity at zero pressure. The zero pressure viscosity aligned with independent rheological measurements obtained in previous works. The effect of pressure on viscosity was described by means of a parameter whose values resulted to be in line with those obtained in previous works, although the highest shear rates explored in this work were at least one order of magnitude larger. (C) 2017 Wiley Periodicals, Inc.