3.1 General

In the course of blending polymers, the following systems can be formed: one-phase systems, two-phase (colloid) systems, or systems in a metastable state of transition from a one-phase into a two-phase system. The properties of polymer mixtures are determined to a great extent by the phase equilibrium in the system formed and their properties can be changed by controlling the processes of phase separation, which occur by two mechanisms: by nucleation and growth or by the spinodal mechanism.

Two-phase mixtures of polymers differ from classical colloid systems mainly by a transition layer that exists between the system components and is of special significance. The formation of such a layer in mixtures of linear polymers is governed by the kinetic factors of the retarded process of phase separation, by the collid-chemical mechanism of formation, or by the adsorption interaction as well as by the segmental solubility [103, 104]. In mixtures of crosslinked polymers its formation is governed also by the conditions of synthesis. Note also that in the thermodynamically nonequilibrium mixtures of polymers in the two-phase systems, the processes of segmental solubility usually have time to reach completion while the macromolecules do not move inside the high-viscosity medium, which ensures the stability of the structure and its mechanical properties [103].

The most promising method of obtaining polymeric materials is by the use of so-called hybrid binders. These constitute polymeric composite materials in which crosslinking indicates the heterogeneity of the distribution of the system components determined by thermodynamic incompatibility and...