ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
A kinetic network model has been developed to describe the nonlinear rheological behavior of entangled polymer solutions and melts in either steady-state or transient flows. This model is based on the concept of flow-induced structure variation, controlled by the simultaneous existence of entanglement loss and regeneration. When steady-state is attained, both processes occur at the same rate and the structural state (entanglement density) of the fluid remains constant with time. Under transient flow conditions, the fluid structure becomes time-dependent as a result of unequal rates of the two competing processes affecting entanglement density. The viscoelastic response of the fluid is, in turn, influenced by the varying structural state. This is incorporated into the model through the use of structure-dependent coefficients in the contravariant Maxwell constitutive equation for entanglement stress. Model predictions are generated for a number of transient flow programs, including the stress growth and relaxation, interrupted flow, sudden change in shear rate, and nonlinear creep experiments. Comparison with literature data supports not only the qualitative success but also the quantitative ability of this model.
Additional Material:
14 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760211109
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