Miscibility definition

Colloidal suspensions are, per definition, mixtures of mesoscopic particles and atomic liquids. What happens if there are several different species of particles mixed in the solvent One can invent several different sorts of mixtures small and large particles, differently charged ones, short and long rods, spheres and rods, and many more. Let us look into the literature. One important question when dealing with systems with several components is whether the species can be mixed or whether there exists a miscibility gap where the components macroscopically phase-separate. 

If the temperature is changed the miscibility of the liquids alters, and at a particular temperature the miscibility may become total this is called the critical solution temperature. With rise of temperature the surface of separation between the liquid and vapour phases also vanishes at a definite temperature, and we have the phenomenon of a critical point in the ordinary sense. According to Pawlewski (1883) the critical temperature of the... 

Based on the above information, the CAMD problem definition is revised as follows - The solvent can be acyclic hydrocarbons and ketones (aromatic compounds, chlorides, dioxanes are not considered for EH S concerns). The normal boiling point should be higher than that of chloroform (334 K), the molecular weight could be between 70-120, the solvent must not form azeotrope with either acetone or chloroform, and, must be totally miscible with the binary mixture of acetone and chloroform. 

Note 3 A miscible system can be thermodynamically stable or metastable (see Note 4 in Definition 1.2). 

Curve defining the region of composition and temperature in a phase diagram for a binary mixture across which a transition occurs from miscibility of the components to conditions where single-phase mixtures are metastable or unstable (see Note 4 in Definition 1.2). 

Note 4 For components of chain structures that would be expected to be miscible, miscibility may not occur if molecular architecture is changed, e.g., by crosslinking. Modified from Definition 1.3 in [3]. The definition proposed here is preferred because it emphasizes the requirement for homogeneity over miscibility. 

It would be of considerable interest to have data for the surface and interfacial tensions of a pair of liquids such as nicotine and water which are miscible in all proportions except within a definite temperature range. Here we should expect to find curves of the type shown in the figure, where a and h represent the surface tensions of the two phases within the critical region and c their interfacial tension. The latter has no meaning either above or below the critical temperatures and must have a maximum at some intermediate point. 

Semiaqueous or Nonaqueous Solutions. Although the measurement of pH in mixed solvents (e.g., water/organic solvent) is not recommended, for a solution containing more than 5% water, the classical definition of a pH measurement may still apply. In nonaqueous solution, only relative pH values can be obtained. Measurements taken in nonaqueous or partly aqueous solutions require the electrode to be frequently rehydrated (i.e soaked in water or an acidic buffer). Between measurements and after use with a nonaqueous solvent (which is immiscible with water), the electrode should first be rinsed with a solvent, which is miscible with water as well as the analyte solvent, then rinsed with water. Another potential problem with this type of medium is the risk of precipitation of the KC1 electrolyte in the junction between the reference electrode and the measuring solution. To minimize this problem, the reference electrolyte and the sample solution should be matched for mobility and solubility. For example, LiCl in ethanol or LiCl in acetic acid are often used as the reference electrode electrolyte for nonaqueous measurements. 

In Flory s theory (/< ), a polymer-solvent system is characterized by a temperature 0 at which (i) excluded-volume effects are just balanced by polymer-solvent interactions, so that os=l, (ii) the second virial coefficient is zero, irrespective of the MW of the polymer, and (iii) the polymer, of infinite molecular weight, is just completely miscible with the solvent The fundamental definition of the temperature is a macroscopic one, namely that for T near 0 the excess chemical potential of the solvent in a solution of polymer volume fraction v2 is of the form (18) ... 

When two (or more) metals are melted together and the melt is allowed to solidify, the product is called an alloy. (Sometimes alloys contain nonmetals such as carbon.) Since metals are more widely used as alloys than in pure condition, the nature of alloys has been the subject of much study. It has been found that some metals are miscible in all proportions, while with other pairs there is a definite limit to solubility. When a melted mixture cools, there may crystallize out (1) pure metal, (2) a solid solution, (3) a definite compound, (4) or a mixture of any of these. In the simplest case, one or the other pure metal (components) crystallizes as the temperature falls until the lowest melting point of... 

Bismuth Arsenides.—When bismuth and arsenic are melted together there is no evidence of chemical combination. The two elements are only slightly miscible in the molten state 7 and separate completely on solidification if an open vessel is used, but according to Heike 8 they are perfectly miscible if melted in a sealed tube. Descamps 9 melted a mixture of bismuth and excess of arsenic under fused boric oxide, keeping the temperature as low as possible, and obtained a product of density 8-45 and approximate composition Bi3As4, but it is doubtful whether this was a definite compound. 

The amphiphilic material to be studied is dissolved at a known concentration in a volatile solvent which is not miscible with water and a known quantity is spread at the water surface using a micropipette. In order to study the physical properties of the film thus formed, one needs to be able to confine the film to a definite area and to be able to vary this area at will. It might appear that it would be equally possible to maintain a constant area and vary the amount of material which is spread. For the majority of materials this latter procedure is not satisfactory as equilibrium is not arrived at in a reasonable period of time and this method would not allow one to take the material through successive cycles of compression and expansion. We thus turn to a discussion of the various ways in which a film can be confined and its area varied in a systematic manner. Leaving aside methods which are really only of historical interest, for which reference should be made to the book by... 

Tg of either polymer components. In addition to the two distinguishable Tg signals, the melting endotherm and cold-crystallization exotherm of CA are both detectable for every blend at almost the same temperature positions as those for the CA (DS = 2.95) alone, with a proportional reduction of the respective peak areas. In contrast to the result, the thermograms compiled in Fig. 9a for the pair of CA (DS = 2.70) and P(VP-co-VAc) (VP/VAc = 0.51/0.49) (combination A) indicate a definitely single Tg that shifts to the higher temperature side with increasing CA content. As summarized in Fig. 8, CA/PVAc blends are immiscible irrespective of the DS of the CA component, while PVP forms a miscible monophase with CAs unless the acetyl DS exceeds a value of... 

Snyder, Glajch and Kirkland [570) introduced two new parameters to describe the selectivity effects in the optimization triangle for LSC. If methylene chloride (MC), acetonitrile (ACN) and methyl t-butyl ether (MtBE) are used as the preferred modifiers in n-hexane, then an empirical solvent selectivity parameter (m) can be defined which is low for methylene chloride and can be made equal for the other two binary solvents. The latter is achieved by adding the appropriate amount of methylene chloride to the hexane-ACN binary. Addition of MC is required at any rate, because hexane and ACN are not miscible in all proportions. By definition we can assume m to equal zero for the hexane-MC binary mixture and m to equal one for the two other binaries. 

This article reviews the phase behavior of polymer blends with special emphasis on blends of random copolymers. Thermodynamic issues are considered and then experimental results on miscibility and phase separation are summarized. Section 3 deals with characteristic features of both the liquid-liquid phase separation process and the reverse phenomenon of phase dissolution in blends. This also involves morphology control by definite phase decomposition. In Sect. 4 attention will be focused on flow-induced phase changes in polymer blends. Experimental results and theoretical approaches are outlined. 

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