Phase separation reactive blending

This section focuses on the modification of epoxy resins by blending with acrylonitrile butadiene (nitrile) resins. These are true alloyed blends since the nitrile rubber usually contains no groups that are normally reactive with epoxy groups. The nitrile molecules and the epoxy molecules intermingle as a blend to provide a single-phase alloy. If a large elastomer concentration is used, no phase separation will occur to form precipitates. 

The physical blend dissolves and separates very fast. The reactive blended products did not show a phase separation. After these pre-examinations several blends shown in Table 8 were separated quantitatively. This proved to be very difficult and time-consuming work. 

The definition of compatibility has been differentiated from miscibility since it is concerned with phase-separated polymers and is approached through the attainment of optimum properties for the blend (Bonner and Hope, 1993). Two of the main technologies used to achieve it are the addition of a third component (as discussed above) and reactive blending. The target in using a compatibilizer is the control of the interfacial tension between the components in the melt, translating to interfacial adhesion in the blend after processing. 

In systems such as these in which the phase-separated system is being formed and stabilized in the process of the reactive blending (often reactive extrusion) the effect of mechanical shear itself on the phase-separation process must be considered. 

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