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Measurements on the planar extensional viscosity of bulk polymers: The inflation of a thin, rectangular polymer sheet
Author(s) -
Denson C. D.,
Crady D. L.
Publication year - 1974
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.1974.070180603
Subject(s) - extensional viscosity , materials science , polymer , extensional definition , viscosity , planar , rheology , newtonian fluid , composite material , strain rate , thermodynamics , physics , shear viscosity , geology , paleontology , computer graphics (images) , computer science , tectonics
An experimental study of the inflation of a thin rectangular polymer sheet has been conducted to determine whether this technique can be used to measure the planar extensional viscosity of bulk polymers. Viscosities were determined at various extensional strain rates using an undiluted polyisobutylene of high molecular weight. Measurements were also made on the dynamic shear viscosity using orthogonal geometry and compared with “normalized” values of the planar extensional viscosity assuming equivalency of $\sqrt {\Pi _e} $ the second invariant of the extensional strain rate tensor, and the frequency of rotation ω. Industrial fabrication operations where the planar extensional viscosity is expected to play a role include vacuum forming of large rectangular sheets whose length‐to‐width ratio is large and in injection molds having a center‐gated cavity.