The Kinetics of Catalyzed Polyesterifications

Further evidence supporting Flory s assumption and analysis came from studies of the same reaction, catalyzed by the addi- 

Again assuming equal amounts of reacting functional groups, we get Equation 4-18. 

FIGURE 4-H Graph of 1/(1 - p) versus f [redrawn from the data of P. J. Flory, JACS, 61, 3334 (1939)]. 

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The derivation (Sec. 2-2b) of the kinetics of catalyzed polyesterification assumes that the catalyzed reaction is much faster than the uncatalyzed reaction, that is, k 3> k. This assumption is usually valid and therefore one can ignore the contribution by the uncatalyzed polyesterification to the total polymerization rate. For example, k is close to two orders of magnitude larger than k for a typical polyesterification. For the atypical situation where k is not negligible relative to k , the kinetic expression for [M] or Xn as a function of reaction time must be derived [Hamann et al., 1968] starting with a statement of the polymerization rate as the sum of the rates of the catalyzed and uncatalyzed polymerizations ... 

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