Miscibility, factors affecting

Barrier polymers, 3 375-405 applications, 3 405 barrier structures, 3 394-399 carbon dioxide transport, 3 403 flavor and aroma transport, 3 403-405 health and safety factors, 3 405 immiscible blends, 3 396-398 large molecule permeation, 3 388-390 layered structures, 3 394-396 miscible blends, 3 398-399 oxygen transport, 3 402 permanent gas permeation, 3 380-383 permeability prediction, 3 399-401 permeation process, 3 376-380 physical factors affecting permeability, 3 390-393... 

The factors affecting the design of mechanically agitated liquid-liquid reactors are the miscibility of the liquid phases, the interfacial tension, and the densities and viscosities of the liquid phases, as well as the density and viscosity differences between the two liquids. As shown in Fig. 21, a variety of stirrer configurations are available to carry out liquid-liquid reactions. 

Harris, J. E., Factors Affecting Polymer-Polymer Miscibility The Relative Importance of Entropy and Enthalpy, Ph.D. Thesis, The University of Texas at Austin, Austin TX, (1981). 

Many factors affect solubility and must be considered. For example, pH, ionic strength, and temperature can significantly affect solubility. For example, the aqueous solubility of a carboxylic acid can be orders of magnitude higher at a pH above the pKa than below the pKa. This is due simply to changes in the polarity of the molecule. Conversely, the solubility of weak bases such as amines is higher when the pH is below the pKa of the base. For aqueous sample preparations, addition of a water-miscible solvent such as acetonitrile or alcohol can be used to enhance solubility. For example, the solubility of acetaminophen in water is approximately 11 mg/mL, but the solubility is doubled by adding 2% ethanol (19). 

From the data presented in this Table, it appears that in contrast to binary blends without a compatibilizer, the crystallization of the minor component in compatibilized blends cannot be solely explained by the size of the dispersion [Ikkala et al., 1993 Flaris et al., 1993 Tang and Huang, 1994a Holsti-Miettinen et al, 1995]. Other factors affecting the crystallization are the type of compatibilizer and its degree of miscibility with one or both of the blend components, the amount of compatibilizer added, the amount of interface created, and other effects. 

All compounds that contain PO4, CO3, SO3, and SO2 are insoluble, except for those of family 1 on the periodic table and NH4. Most hydrocarbon compounds are not soluble, such as gasoline, diesel fuel, pentane, octane, etc. Compounds that are polar, such as the alcohols, ketones, aldehydes, esters, and organic acids, are soluble in water. Several factors affect the solubility of a material. One is particle size the smaller the particle, the more surface area that is exposed to the solvent therefore, more dissolving takes place over a shorter period of time. Higher temperatures usually increase the rate of dissolving. The term miscibility is often used synonymously with the term solubihty. Solubility is also related to polarity insofar as those materials that are polar are generally soluble in other polar materials. Miscibility, solubility, polarity, and mixtures will be discussed as they pertain to specific chemicals and families of chemicals in other chapters of this book. 

C. Delfolie, L.C. Dickinson, K.F. Freed, J. Dudowicz, W.J. MacKnight, Molecular factors affecting the miscibility behavior of cycloolefin copolymers. Macromolecules 32(23), 7781-7789 (1999)... 

THERMODYNAMICS OF POLYMER MIXTURES FACTORS AFFECTING MISCIBILITY IN POLYMER BLENDS... 

Another factor affecting the capability to rinse complex part structures are the forces of surface tension. Films of a solvent with a relatively high value of surface tension may block flushing of complex surface structures. In other words, an SA cosolvent which is perfectly miscible (Class III) or immiscible (Class II) with an RA cosolvent, can t either dilute or displace, respectively, the RA cosolvent if surface forces block /limit its passage to meet the SA cosolvent. 

CRITICAL FACTORS AFFECTING PRODUCT PERFORMANCE Processing temperature should be controlled. Long exposure to 260°C may cause degradation. Mixing with other plastics should be avoided because Luran S is immiscible with most thermoplastics. PVC is partially miscible but still a number of special measures must be undertaken to obtain quality blends. Drying of resin is important, not because of mechanical performance (which remains fairly unaffected) but the presence of moisture gives a rise to streaks and blisters. 

One of the major factors affecting the structure and properties of polymer blends is their miscibility. Most polymer pairs exhibit pronounced immiscibility, and only certain pairs are thermodynamically miscible. Generally, polymer blends are at least two-phase non-homogeneous systems. 

Movements in the plane of the interface result from local variations of interfacial tension during the course of mass transfer. These variations may be produced by local variations of any quantity which affects the interfacial tension. Interfaeial motions have been ascribed to variations in interfacial concentration (H6, P6, S33), temperature (A9, P6), and electrical properties (AlO, B19). In ternary systems, variations in concentration are the major factor causing interfacial motion in partially miscible binary systems, interfacial temperature variations due to heat of solution effects are usually the cause. 

Describe the factors that affect the solubility of a solid in a liquid. What does it mean to say that two liquids are miscible ... 

The principal factor is the shape of the two-phase liquid-vapor region in the phase diagram (usually a temperature-composition diagram). The closer the liquid and vapor lines are to each other, the more theoretical plates needed. See Figure 6.15 of the text, But the presence of an azeotrope could prevent the desired degree of separation from being achieved. Incomplete miscibility of the components at specific concentrations could also affect the number of plates required... 

The miscibility and crystallization behavior of the three binary PE blends, HDPE/ LLDPE, HDPE/LDPE, and LLDPE/LDPE, were reviewed. In general, differences in the number, length, and distribution of branches in the PE blend components are the major factors governing their miscibility and crystallization phenomenon. In particular, the content and distribution of branches significantly affect both the miscibility and crystallization. Moreover, the presence of a few long chain branches, as well as... 

---