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Injection molding of semicrystalline polymers. I. Material characterization
Author(s) -
Isayev A. I.,
Chan T. W.,
Shimojo K.,
Gmerek M.
Publication year - 1995
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1995.070550518
Subject(s) - materials science , rheometer , shear rate , composite material , birefringence , crystallization , crystallinity , shear (geology) , extrusion , polypropylene , rheology , thermodynamics , optics , physics
Various material data for an isotactic polypropylene were acquired for the simulation of the injection molding of this material. Viscosity as a function of shear rate and temperature was measured using a capillary rheometer at high shear rates and a cone‐and‐plate rheometer at low shear rates. Heat‐flow properties, characterizing kinetics and induction time of quiescent crystallization, were obtained from DSC measurements. Material data characterizing shear‐induced crystallization were obtained from extrusion experiments through a slit die with subsequent quenching of the material in the die after various rest times. The thickness of the shear‐induced crystallization layer was measured along with the birefringence in this layer. A model of shear‐induced crystallization developed by Janeschitz‐Kriegl and co‐workers was used to fit the kinetic data. Thus, kinetic parameters such as the limiting shear rate below which no shear‐induced crystallization can occur and the characteristic time for the relaxation of birefringence were obtained. © 1995 John Wiley & Sons, Inc.