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Stress relaxation after steady shearing: Applications and empirical representation
Author(s) -
Menefee Emory
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.1964.070080224
Subject(s) - shearing (physics) , rheology , extrapolation , shear rate , materials science , thermodynamics , newtonian fluid , shear (geology) , apparent viscosity , viscosity , mechanics , relaxation (psychology) , non newtonian fluid , composite material , mathematics , physics , mathematical analysis , psychology , social psychology
The measurement of stresss relaxation following steady‐state shearing is particularly useful in the terminal relaxation zone, where the rheological properties are molecular weight dependent. This paper contains a description of the method as applied to molten polymers, and an empirical function found to be useful for fitting the data. Three examples are given to demonstrate some direct and simple applications. First, the decrease of viscosity with increasing shear rate may be estimated by simply replotting the experimental data. Second, extrapolation of calculated viscosities to very high shear rates is shown to lead to a possible explanation for melt fracture. Third, the true Newtonian viscosity can be estimated from measurements conducted at a nonzero shear rate.