A new constitutive theory for extrusion-extensional flow of anisotropic liquid crystalline polymer fluid

Shifang Han

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DOI: 10.4236/ns.2011.34040                

Abstract

A new continuum theory of the constitutive equation of co-rotational derivative type was developed by the author for anisotropic viscoelastic fluid－liquid crystalline (LC) polymers (S.F. Han, 2008, 2010) . This paper is a continuation of the recent publication [1] to study extrusion-extensional flow of the fluid. A new concept of simple anisotropic fluid is introduced. On the basis of anisotropic simple fluid, stress behavior is described by velocity gradient tensor F and spin tensor W instead of the velocity gradient tensor D in the classic Leslie?Ericksen continuum theory. A special form of the constitutive equation of the co-rotational type is established for the fluid. Using the special form of the constitutive equation in components a computational analytical theory of the extrusion-extensional flow is developed for the LC polymer liquids - anisotropic viscoelastic fluid. Application of the constitutive theory to the flow is successful in predicting bifurcation of elongational viscosity and contraction of extrudate for LC polymer liquids–anisotropic viscoelastic fluid. The contraction of extrudate of LC polymer liquids may be associated with the stored elastic energy conversion into that necessary for bifurcation of elongational viscosity in extrusion extensional flow of the fluid.

Keywords

Constitutive Equation of Co-Rotational Derivative Type; Simple Anisotropic Fluid; Liquid Crystalline Polymer; Extrusion-Extensional Flow; Bifurcation of Elongational Viscosity; Contraction of Extrudate of LC Polymer Liquids

Conflicts of Interest

The authors declare no conflicts of interest.

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