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Encyclopedia of Physical Science and Technology EN014C-660 July 28, 2001 17:14

Rheology of Polymeric Liquids

Chang Dae Han
University of Akron

I. Classification of Polymeric Liquids
II. Unusual Characteristics of Polymeric Liquid Flow
III. Definitions of Material Functions for Polymeric
Liquids
IV. Methods for Determining Rheological Properties
of Polymeric Liquids
V. Constitutive Equations for Predicting the
Rheological Properties of Polymeric Liquids
VI. Concluding Remarks

GLOSSARY one deals with, different branches of rheology may be
considered. For instance, polymer rheology deals with
Dynamic viscosity Real component of complex viscosity polymeric materials and biorheology deals with biological
in oscillatory shear flow. fluids (e.g., blood, mucus, and synovial fluids). Polymeric
Extrudate swell Swelling of extrudate upon exiting from materials cover a wide range of man-made materials, such
a die. as plastics, synthetic rubber, synthetic fiber, and many oth-
Loss modulus Imaginary component of the complex ers. These materials have very large molecules consisting
modulus. of many repeat units of small molecules. Because of the
Normal stress difference Difference in the two primary large size of the molecules, they exhibit unusual flow be-
normal stresses. havior under deformation. The study of the flow behavior
Normal stress effect Effect exhibiting the elasticity of of polymeric liquids is not only an intellectual challenge
polymeric liquid. to scientists, but also is of fundamental importance to an
Shear thinning behavior Decreasing trend of viscosity advancement of polymer technology.
with increasing shear rate.
Shear viscosity Viscosity in steady-state shear flow.
Storage modulus Real component of the complex I. CLASSIFICATION OF
modulus. POLYMERIC LIQUIDS

Inageneralsense,therearetwotypesofpolymericliquids:
RHEOLOGY is the science of the deformation and flow thermoplastics and thermosets. Thermoplastic polymeric
of matter. Therefore, depending on the type of matter liquids are thermally reversible in that, when solidified,

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