Blend polymer, incompatible

Characterization and control of interfaces in the incompatible polymer blends were reported by Fayt et al. [23]. They used techniques such as electron microscopy, thermal transition analysis, and nonradiative energy transfer (NRET), etc. They have illustrated the exciting potentialities offered by diblock copolymers in high-performance polymer blends. 

Note 5 The use of the term "polymer alloy for polymer blend is discouraged, as the former term includes multiphase copolymers but excludes incompatible polymer blends (see Definition 1.3). 

The electrical conductivity of two-phase, incompatible polymer blends containing carbon black has been shown to depend on the relative affinity of the conductive particles to each of the polymer components in the blend, the concentration of carbon black in the filler-rich phase, and the structural continuity of this phase [82]. Hence, by judicious manipulation of the phase microstructure, these three-phase filled composites can exhibit double percolation behaviour. 

PVC and EVA form incompatible polymer blends as indicated from permeability and opacity measurements. 

Structuring of polymer films attracts considerable attention, and various radiation sources have been employed to crosslink selectively suitable polymers for, e.g., waveguide fabrication [99], Incompatible polymer blends have been forced into certain demixing morphologies along pre-patterned surfaces [55], Persistent structures could be formed by laser radiation in various nonabsorbing polymer solutions, such as polyisoprene in n-hexane [57, 58],... 

Table 3.2 lists examples of compatible, partially incompatible, and incompatible polymer blends. 

Wu S (1987) Formation of dispersed phase in incompatible polymer blends interfacial and rheological effects. Poly Eng Sci 27(5) 335-343... 

Leibler L (1988) Emulsifying effects of block copolymers in incompatible polymer blends. Makromol Chem, Marcomol Symp 16 1-17... 

Dewetting of an Incompatible Polymer Blend on a Gold Surface ... 

For random copolymers and miscible polymer blends, only a single Tg, which is usually intermediate between the Tg of the corresponding neat homopolymers, is observed. For block copolymers with mutually incompatible blocks, the microdomains formed by the different blocks exhibit different Tg, and for incompatible polymer blends separate Tg values are also observed. 

Figure 5.15. MFC can be obtained from incompatible polymer blends by extrusion and orientation (the fibrillization step) followed by thermal treatment at a temperature between the melting points of the two components at constant strain (the isotropization step). The block copolymers formed during the isotropization (in the case of condensation polymers) play the role of a self-compatibilizer. Prolonged annealing transforms the matrix into a block and thereafter into a random copolymer (a) an MFC on the macro level, (b) an MFC on the micro (molecular) level (Fakirov Evstatiev, 1994).

The crystallization of the minor component in incompatible polymer blends starts sometimes at distinctly larger undercoolings than in the pure polymer, and proceeds in several separated steps. After a short survey on the history of the effect in the available literature, the several types and the origin of this "fractionated crystallization" as observed in some selected systems are described. The information on the blend which can be deduced from the effect is discussed, and the consequences for the blend processing and properties are investigated. 

The properties of incompatible polymer blends depend to a large extent on the mutual dispersion of the components, on the super-molecular structure within the phase of a single component, and on the structure of the interface. These structural parameters, in turn, depend on the processing or mixing conditions and on the strength of the thermodynamic incompatibility of the components as well. These boundary conditions together with the cooling rate control also the solidification process of a melt. 

For polymer blends with extended interfacial regions, these phenomena were reported to apply also to the bulk of the phase borders (12-16). The investigation of incompatible polymer blends revealed, e.g., the induction of specific crystal modifications (16), the rejection, engulfing and deformation of the dispersed component by the growing spherulites of the matrix material (4,17-19), and nucleation at the interface (4,20,23) ... 

This survey on the literature indicates that only few data are available on the droplet crystallization phenomena in incompatible polymer blends. Moreover, these observations are partly not completely explained, and, where explained, these explanations are partly not satisfying or contradictory. In the next chapter, therefore, experimental results for some selected systems as investigated by the authors are presented with the aim to show all faces and properties of fractionated crystallization in detail, and to contribute to a better understanding of the origin of the effect. 

It was the aim of the present paper to show that crystallization in incompatible polymer blends can exhibit a lot of peculiar effects beside the classical well known physical and physico-chemical phenomena. The effects considered here, in particular, are due to the dispersion structure of such blends, and to the changes in the crystallization nucleation conditions which are such caused. They are important from a physical, a material scientific, and a technological point of view as well. 

The phenomena on which has been reported here are linked to a droplet-like dispersion of the component under investigation. Therefore, they are usually exhibited only by the minor component in incompatible polymer blends. Both components, however, can exhibit the effects simultaneously if the dispersion is composed such that, in turn, a part of the matrix material is included into the particles of the dispersed component. These mentioned effects are mainly... 

Characterization of the interfacial regions is important to understand the mechanical properties of incompatible polymer blends. As shown, in many heterogeneous blends, the simplifying assumption of the neglect of spin diffusion between domains is reconcilable with NMR observations. In other words, most of the NMR observables are not sensitive enough to appreciate the influences of the other domains. However, it is also true that the spins are interacting with each other via the interface. To study such interactions. 

Both in compatible and in incompatible polymer blends, the dynamics of chains at interfaces and the static interfacial structure are of very great theoretical and practical interest [354-356] adhesion of polymer layers to walls, mechanical properties of inhomogeneous blends etc. may affect the application of polymeric materials, and at the same time fundamental questions are involved. This field of research is very active, and a complete coverage of the ongoing research in this area is not at all intended rather we indicate only a few topics that are closely related to problems treated in previous sections of the present review. 

Elemans, P. H. M., Modeling of the Processing of Incompatible Polymer Blends, PhD Thesis, Eindhoven University of Technology (1989). 

Min, K., J. L. White, and J. F. Fellers. 1984. Development of phase morphology in incompatible polymer blends during mixing and its variation in extrusion. Polymer Engineering and Science 24 1327-1336. 

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