Polymer blends phases

Meredith JC, Karim A, Amis EJ (2000) High-throughput measurement of polymer blend phase... 

Fig. 14 Creation of a single specimen polymer blend phase diagram from orthogonal polymer composition and temperature gradients. The polymers are polystyrene and poly(vinyl methyl ether) (PVME) a composition library placed orthogonal to a temperature gradient b completed gradient library polymer blend phase diagram. White points are data derived from traditional measurement for comparison. See text for details, (b reproduced with permission from [3])...

Figure 5.1. Schematic illustrations of the general types of polymer blend phase diagrams, for the simplest case of binary blends without the additional complications that are sometimes introduced by competing processes such as the crystallization of one of the components. The coefficients dg and d refer to the general functional form for %Ag given by Equation 5.7 [10].

We now return to the mean field result for xg Eqs. (77), (78) but consider the case of quenching experiments that lead into the unstable regime of the polymer blend phase diagram case (iii) in Fig. 2. Then xs(4>o) — X is negative, and this implies also that xg is negative for q < qc using Eq. (78) one finds denoting xq 1 = R(q), the relaxation rate ... 

Meredith, J.C., Karim, A., Amis, E.J. High-throughputmeasurement of polymer blend phase behavior. Macromolecules 33, 5760-5762 (2000)... 

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. 

Fig. 10.26 Schematic illustration of types of possible polymer blend phase diagrams, for binary blends where additional complications that can be introduced by competing processes (such as crystallization of a component) are absent. The coefficients di and d2 refer to a general functional form (as a function of temperature and component volume fractions) of the binary interaction parameter that quantifies deviations from ideal mixing (Courtesy Online resources)...

Figure 1.22 Compatibilized dispersed polymer blend phase showing compatibilizing agents.

Most polymer blends phase-separate with LCST thus the miscibility region stretches from the melting point or Tg up to the binodal while the phase-separated region exists above the spinodal temperature, Ts [1, 212]. Within the region between binodal and spinodal the system is metastable, characterized by strong interrelation between the rheology and thermodynamics [211, 213-215]. 

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.,... 

Figure 6.34. Mechanical modulus of various polymer blend phase arrangements. The cube shows a unit cell model of an idealized IPN structure. The shaded area is determined by upper- and lower-bound estimates for this model. " ...

Section 4.3 delineated some of the basic notions of polymer blend phase diagrams. Principally due to the very small entropy of mixing and usually positive heats of mixing, two polymers will be immiscible unless some strong interaction such as hydrogen bonding exists between them. Since the number of mer-sized holes in a polymer depends on the interactions between the attractive forces and molecular motion of the polymer chains, lower critical solution temperatures are usually observed. 

In order to determine the phase behavior of heterogeneous polymer blends, phase diagrams are usually constructed in terms of the interaction parameter Xi2 and the composition or temperature and composition. Figure 3.2a represents the dependence of AG on as computed from the Flory-Huggins equation (Eq. (3.14)) for a symmetric binary blend (rj = V2 = r). The curves are shown for different values of Xi2> which is the only relevant parameter in the Flory-Huggins equation. For exothermic or adiabatic mixing G =J [Pg.101]

MISCIBILITY OF POLYMER-POLYMER BLENDS PHASE DIAGRAMS AND MOLECULAR INTERPRETATION... 

For a judicious control of the macroscopic properties of polymer blends, phase morphology constitutes a key parameter for many specific applications. The blending process of immiscible polymers in the melt state results in a heterogeneous morphology that is characterized by the shape, the size, and the distribution of the component phases. Depending on the composition, the homopolymer characteristics and the processing conditions used to mix them, two main types of morphologies are obtained, a dispersed type (a particle can be of any shape rod, platelet, flacks, disc, sphere, etc.) or a co-continuous one. 

Figure 6.5 Ternary polymer blend phase diagrams...

The miscibility limit between thermotropic liquid crystal polymers and flexible chain polymers can be predicted by calculations corresponding to the spinodal curve at constant temperature. This miscibility is increased with the increase of the degree of disorder (y/jc,) of the liquid crystal polymer and with the decrease of the degree of polymerization. Two quantitative parameters from the Hory s lattice theory can be used to estimate the phase behavior of this kind of blend at melt processing temperature the polymer-polymer interaction parameter and the degree of disorder (y/Xj). In binary polymer blends phase separation may occur for any value of degree of disorder (y/Xj)... 

For a symmetric polymer blend phase separation occurs already for x > Xait — 2/iV 1... 

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