Dispersed phases crystallizable, blends with

Blends with a Crystallizable Matrix and an Amorphous Dispersed Phase... 

In the case of immiscible blends with a crystallizable matrix, the spherulite growth can be disturbed to a certain degree by the presence of an amorphous phase component, dispersed in the crystallizable melt. 

The behavior of binary blends with only one crystaUizable component has been studied by several authors, who have investigated different systems. The crystals of the crystaUizable matrix have grown in equilibrium with their own melt phase. The presence of separate domains of non-crystallizable component, dispersed in the molten matrix during the crystallization process, (owing to the kinetic and morphological effects), may cause a depression of the observed melting tem-... 

The formation of miscible rubber blends slows the rate of crystallization (Runt and Martynowicz, 1985 Keith and Padden, 1964) when one of the components is crystallizable. This phenomenon accounts for data that show lower heats of fusion that correlate to the extent of phase homogeneity (Ghijsels, 1977) in elastomer blends. Additionally, the melting behavior of a polymer can be changed in a miscible blend. The stability of the liquid state by formation of a miscible blend reduces the relative thermal stability of the crystalline state and lowers the equilibrium melting point (Nishi and Wang, 1975 Rim and Runt, 1520). This depression in melting point is small for a miscible blend with only dispersive interactions between the components. 

Blends with a Crystallizable Dispersed Phase in an Amorphous Matrix. 392... 

Blends with a crystallizable matrix and an amorphous dispersed phase... 

Blends with an amorphous matrix and a crystallizable dispersed phase... 

Polymer Blends with Amorphous Matrix and Crystallizable Dispersed Phase. 294... 

However, in the case of immiscible blends with a crystallizable matrix, the spherulite growth can be disturbed to a certain degree by the presence of an amorphous dispersed phase and intentional seeding (nanofillers) localized in the crystallizable matrix or at the interface. In the presence of molten or glassy dispersed phase, along the path of crystallization growth front can markedly disturb the... 

POLYMER BLENDS WITH AMORPHOUS MATRIX AND CRYSTALLIZABLE DISPERSED PHASE... 

For blends with a crystallizable dispersed phase that involves fine droplets in the matrix, crystallization can occur in several steps upon cooling from the melt, initiated at different undercooling points (i.e., fractionated crystallization) [90]. Fractionated crystallization is identified by the presence of more than one crystallization peak in the DSC exotherm (Figure 14.1). 

When a crystallizable dispersed phase is used, fiactionated crystallization may occur. In such a confined polymer phase, the composition and surrounding conditions will play a major role in the crystallization processes. The structures of the aystals formed are defined by the following factors MW, microstructure of the polymer chain fusion condition prior to crystallization, miscibility, etc., therefore, to effectively develop polymer blends with improved crystallinity, the necessary factors must be carefully considered. 

A completely different behavior is reported for blends in which the crystallizable phase is dispersed. Fractionated crystallization of the dispersed droplets, associated with different degrees of undercooling and types of nuclei is the rule. The most important reason is a lack of primary heterogeneous nuclei within each crystallizable droplet. An important consequence of fractionated crystallization may be a drastic reduction in the degree of crystallinity. 

However, for polymer blends in which the crystallizable phase is dispersed into fine droplets in the matrix, crystallization upon cooling from the melt can sometimes occur in several steps (fractionated crystallization) that are initiated at different undercooling, often ending up with a crystallization at the homogeneous crystallization temperature T, [Aref-Azar et al., 1980 Bailtoul et al., 1981 Ghijsels et al., 1982 Santana and Muller, 1994]. 

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