Phase Morphology Development in Polymer Blends

Sandararaj U. Phase morphology development in polymer blends Processing and experimental aspects. In Harrats C, Thomas S, Groeninckx G, editors. Micro- and Nanostructured Multiphase Polymer Blend Systems Phase Morphology And Interfaces. Boea Raton CRC Press 2006. 

Published investigations of phase morphology development in polymer melt blends in twin-screw extruders began with the work of Plochocki et al. [137] in 1988. Since 1992, several different research groups have described investigations [76,138-147]. 

Everaert V, Aerts L, Groeninckx G (1999) Phase morphology development in immisdble PP/(PS/PPE) blends influence of the melt-viscosity ratio and blend composition. Polymer 40 6627-6644... 

Several authors have developed empirical equations to predict the effect of coalescence on the phase morphology of binary polymer blends. Equation 1.4 relates the particle size of the dispersed phase at equilibrium to its composition in the blend [10]. This equilibrium equation was derived from a more complex expression where a rate constant for breaking fhe drops and one for fheir coalescence have been defined to account for the continuous process of phase morphology development resulting from a competition between breakup and coalescence. 

Reactive blending is an important technique which is very frequently used for control of the phase morphology, phase stabilization and interfacial adhesion in multiphase immiscible polymer blends. Recently a lot of attention has been focused on the reactive blending process in order to understand how phase morphology develops in reactively compatibilized blends. The stability of the in situ formed copol3aner at the interface and its influence on phase morphology generation, phase co-continuity and on the crystallization behavior of the ciystallizable component(s) are crucial aspects with respect to the blend material properties. 

A droplet-in-matrix phase morphology developed in immiscible polymer blends depends on the viscoelastic properties and composition of the two components of the blend in the melt state. The rheological formalism used for the non-Newtonian phases as polymer melts follows, with adjustment of the... 

Loyens W, Groeninckx G. Phase morphology development in reactively compatibiUzed polyethylene terephthalate elastomer blends. Polymer 2002 44 4929-4941. 

Fortelny, I. Theoretical aspects of phase morphology development. In Micro- and Nanostructured Multiphase Polymer Blend Systems, Harrats, C., Thomas, S., Groeninckx, G., eds. CRC Press, Taylor Francis, 2006. 

Figure 1. Phase morphology development in melt processing polymer blends.

A considerable amount of work has been done in the past in the development of blends with CC morphology and coarsening of the minority phase. However, most of the earlier work was intended towards understanding the coarsening and phase inversion mechanism in polymer blends [1-19]. To date, the fabrication of porous polymer fibers with CC morphology and subsequent coarsening of the minority phase with annealing has not been reported. 

In a fundamental sense, the miscibility, adhesion, interfacial energies, and morphology developed are all thermodynamically interrelated in a complex way to the interaction forces between the polymers. Miscibility of a polymer blend containing two polymers depends on the mutual solubility of the polymeric components. The blend is termed compatible when the solubility parameter of the two components are close to each other and show a single-phase transition temperature. However, most polymer pairs tend to be immiscible due to differences in their viscoelastic properties, surface-tensions, and intermolecular interactions. According to the terminology, the polymer pairs are incompatible and show separate glass transitions. For many purposes, miscibility in polymer blends is neither required nor de-... 

Table 7.6 provides a partial reference to studies on the effects of flow on the morphology of polymer blends [Lohfink, 1990 Walling, 1995]. Dispersed phase morphology development has been mainly studied in a capillary flow. To explain the fibrillation processes, not only the viscosity ratio, but also the elasticity effects and the interfacial properties had to be considered. In agreement with the microrheology of Newtonian systems, an upper bound for the viscosity ratio, X, has also been reported for polymer blends — above certain value of X (which could be significantly larger than the... 

In both martensite and pearlite two phases of contrasting mechanical properties are in close juxtaposition such morphologies in steels and other alloys should be compared with those of the polymer blends discussed in the next several chapters. The major point is that toughening depends upon fine-structure detail for both metallic alloys and polymer blends. While the above analogy was developed for polymer blends, similar analogies can be developed for polymer composites, as in Chapters 11 and 12. 

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