Rheological Study on Polypropylene/Cycloolefin Copolymer Blends |
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Authors: | Luca Fambri Jan Kolarik Emanuele Pasqualini Amabile Penati Alessandro Pegoretti |
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Affiliation: | 1. Department of Materials Engineering and Industrial Technologies, University of Trento, via Mesiano 77, 38050 Trento, Italy;2. Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovskeho nam 2, 16206 Prague 6, Czech Republic |
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Abstract: | Summary: Polypropylene, cycloolefin copolymer and their blends were characterized by means of melt flow analysis and capillary rheometry at temperatures between 190 and 230 °C in order to shed more light on COC fiber formation obtained in injection molding process. Melt viscosity and its activation energy as functions of blend composition show negative deviation from the expected additivity (Negative Deviating Blends). The COC/PP viscosity ratio increases with shear rate, but decreases with temperature. High temperature, low viscosity ratio and high shear rate seem to be favorable for fiber formation. Glass transition (from the reversible heat flow curve of modulated DSC) of dumbbell specimens produced by injection molding at 230 °C with COC minor component was 2–4 °C higher than that of grinded pellets obtained from mixing at 190 °C. |
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Keywords: | activation energy blending blends rheology |
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