Miscible polymer blends binary

A number of miscible polymer blends are only completely miscible and form one-phase systems over a limited concentration, temperature and pressure range. Under certain conditions of temperature, pressure and composition, miscible binary blends may phase separate into two liquid phases with different compositions. Important characteristics of this type of blends are the overall blend composition, the morphology and the composition of the different phases as well as the nature of the interface between the phases. 

Besides the dynamic heterogeneity discussed above, binary miscible polymer blends can be considered as dynamically asymmetric if the two components have a large difference in the glass transition temperatures. Usually the dynamic asymmetry is defined by A = where x " is the relaxation time of the... 

Several polymer blends that are commercial products in the industry are partially miscible. Partially miscible polymer blends are those that exhibit some shift from their pure component glass transition temperatures. Thus, a binary miscible polymer blend will exhibit one glass transition temperature and a partially miscible polymer blend will exhibit two distinct glass transition temperatures different from their pure component glass transition temperatures. Some experimental systems that have been reported as partially miscible polymer blends are PET and poly(hydroxy butyrate) (PHB) and PC/SAN. Later on, in a separate chapter, a mathematical framework... 

Miscible polymer blends act as single-phase systems that combine the properties of pure components so that the stability criteria for binary mixtures with composition fixed temperature T and pressure p, are expressed as... 

In this section, we present the molecular theory for the linear dynamic viscoelasticity of miscible polymer blends by Han and Kim (1989a, 1989b), which is based on the concept of the tube model presented in Chapter 4. Specifically, the reptation of two primitive chains of dissimilar chemical structures under an external potential will be considered, and the expressions for the linear viscoelastic properties of miscible polymer blends will be presented. We will first present the expressions for zero-shear viscosity ob. dynamic storage and loss moduli G co) and G " co), and steady-state compliance J° for binary miscible blends of monodisperse, entangled flexible homopolymers and then consider the effect of polydispersity. There are a few other molecular theories reported... 

At present, the thermorheological complexity of chain dynamics and rheological behavior of miscible polymer blends are not well understood. It has been reported that the monomeric friction coefficient of a miscible binary blend varies with blend composition in such a very complicated manner that at present there is no general rule that enables one to predict the viscosities of binary blends, even when the monomeric friction coefficients of the constituent components are known. This is a fundamental and very important subject that should receive serious attention of polymer scientists in the future. 

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). 

This dependence of the strength of the silanol self-association on the substituents provided an approach for tailor-made miscibility in their binary hydrogen bonded polymer blends.10 A miscibility window was formed for ST-VPDMS/PBMA blends when the copolymers contained 4 to 34 mol % silanol groups." As a direct result of reduced silanol self-association in ST-VPMPS copolymers, a extended miscibility window was formed when ST-VPMPS copolymers contained 9 to 56 mol % silanol groups.12... 

For simplicity, assuming that the close-packed volume of a PS mer (vps) is equal to that of a PVME mer (vPVME), the binary polymer blend is miscible [20] when... 

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