Kinetics and Polymerization Rate

The experimental determination of the chain transfer to polymer constant is difficult, as it does not necessarily result in a decrease of the MW of the polymer. Therefore, there is a large spread of values reported in the literature for this constant [6]. Since it involves hydrogen abstraction, the activation energy of chain transfer to polymer is relatively high (compared to propagation) and it is reported in the range of 9000 cal/mol in the case of ethylene 

Recent studies convincingly proved the existence of midchain radicals (MCRs) and the secondary reactions that are responsible for the formation of MCRs during the polymerization process [9]. For instance, the polymerization of butyl acrylate (BA), and in general of the acrylate monomer family, proceeds with the presence of two radicals a chain-end (secondary) radical and an MCR (tertiary and significantly 

The MCRs can also be formed by intermolecular chain transfer to polymer (leading to long-chain branches), but its contribution is small. 

In its simplest and essential form, the mechanism of FRP involves the steps of initiation (radical generation), propagation, and bimolecular termination. The corresponding reaction rates for the three steps are denoted by R, R, and R, respectively. To derive a rate expression, for the sake of generality, the simplified mechanism and expressions in columns 2 and 3 of Table 4.5 are considered first later a more detailed mechanism (column 4 of Table 4.5), specific for chemical initiation and involving termination by disproportionation and combination, is analyzed. 

In FRP, the progress of the reaction is measured in terms of conversion of monomer into polymer (this is different 

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