Morphology and Crystal Nucleation

The formation of droplet-in-droplet morphology (or composite droplet morphology) has also been reported for immiscible systems (Fig. 10.14). For binary blends this type of morphology can be spontaneously generated when blending is carried out near the phase inversion region of the two polymer components. The formation of the inclusions is mainly controlled by the value of the interfacial tension. 

The presence of co-continuous phase morphology, which consists of at least two coexisting, continuous, and interconnected phases throughout the whole blend volume, is the other important superstructural characteristic 

Figme 10.14 SEM micrograph of the fracture surface of a polyamide-6 (PA6)/PP (40/60) blend obtained by extrusion from the melt at 250°C [114]. 

For immiscible blends with crystaUizable matrix and amorphous dispersed phase, the crystal growth and the final morphology can be significantly influenced by the noncrystallizable component, with large changes in the primary nucleation density (number of nuclei per unit volume of crystallisable polymer), as well as in the size, shape, size distribution, texture, and crystallinity degree of the spherulitic superstructures. 

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