Nonlinear regime—tube dilation

The nonlinearity in the kinetic equation becomes important if the external perturbation is large. In this case precise mathematical analysis becomes quite difficult. A convenient approximation is to replace r by the average A- 

This can be handled much more easily than eqn (9.3Q (see refs 2 and 10). Though the approximation (9.41) is crude, it takes into account the 

The tube dilation may be seen in, for example, the relaxation of birefringence from the highly oriented state the initial relaxation rate is larger than the final one. A theoretical analysis of this effect has been done in ref. 2 

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