Practical Aspects of Behavior in the Terminal Zone

The practical significance of the terminal relaxation time r in several qualitative aspects of behavior has already been mentioned in connection with equation 7 for polymers of low molecular weight. The same considerations apply to polymers of high molecular weight, where t (or Ta, in the framework of the tube model) and the other two viscoelastic constants ijo and Jg which characterize the terminal zone are even more important in the processing and use of polymeric materials. Rough estimates of these quantities can sometimes be made from the equations in Section C3 above for practical purposes. 

The magnitudes of the terminal relaxation time (and the terminal retardation time, which differs from it only by a small factor) are also of considerable importance (c/. equation 7). For a polymer homogeneous with respect to molecular weight, Ti can be estimated from the viscosity by equation 7 if Af Me and by 

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