Width of Plateau Zone on Time Scale

The width of the plateau zone on the logarithmic time or frequency scale involves an arbitrary definition it could be taken as log where t is the terminal 

This would mean disappearance of the plateau zone with M/Me 1.4, a reasonable 

Experimentally the width of the plateau zone can probably be most clearly defined by the separation between the two peaks in the retardation spectrum as seen in Fig. 13-6. From data on polystyrenes, this appears to be equal to 3.4 log M/Mc when the molecular weight distribution is narrow. 

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