Temperature Dependence of Rate and Chain Length

We may assume that the temperature dependence of the individual rate constants in each of the steps of the reaction are given by the Arrhenius expression  

Similar treatment of Equation 9.27a, with the assumption that is independent of temperature, results in  

Example 9.2 For a typical free-radical addition reaction, Ep — E,/2 = 5 kcal/mol and E = 30kcal/mol. Estimate the changes in Vp and x for a typical homogeneous, free-radical addition polymerization when the temperature is raised from 60 to 70 °C. 

The effective activation energy for is —lOkcal/mol. With Equation 9.31, we get 

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