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Extrusion of polypropylene. Part I: Melt rheology
Author(s) -
Brandao J.,
Spieth E.,
Lekakou C.
Publication year - 1996
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.10383
Subject(s) - die swell , rheology , polypropylene , materials science , swell , extrusion , rheometer , composite material , plastics extrusion , shear rate , extrusion moulding , viscosity , thermodynamics , physics
This paper considers the rheology of extruded polypropylene regarding melt flow index, shear viscosity, and die swell. Two grades of polypropylene are studied with differences in the molecular weight and rheology. An Instron capillary rheometer is used for the measurement of viscosity and die swell. A range of shear rates and temperatures is covered in these measurements. Die swell is also measured in polypropylene extruded through a commercial single screw extruder where the effect of varying conditions of cooling and annealing on die swell are tested. A detailed theoretical analysis is carried out for the die swell. Analytical expressions are employed for the description of viscosity and die swell with empirical constants which are determined from the experimental data.