A Note on Termination Rate Constant

Researchers in the United Kingdom and the United States who pioneered much of our knowledge of free-radical polymerizations used different conventions for termination rate constants. All United States texts and data compilations adhere to the American system while United Kingdom texts rely on the British method. Though the convention is seldom explicitly specified, it can be usually inferred from the particular context. 

On the other hand, the American convention, which is followed in this text, uses the following definitions  

The rate constants quoted according to the American convention will thus be exactly half those measured by the British system. However, the same conclusions about polymerization rates are reached when either usage is adopted because a compensatory factor of 2 is present in the kinetic equations that use American rate constants and not in those corresponding to the British system. Hence, each convention is unobjectionable if used consistently but the two cannot be mixed. 

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