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Effect of homogeneity on viscosity in capillary extrusion of polyethylene
Author(s) -
Heitmiller R. F.,
Naar R. Z.,
Zabusky H. H.
Publication year - 1964
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.1964.070080226
Subject(s) - materials science , laminar flow , viscosity index , polyethylene , extrusion , composite material , capillary action , reduced viscosity , viscosity , melt flow index , homogenization (climate) , viscometer , apparent viscosity , homogeneity (statistics) , homogeneous , shear (geology) , polymer , thermodynamics , copolymer , scanning electron microscope , mathematics , biodiversity , ecology , base oil , physics , biology , statistics
Abstract The change in melt flow properties, as determined by melt index measurement, as a function of shear history, has been measured for linear polyethylene. It is shown that a drop in melt index occurs when a polymer sample which has had no previous shear history is melted and subjected to shear mixing. This fact is attributed to a molecular homogenization of a previously unmixed blend. An analytical model of the laminar flow in a pipe of concentric adjacent fluids with different viscosities is presented. The model indicates that the effective viscosity of this non‐homogeneous system is much lower than the viscosity of fan intimate blend of the same viscosity of an intimate blend of the same viscosity fluids.