Miscibility behavior

Figure 7,1 Relationships between chemical potential and composition in binary phases with different miscibility behavior a = complete miscibility ]8 = partial miscibility y = lack of miscibility or mechanical mixture. ...

In system (i), 6ED and LiFOS exhibit miscibility behavior similar to a mixed system consisting of two hydrocarbon surfactants, such as 6ED and SDS. Mixed micelles are formed over a wide range of concentrations. 

The miscibility behavior of ionic liquids and organic solvents is also rather unpredictable dichloromethane and THF mix with, e.g., [BMIm][ Tf2N], whereas alkanes and ethers do not, and ethyl acetate seems to be a borderline case [35]. Supercritical carbon dioxide (scC02) does not mix with ionic liquids such as [BMIm][PF6] and [OMIm][BF4], but is absorbed in the ionic liquid phase in huge amounts (up to a molar fraction of 0.7) [36]. No ionic liquid dissolves in the C02 phase. 

Recording surface pressure/area isotherms is a relatively simple method for describing the miscibility behavior of a two component lipid mixture. The mean area per molecule of a binary mixture can be calculated using the following equation ... 

In mixed bilayer vesicles diacetylenic and natural lipids exhibit the same miscibility behavior as in monomolecular films. This can be demonstrated using differential scanning calorimetry (DSC). The neutral lipid (23) is immiscible with DSPC or DOPC as indicated by the two phase transitions of the mixed liposomes which occur at the same temperatures as those of the pure components (Fig. 33 a). 

Kressler J, Kammer HW (1987) Miscibility behavior of poly(2,6-dimethylphenylene oxide) and poly(styrene-co-acrylonitrile). Acta Polym 38 600-602... 

The different properties of ILs, with regard to their polarity, hydrophobicity, and solvent miscibility behavior through combination with different anions, are the reason for the different biocatalyst activities. Good to excellent activity of CALB was observed with a decrease in polarity and hydrophobicity and a viscosity increase of the ILs. In [bmim][PF6] a conversion of (R)-l-phenylethanol into the ester of 48.9% and an ee of 95.6% were achieved after 5h and 100% of (R)-l-phenylethanol was converted into the enantiopure (R)-l-phenylethyl acetate after a 1-day reaction. Immobilized CALB exhibited excellent stability, activity, and selectivity towards the (R)-enantiomer of 1-phenylethanol in [bmim][PF6]. In some research bis(trifluoromethylsulfonyl)imide-based ILs have been regarded as very suitable media for biocatalysis [39, 46, 50]. On the contrary, in the present work, lower suitability of the same IL was demonstrated. Since immobilized CALB catalyzed both hydrolytic and transesterification reactions, its enantioselectivity for long reaction times was lower. 

Based on the pioneering work of Molau [64], it is evident that phase separation can occur in blends of two or more copolymers produced from the same monomers when the composition difference between the blend components exceeds some critical value. The mean field theory for random copolymer-copolymers blends has been applied to ES-ES blends differing in styrene content to determine the miscibility behavior of blends [65,66]. On the basis of the solubility parameter difference between PS and PE, it was predicted that the critical comonomer difference in styrene content at which phase separation occurs is about 10 wt% S for ESI with molecular weight around 105. DMS plots for ES73 and ES66 copolymers and their 1 1 blend are presented in Figure 26.8. 

Dorfler HD. Relationships between miscibility behavior and chemical structure of phospholipids in pseudobinary systems. Colloid Polym. Sci. 2000 278 130-136. 

Results from these calculations with varying strength of the unlike-pair interactions are presented in Fig. 2. Clearly, if one artificially varies the strength of the unlike-pair interactions, the systems that result are hypothetical, and no longer represent real mixtures of acetone and CO2. For simplicity, we will still refer to the components of these hypothetical mixtures as acetone and CO2. The results are expressed as mole fractions of CO2 in the acetone-rich (liquid) phase and mole fractions of acetone in the C02-rich (fluid) phase, as functions of pressure. Miscible behavior was observed for - 1 (the base case) and 0.90, while immiscibility that persists for pressures significantly higher than the critical pressure of pure C02... 

If C < A, then the solvent having miscibility number C is somewhat less lipophilic than the solvent with numbers A and B. At this end of the lipophilicity scale, the number B characterizes the solvent s miscibility behavior. Apply rules 1 through 3, using A = B - C. 

If a compound of interest is not listed in Table 15-3 or 15-4, a compound of the same type or class may help to gauge its miscibility behavior. In cases where Godfrey s rules indicate that partial miscibility is likely, whether phase splitting actually occurs depends upon the composition of the mixture and the temperature. The composition may be close to but still outside the two-liquid-phase region on a temperature-composition diagram. 

IGC was used to determine the thermodynamic miscibility behavior of several polymer blends polystyrene-poly(n-butyl methacrylate), poly(vinylidene fluoride)-poly(methyl methacrylate), and polystyrene-poly(2,6-dimethyl-1,4-phenylene oxide) blends. Specific retention volumes were measured for a variety of probes in pure and mixed stationary phases of the molten polymers, and Flory-Huggins interaction parameters were calculated. A generally consistent and realistic measure of the polymer-polymer interaction can be obtained with this technique. 

