Immiscible and miscible

Enhanced oil-recovery processes include chemical and gas floods, steam, combustion, and electric heating. Gas floods, including immiscible and miscible processes, are usually defined by injected fluids (carbon dioxide, flue gas, nitrogen, or hydrocarbon). Steam projects involve cyclic steam (huff and puff) or steam drive. Combustion technologies can be subdivided into those that autoignite and those that require a heat source at injectors [521]. 

Recently, a new concept in the preparation of TPVs has been introduced, based on the reaction-induced phase separation (RIPS) of miscible blends of a semicrystalline thermoplastic in combination with an elastomer, with the potential for obtaining submicrometer rubber dispersions. This RIPS can be applied to a variety of miscible blends, in which the elastomer precursor phase was selectively crosslinked to induce phase separation. Plausible schematic representation of the morphological evolution of dynamic vulcanization of immiscible and miscible blends is shown in Fig. 9. For immiscible blends, dynamic vulcanization leads to a decrease in the size... 

Fig. 9 Plausible representation of morphology evolution of reactive blending of immiscible and miscible blends...

The temperature dependence of the total interaction parameter shows that there exists an optimum condition for the composition at a given temperature (Fig. 3). Binary blends of PEO/PS and PEO/PAA are immiscible and miscible, respectively, at room temperature. The shape of curves implies that the homopol-ymer/homopolymer blends will exhibit UCST behaviors. A drastic effect of the sequence distribution on the miscibility can be found in Fig. 4. As the AA content in SAA increases from 5 mol% (Fig. 4a) to 7 mol% (Fig. 4b) to 10mol% (Fig. 4c), the blend becomes more miscible. The blend with random copolymers becomes miscible at a composition between 5 and 7 mol%, which agrees well with the experimental results [15]. At 7 mol%, the blend with block copolymers shows positive x> while the blend with random copolymers has negative y. This is very interesting because the miscibility could be controlled only by the change of copolymer sequence distributions. 

ILs can be divided in water-immiscible and -miscible compounds. Hydrophobic ILs typically consist of anions such as PF or Tf2N and the hydrophilic ILs of Cl , Br , BF or AICI4. According to Anthony et aL, the water miscibility is affected strongly by the anion [12]. Also the cation has its impact on water affinity, since when the alltyl chain is elongated, miscibility of the ionic liquid is decreased. 

D IR spectroscopy has been applied extensively to studies of polymeric materials. A recent review of 2D IR spectroscopy cites numerous applications in the study of polymers by this technique [6]. In this section, some representative examples of 2D IR analysis of polymers are presented. We will start our discussion with a simple homogeneous amorphous polymer then move to more complex multiphase systems, such as semicrystalline polymers. Alloys and blends consisting of more than one polymer components are of great scientific and technical importance. Both immiscible and miscible polymer blend systems may be studied by 2D IR spectroscopy. Analysis of microphase-separated block copolymers is also possible. Finally, the possible application of 2D IR spectroscopy to the studies of natural polymers of biological origin is explored. 

Most liquid solutions are obtained by dissolving a gas, liquid, or solid in some liquid. Soda water, for example, consists of a solution of carbon dioxide gas in water. Acetone, CsHgO, in water is an example of a liqnid—liquid solution. (Immiscible and miscible liquids are shown in Figure 12.1.) Brine is water with sodium chloride (a solid) dissolved in it. Seawater contains both dissolved gases (from air) and solids (mostly sodium chloride). 

Figure 25. Comparison of Immiscible and Miscible Filtrates photo by B.E. Beasley courtesy ExxonMobil Process Research)...

Tartakovsky, A.M., Meakin, R Pore scale modeling of immiscible and miscible fluid flows using smoothed particle hydrodynamics. Advances in Water Resources 29(10), 1464-1478 (2006)... 

Most polymers are not compatible with one another unless specific favorable interactions are present. This is because the favorable entropy of mixing is too small to overcome the unfavorable enthalpy of mixing, thus making the free energy of mixing unfavorable (2). A few pairs of immiscible and miscible polymers, respectively, are shown in Table 22.1. 

Table 22.1 Some Pairs of Immiscible and Miscible Polymers (3, p.

Nemoto, T., J. Takagi, and M. Ohshima. 2010. Nanocellular foams-cell structure ditference between immiscible and miscible PEEK/PEI polymer blends. Polymer Engineering Science 50 (12) (December30) 2408-2416. doi 10.1002/pen.21766. http //onlinelibrary. wiley.eom/doi/10.1002/pen.21766/fuU. 

The two generic terms found in the blend literature are compatibility and miscibility. Components that resist gross phase segregation and/or give desirable blend properties are frequently said to have a degree of compatibility even though in a thermodynamic sense they are not miscible. In the case of immiscible systems, the overall physicomechanical behavior depends critically... 

Add small amounts of each liquid indicated in step 2 to the water in the test tubes with the corresponding label. Stopper, shake, and observe the miscibility. Record the miscibility (miscible or immiscible) and polarity (polar or nonpolar) in a table such as the following in the data section of your notebook. 

Enzyme catalysis in nonconventional media can be divided into a number of different categories depending on whether the aqueous and organic phases are miscible or immiscible and whether the biocatalyst is dissolved or not. In this section, only free enzymes will be considered. Thus, the field can be simplified to just two categories, depending on whether the solvent is water miscible or immiscible (systems employing water-immiscible solvents, where water is present in quantities that are below its solubility limit, have been considered as monophasic) ... 

