Reaction Kinetics and Properties of Evolved Phases

The kinetic effects influence not only the onset of the phase separation but also the composition and the ratio of evolved phases as well. It was shown that it is possible to evaluate the ratio of phases and their composition from the shifts of glass transition temperatures of each phase with respect to the pure component prevailing in this phase. Because of this, the elucidation of the kinetics of the transitions in evolved phases is of great importance for im-derstanding of the interrelation between the reaction conditions and phase separation proceeding in the systems. 

The kinetics of the formation of these systems was studied [202] for the PU/PBMA IPNs. As distinct from the preceding results, in this work the phase separation resulting from kinetic changes was estimated by the glass transition temperatures of two evolved phases, which characterize their composition and hence the conditions of phase separation. Table 14 shows some parameters of semi-IPN PU/PBMA 85 15 mass % obtained by introduction of Hnear PBMA into the reaction mixtme. The main criterion of phase separation in this work is the shift of glass transition temperature of the two evolved phases, each of which is enriched by one of the components. 

The glass transition temperatures of the evolved phases depend on the way PBMA was introduced I is the commercial PBMA introduced into 

the most typical feature of the kinetics of IPN formation is a superposition of chemical and physical processes, which distinguishes these systems from all other polymeric materials. The analysis of the data concerning 

If one of the networks is formed much faster than the other, its formation proceeds in the hquid medium of the second network components, hi this case the phase separation may be rather complete and be frustrated. The evolution of the swollen phase of the first network in the hquid medium is possible. The second network is formed later and, as a result, a system with rather high segregation degree arises. 

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