Diffusion controlled reactions in polymer degradation

Diffusion processes often control the rate of elementary steps in polymerization processes. It is thus not surprising that diffusion plays an important role in the degradation of bulk polymers or even of polymer solutions. 

This aspect of the kinetics of polymer degradation has been surveyed by Jellinek and Luh [22]. Three types of diffusion controlled reaction have been discussed. 

In this case, the concentration of the macroradicals is not necessarily stationary and the rate of monomer formation can be shown to be 

Both equations are identical if the tanh term tends to one. Numerical evaluation has shown that this is usually the case. 

The zip length and the total number of caged radicals have now to be obtained. If the steady-state method can be applied to radicals in the cage, then 

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