The Constitutive Equation for an Isothermal Solution of Rouse Chains

4 The Constitutive Equation for an Isothermal Solution of Rouse Chains 

For an isothermal system, by combining Eq. (14.13) with Eq. (13.9) the -tensors can be eliminated and a constitutive equation for the stress tensor is obtained, through terms of second order AEFIRSXC ToVn,  

This is in conflict with the expenmental data, which show a strong shear-rate dependence. Also, this model leads to an infinite elongational viscosity at a finite 

We begin by writing Eq. (13.4) for Hookean dumbbells, multiplying this equation by — HQQ, and integrating over Q Then, when Eqs. (14.10) and (14.16), appropriately simplified for N = 2 and isothermal systems, are used, we find that - through terms of third order ADEFIXToV ,  

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