Self-deceleration term

As an example, let us analyze mold filling with a model polyurethane formulation. Let the kinetics of curing be described by an equation with the self-deceleration term (as was discussed above). The following values of the parameters were used U = 49.1 kJ/mol ko = 3.8xl06 = 1.1 ATmax = 25.8°C where ATmax is the maximum expected increase in temperature for adiabatic curing. 

In their works,51"54 the self-similar fractal dimension dF>ss of the two-dimensional distribution of the pits was determined by the analysis of the digitized SEM images using the perimeter-area method. The value of dF>ss increased with increasing solution temperature,51 and it was inversely proportional to the pit shape parameter and the pit growth rate parameter.53 Keeping in mind that dr>ss is inversely proportional to the increment of the pit area density, these results can be accounted for in terms of the fact that the increment of the pit area density is more decelerated with rising solution temperature. 

The term of polymerization in bulk is utilized whenever the polymer formed is monomer-soluble the latter plays the role of solvent for a reaction medium that witnesses a very strong viscosity buildup as the yield increases the kinetics can then take an explosive mode, accelerated by the gel effect (or Trommsdotff effect). This phenomenon is actually a self-acceleration of the rate of polymerization (possibly until becoming explosive) followed by a strong deceleration of the process (see Figure 8.7). 

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