Monomer Reactivities and Chain Initiation

Monomer reactivities have been found to be essentially independent of the free-radical process used (e g., bulk, emulsion) bnt ean be affeeted tremraidonsly for the same pair of monomers if the chain carrier is ehanged. 

This illustration merely accentuates the need to answer the questions, why do the values of r and Zj differ so widely and why does r for a given monomer change when the comonomer is changed  

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