Blend polymer blends, phase behavior

Meredith JC, Karim A, Amis EJ (2000) High-throughput measurement of polymer blend phase behavior. Macromolecules 33 5760-5762... 

FIGURE 16 General phase diagram of polymer blends, phase behavior can be monitored in the window between and T, areas enclosed by the curves are regions of phase instability. 

Paul, D.R. (1985) Polymer blends. Phase behavior property relationship in Multicomponent Polymeric Materials (Eds D.R. Paul, LH. Sperling), AtAmices in Chemistry Series, 211, American Chemical Society, Washington D.C.,... 

Kipper, M.J. Seifert, S. Thiyagarajan, P. Narasimhan, B. Understanding polyanhydride blend phase behavior using scattering, microscopy, and molecular simulations. Polymer 2004, 45 (10), 3329-3340. 

The above systems are fairly simple, homogeneous systems since they contain only one polymer in the matrix. Blending polymers makes the behavior more complex. In polypropylene/polycarbonate blends, carbon black is preferentially located in the polycarbonate phase. A blend which is better mixed is less conductive than a blend in which carbon black predominantly resides in the polycarbonate phase where it can form a conductive network. These are properties which control morphology (and related electric conductivity) ... 

Penning JP, Manley RSJ. Miscible blends of two crystalline polymers 1. Phase behavior and miscibility in blends of poly(vinylidene fluoride) and poly(l,4-butylene adipate). Macromolecules 1996 29(l) 77-83. 

Hemmati, F, Garmabi, H., and Modarress, H. (2014]. Effects of Organoclay on the Compatibility and Interfacial Phenomena of PE/EVA Blends with UCST Phase Behavior, Polym. Compos, 35,2329-2342. 

Chapter 1 is devoted to molecular simulation of polymer melts and blends, including methods, phase behavior, interfaces, and surfaces that are currently the... 

Ternary Blends. Discussion of polymer blends is typically limited to those containing only two different components. Of course, inclusion of additional components may be useful in formulating commercial products. The recent Hterature describes the theoretical treatment and experimental studies of the phase behavior of ternary blends (10,21). The most commonly studied ternary mixtures are those where two of the binary pairs are miscible, but the third pair is not. There are limited regions where such ternary mixtures exhibit one phase. A few cases have been examined where all three binary pairs are miscible however, theoretically this does not always ensure homogeneous ternary mixtures (10,21). 

A variety of experimental techniques have been used to prepare and characterize polymer blends some of the mote important ones for estabHshing the equiHbtium-phase behavior and the energetic interactions between chain segments ate described here (3,5,28,29). 

The hterature contains extensive reports on investigations of the equiUbrium-phase behavior for an enormous number of polymer—polymer pairs (1,97). The number of blends known to be miscible has grown so rapidly since the mid-1980s that it is more instmctive to attempt to understand these observations in terms of the molecular stmctures of the components rather than to catalog them. 

Flow behavior of the polymer blends is determined by their structure, which is governed by the degree of dispersion of the component and by the mode of their distribution. For blends having identical compositions, it is possible to produce systems in which one and the same component may be either a dispersion medium or a dispersed phase [1]. This behavior of the polyblend systems depends on various parameters, the most important of which is the blending sequence. It is, therefore, difficult to obtain a uniform composition property relationship for the polymer blends even though the composition remains identical. 

The flow behavior of the polymer blends is quite complex, influenced by the equilibrium thermodynamic, dynamics of phase separation, morphology, and flow geometry [2]. The flow properties of a two phase blend of incompatible polymers are determined by the properties of the component, that is the continuous phase while adding a low-viscosity component to a high-viscosity component melt. As long as the latter forms a continuous phase, the viscosity of the blend remains high. As soon as the phase inversion [2] occurs, the viscosity of the blend falls sharply, even with a relatively low content of low-viscosity component. Therefore, the S-shaped concentration dependence of the viscosity of blend of incompatible polymers is an indication of phase inversion. The temperature dependence of the viscosity of blends is determined by the viscous flow of the dispersion medium, which is affected by the presence of a second component. 

Miscible Polymer Blends A subclass of polymer bends encompassing those blends that exhibit single-phase behavior. 

In contrast to two-phase physical blends, the two-phase block and graft copolymer systems have covalent bonds between the phases, which considerably improve their mechanical strengths. If the domains of the dispersed phase are small enough, such products can be transparent. The thermal behavior of both block and graft two-phase systems is similar to that of physical blends. They can act as emulsifiers for mixtures of the two polymers from which they have been formed. 

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