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Melt viscosity—temperature dependence of some low density polyethylenes
Author(s) -
Mendelson R. A.
Publication year - 1965
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.760050107
Subject(s) - materials science , shear rate , thermodynamics , arrhenius equation , shear (geology) , shear stress , atmospheric temperature range , viscosity , superposition principle , constant (computer programming) , simple shear , shear modulus , pure shear , apparent viscosity , activation energy , composite material , chemistry , physics , quantum mechanics , computer science , programming language
Abstract The melt viscosities of three low density polyethylenes of widely varying melt indices were studied as a function of temperature over a broad range of shear rates and shear stresses. Apparent viscosities at constant shear stress could be fitted adequately to a simple Arrhenius equation over the entire temperature range studied. However, pronounced curvature of the log η a –1/T curves was observed for apparent viscosities at constant shear rate. The apparent activation energies for viscous flow at constant shear stress were found to decrease slowly with increasing shear stress and also to decrease with decreasing molecular weight. A temperature‐shear rate superposition was demonstrated to hold, and the shift factor dependence on temperature was determined.