Polymerisation rates in copolymerisations

In copolymerisation, the average propagation rate coefficient (fcp) is given by the general equation  

In the case that also the penultimate unit influences the reactivity, the penultimate model applies. 

There can be eight different propagation steps distinguished in the penultimate unit model. The rate coefficients are defined as follows (example)  

In general the compositional data of a copolymerisation can be well described by the ultimate model. The kp data in copolymerisations, for example, obtained by the pulsed laser method (van Herk, 2000), are best described by the penultimate unit model. The description of the compositional data is less model sensitive. 

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