M. Muller (1999) Miscibility behavior and single chain properties in polymer blends a bond fluctuation model study. Macromol. Theory Simul. 8, pp. 343-374 M. Muller and K. Binder (1995) Computer-simulation of asymmetric polymer mixtures. Macrrmolecules 28, pp. 1825-1834 ibid. (1994) An algorithm for the semi-grand-canonical simulation of asymmetric polymer mixtures. Computer Phys. Comm. 84, pp. 173-185... 

A group of new, fully miscible, polymer blends consisting of various styrene-maleic anhydride terpolymers blended with styrene-acrylonitrile copolymer and rubber-modified versions of these materials have been prepared and investigated. In particular the effects of chemical composition of the components on heat resistance and the miscibility behavior of the blends have been elucidated. Toughness and response to elevated temperature air aging are also examined. Appropriate combinations of the components may be melt blended to provide an enhanced balance of heat resistance, chemical resistance, and toughness. 

S/MA/MM). Miscibility behavior of typical matrix pairs is discussed as a function of composition, and discussion of material behavior in this work emphasizes response to elevated temperatures and to stress at temperature extremes. Thus, glass transition temperature (Tg), distortion temperature under load (DTUL), and tensile deformation properties as a function of temperature are reported for various typical blend combinations. Also discussed are the results of elevated temperature air aging studies on a typical blend compared to ABS. 

Figure 3. Glass transition temperature-composition plots for various SANHS/MA MM blends to illustrate miscibility behavior.

Now let s examine the miscibility situation of supercritical CO2 with the same liquids at 400 bar and 40°C the solubility parameter of CO2 is about 7.3. Carbon dioxide at 400 bar is miscible with hexane, so again we might be pleased with the fact that 82- 81 = 1 predicts miscibility behavior. But CO2 is also miscible with methanol, DMF, NMP, and DMSO, and the solubility parameters for the respective four liquids are clearly different by more than 1 H. How do we explain that CO2 is miscible with the liquids Although CO2 is strictly a nondipolar molecule, i.e., its dipole moment is zero, it has strong bond dipoles or, equivalently, a large quadrupole, which can interact with other polar molecules. 

As a reaction proceeds, the resultant product species, if it contains a different functional group compared with the reactant, may induce the reactant-product-SCF mixture to split into multiple phases near the critical point of the SCF. The work of Francis (1954), Dandge, Heller, and Wilson (1985), and Stahl and coworkers (Stahl and Quirin, 1983 Stahl et al., 1980) should be consulted for information on the types of functional groups that affect the miscibility behavior of solute-SCF mixtures. Chapter 3 shows that binary mixtures tend to exhibit multiphase LLV behavior as the differences in the molecular weights of the mixture components increase (Rowlinson and Swinton, 1982), so it is reasonable to assume that a reacting mixture would also... 

Hottovy, J. D., J. P. Kohn, and K. D. Luks. 1981. Partial miscibility behavior of the methane + ethane + n-octane system. J. Chem. Eng. Data 26 135. 

Partial miscibility behavior of the ternary systems methane + propane +... 

Figure 6. la shows an example of the free energy density of mixing, gm, plotted as a function of 02, for a mixture that exhibits a miscibility gap. The relationship between the shape of such a gm-02 curve and the miscibility behavior is discussed in most textbooks on polymers and polymer blends. The following is a very brief description of the significance of the binodal and spinodal points in phase diagrams. 

The observed regularity in the miscibility behavior for a series of polymers can be better understood considering that two polymers are composed of individual interacting groups. 

The presence of hardener hexahydrophthalic anhydride (HHPA) in the blends completely changed the miscibility behavior of the blends. All the blends became heterogeneous upon adding HHPA. The phase behavior of the ternary blends was evident from the phase diagrams given in Fig. 21.2. 

If the three solubility parameter components for dispersion forces 5, dipole forces p, and hydrogen bonds plotted on a three-dimensional space diagram (Fig. 2), a system is obtained in which a vector S is defined for each solvent. The vector describes the solvent s solubility and miscibility behavior [14.28], [14.29]. Solvents that lie close to one another in this space diagram (i.e., whose vector difference is small) have similar solution properties and often a similar chemical structure. Solvents that are far apart on the diagram differ greatly in their chemical and physical characteristics they are generally immiscible [14.30]-[14.32], The solubility parameters as well as their components are shown for some solvents in Table 15. 

We report a preliminary study involving blends of PVC with chemically modified SAN s copolymers. The blends of PVC with the series of SAN s copolymer were prepared and examined for their glass transition temperature which is used as a criteria of miscibility of blends. The nature of the interactions in their blends was investigatied by using FT-IR spectroscopy. We believe that these results are used to understand, at least in part, the miscibility behavior of the blend of PVC with the series of the SAN s copolymer. 

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