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Elongational viscosity of polymer melts: A lubricated skin‐core flow approach
Author(s) -
Pendse Ajit V.,
Collier John R.
Publication year - 1996
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/(sici)1097-4628(19960222)59:8<1305::aid-app14>3.0.co;2-4
Subject(s) - rheometer , materials science , composite material , polymer , viscosity , capillary action , polystyrene , extensional viscosity , rheology , extrusion , core (optical fiber) , die (integrated circuit) , polymer chemistry , nanotechnology , shear viscosity
Previous work by this research group has shown that the use of a lubricated skin/core flow of polymer melts and a hyperbolic converging die results in an essentially pure elongational flow at a constant elongational strain rate in the core. The previous work was carried out on a laboratory‐scale coextrusion system in a planar slit die; tracer particles and an image analysis system were used to confirm the predicted behavior. In this work, the technique was implemented first on the coextruder assembly, as a planar elongational rheometer, and then on a commercial capillary rheometer, as a uniaxial elongational rheometer for polymer melts. The later is achieved by replacing the standard capillary die with a hyperbolic axisymmetric die. A two‐laycred billet is prepared for placement in the rheometer barrel by completely encapsulating the core polymer (the polymer to be analyzed) with a low‐viscosity polyethylene skin. Commercial grades of polypropylenes, syndiotactic polystyrene, and nylon‐66 were analyzed using this technique. Elongational viscosity at high extensional rates can be determined with this method; values in excess of 500 s −1 have already been achieved. © 1996 John Wiley & Sons, Inc.