Control of Curing by Chemical Reactivity or Diffusion

It can be shown that the specific diffusion control is not operative for the conventional mechanisms of curing of epoxy resins. The situation becomes somewhat complicated when high crosslinking densities are reached. 

In terms of the activated complex theory of reaction rate, the reaction between groups A and B can be written down as 

Curing of epoxy resins is a typical example where overall diffusion control can become operative. During curing, the glass transition temperature of the system increases and may reach or exceed the reaction temperature. This phenomenon is dealt with in several reviews of this volume, particularly in those by J. K. Gillham and E. F. Oleinik. 

While well above T, the dependence of the rate constant k on temperature is governed by the Arrhenius proportionality 

25-35 K (cf., e.g.. Refs. Therefore, during curing of some epoxy-curing agent 

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