Features of Temperature Transitions

For some systems a comparison of the properties of full and semi-IPNs has been made [227-229]. The main difference in dynamic mechanical properties consists in that the shift of temperature transitions in semi-IPNs is higher as compared with full IPNs. This effect was explained by the more complete phase separation in semi-IPNs as compared with full ones. 

A theoretical description of the glass transition behavior was developed for miscible IPNs and was based on the application of various equations con- 

For chemically cross-linked polymers, ex/sm 1. and the mobiUty of a chemically cross-linked segment Fx Fm, so that Fx/Fm 1, and the equation simplifies to 

An important problem in describing viscoelastic properties of IPNs consists of taking into account the properties of an interphase. There is great difficulty 

The same assumptions about the interphase layer led to a good agreement between theoretical and experimental dependencies of E on T with the value Vc taken constant for the model illustrated in Fig. 42b (additivity of moduli). On the other hand, no suitable Vc values could be foimd for all IPNs but 1 and 2. The ability to fit IPNs 1 and 2 by both two- and three-phase models is due to a low value of Vc. 

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