Blends are physical mixtures of polymers. Depending on the extent and type of blend the properties may be characteristic of each blend member or may be some blend of properties. Immiscible blends are phase-separated with the phases sometimes chemically connected. They are generally composed of a continuous and discontinuous phase. HIPS is an example of an immiscible blend. Miscible blends occur when the two blended materials are compatible. Often the properties are a mixture of the two blended materials. The plastic automotive panels and bumpers are generally made from a miscible blend of PE and a copolymer of PE and PP. 

Fig. 33. Map of immiscibility-miscibility-complexation transitions for PS(t-OH)/BVPy ( ) immiscible, (O) miscible and (0) complexed [148]...

As positive deviations (7.56) increase (as in oil-water mixtures), the tendency toward immiscibility and phase separation increases. In this case, the simple liquid region of (7.61) may separate into two distinct liquid phases one A-rich and one B-rich in composition. Such liquid-liquid partial miscibility is a ubiquitous feature of aqueous solutions of hydrophobic solutes, particularly at lower temperatures. 

Tables IV to VIII present in concise form, though complete, the data from five papers (17, 106, 121, 211, 372), each giving miscibilities of a group of substances. The papers are in the form of triangular or rectangular charts similar to mileage charts on road maps. In each square is given M or S for miscible, I for immiscible, and usually R for reacts. This method is unsatisfactory for more than about 50 liquids because of the large area required. Since about 70% of the pairs are miscible, much of the space is largely wasted.

Solvent manufacturer Honeywell Burdick Jackson [39] defines solvents as miscible if the two components can be mixed together in all proportions without forming two separate phases. A solvent miscibility chart (Figure 2.12) is a useful aid for determining which solvent pairs are immiscible and would therefore be potential candidates for use in LLE. More solvent combinations are miscible than immiscible, and more solvents are immiscible with water than with any other solvent. Solvents miscible with water in all proportions include acetone, acetonitrile, dimethyl acetamide, N,N-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, ethyl alcohol, glyme, isopropyl alcohol, methanol, 2-methoxyethanol, /V-methyI pyitoI idone. n-propyl alcohol, pyridine, tetrahydrofuran, and trifluoroacetic acid [40]. 

Time-temperature superposition works for homopolymers and miscible blends but not for immiscible blends, filled systems (e. g., glass fiber reinforced plastics) or reactive or unstable polymers. 

Leaving aside for the moment the relative advantages of immiscible vs. miscible blend systems, it is clear from the brief review above that the blend properties are strongly dependent on their phase structures and on the adhesion between phases. The presence and composition of phases as well as the surface energy of interaction between phases are, in principle, functions of the thermodynamics of interaction between the polymer components of the blend. Consequently, there is a need to be able to predict this interaction. 

The different catalytic responses of peroxidase in dioxane and methanol versus acetone are intriguing. It is clear that the effects of water-miscible solvents on enzymatic catalysis are not equivalent and for the first time quantitative kinetic data have been obtained which highlight this. However, the cause of this effect remains unresolved. We are continuing and expanding this kinetic study to include other solvents, both water-miscible and immiscible, and other phenols. This future study will enable rational and quantitative approaches for peroxidase-catalyzed phenolic polymerizations to be based on optimal solvent and phenol choices. From a more fundamental standpoint, this work has shown that enzymes may be more active in organic media than in water as long as optimal conditions are employed. There is no reason to believe peroxidase is unique in this respect. 

As the data in Table 4.3 show, the solubility parameter reflects how a chemist might rank these solvents in terms of polarity, e.g. water as the most polar (highest 5) and hexane as the least polar (lowest 8) but also one of the difficulties with this measurement of polarity is highlighted. The solubility parameter suggests that tetrahydrofuran (THE) and carbon tetrachloride are very similar even though carbon tetrachloride is immiscible with water whilst THE is miscible with water in all proportions. A similar comparison may be made between chloroform (8 = 19.1, water-immiscible) and acetone (8 = 20.2, water-miscible). 

To solve Equation (18), we construct the inhomogeneous site-site direct correlation function Coy (ri, F2) by the following procedure [47]. In the spirit of the approximation (3) for simple atomic fluid, we span it between the homogeneous site-site direct correlation functions c y (r p ) of coexisting bulk phases i with site densities p K (Here vector p denotes a set of densities [pa] for all sites a.) For an interface of two immiscible/partially miscible liquids, phase 1 with density p = p[ , is rich in component I and poor... 

The majority of polymers are immiscible and, in bulk, they phase separate to form domains of varying sizes and shapes, depending on their relative volume fraction. This happens because of the very low entropy of mixing in the case of large polymeric molecules. Therefore, unless there is a large favorable enthalpic contribution, most polymers do not form molecularly miscible systems. The same is true for block copolymers, in which the length of each block exceeds a certain critical value. As mentioned earlier, block copolymers are systems wherein two (or more) different types of homopolymers are linked to each other at the chain end(s) diblock copolymers, represented as (A) -(B) , are systems in which two homopolymers are linked to each other at one end, while triblock copolymers, represented as (A)m-(B) -(C)p, are systems in which one central homopolymer block is linked at either end with two other homopolymers. The values m, n and p, represent the... 

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