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An assessment of cogswell's method for measurement of extensional viscosity
Author(s) -
Kwag C.,
Vlachopoulos J.
Publication year - 1991
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.760311404
Subject(s) - viscometer , extensional viscosity , extensional definition , viscosity , materials science , thermodynamics , capillary action , mechanics , composite material , physics , geology , paleontology , shear viscosity , tectonics
Cogswell's method for measurement of extensional viscosity by determining the entry pressure loss in capillary viscometry is critically examined. Comparisons are made between extensional viscosity values introduced in finite element calculations as input data and predictions based on the calculated entry pressure losses for polymer melts. The calculated pressure losses are in good agreement with experimental data by Laun and Schuch. An equation proposed by Cogswell and another by Binding are used in the extensional viscosity comparisons. The slope of the extensional viscosity versus stretch rate is predicted rather well, but the calculations can shift the results above or below the true values.