The reliability of numerical simulations of the injection molding process depends mainly on the theological characteristics of polymers. The rheological characterization of a polymer for injection molding is commonly carried out by a capillary rheometer. However, in this method the measurement is carried out on a sample of unprocessed polymer, neglecting the influence of the plastication phase. This influence is demonstrated in the first part of the paper by comparing the theological characterizations of a polycarbonate both in the virgin and processed state. To improve the accuracy of theological data by rejecting these simplifications, a laboratory test method has been developed for the physical simulation of polymers theology under industrial process conditions. The method is based on an in-line slit-die rheometer which has been mounted as a mold on an injection molding machine. By means of this test it is possible to relate a polymer viscosity not only to its temperature and shear rate but also to those parameters that characterize the plastication process: screw rotation speed, residence time, temperature and geometry of the system.
Development of a test method for the rheological characterization of polymers under the injection molding process conditions
BARIANI, PAOLO FRANCESCO;LUCCHETTA, GIOVANNI
2007
Abstract
The reliability of numerical simulations of the injection molding process depends mainly on the theological characteristics of polymers. The rheological characterization of a polymer for injection molding is commonly carried out by a capillary rheometer. However, in this method the measurement is carried out on a sample of unprocessed polymer, neglecting the influence of the plastication phase. This influence is demonstrated in the first part of the paper by comparing the theological characterizations of a polycarbonate both in the virgin and processed state. To improve the accuracy of theological data by rejecting these simplifications, a laboratory test method has been developed for the physical simulation of polymers theology under industrial process conditions. The method is based on an in-line slit-die rheometer which has been mounted as a mold on an injection molding machine. By means of this test it is possible to relate a polymer viscosity not only to its temperature and shear rate but also to those parameters that characterize the plastication process: screw rotation speed, residence time, temperature and geometry of the system.Pubblicazioni consigliate
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