Kinetic model of postpolymerization in the polymer-monomeric phase

Kinetic model of postpolymerization in the polymer-monomeric phase 

The types of postpolymerization kinetic curves shown can be qualitatively explained using the conception of the three reactive zones proposed earlier. Up to the moment when the polymerizing system is in the liquid monomer-polymeric phase (MPPh), namely up to the moment of conversion = 0 5, only a weak post-effect is observed. MPPh is characterized by low concentration of free radicals with a short life time. A visible post-effect is observed in the autoacceleration stage Po Py , that is, at the beginning of polymer-monomeric phase elimination and formation of the interface layer at the phase division boundary between MPPh and the polymer-monomeric phase PMPh, which are new reactive zones. In such reactive zones the translational and segmental mobilities of the macroradicals are sharply decreased and the life times are sharply increased. This explains the essential post-effect. 

Apart from the change in concentration of active radicals also the volume of reactive zones (or their volumetric parts (py, (p s and %) changes during the postpolymerization process. The volumetric part of MPPh (tpv) is decreased, the volumetric part of PMPh ( Ps) is increased and the volumetric part of the interface layer, taking into account the assumption that (p (Ps l- Ps), is increased at the beginning, reaches a maximum and then decreases. 

at starting conversions of the dark period Pq 0.5 a complete description of the postpolymerization kinetics needs to take into account the proceeding of the process in two reactive zones. This fact complicates the kinetic models describing postpolymerization kinetics and makes it very difficult to compare these models with experimental data. 

Therefore, we restrict ourselves to the analysis of the postpolymerization kinetics at the starting conversions of the dark period Pq 0.7. In this case, according to the previous analysis, we can assume with sufficient exactness Ps 1 that the postpolymerization process is concentrated manly in PMPh and is described by the last term in the equation 

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