Stress Tensor After a Step Strain

In the original Doi-Edwards model, retraction is assumed to occur infinitely fast. The stress tensor is then given by the elastic, or Brownian, stress for rigid rods [see Eq. (6-36)]  

Although the expression for the stress tensor in the Doi-Edwards model is the same as that of the temporary network model, except for the coefficient [see Eq. (3-13)], 

The factor of 5 is introduced into the definition of Q so that Q equals the linear viscoelastic strain, y, when the strain is small. G% — vk T is then the plateau modulus. When the 

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