Solubility envelope

The use of the solubility envelope, together with the volumetric additivity rule for calculating solubility parameters of solvent blend and the solvent evaporation model described previously, allows an approximate assessment whether phase separation will take place or not during solvent evaporation. 

Figure 2. Ternary vapor-liquid equilibrium data for the one-phase region at 730 mm mercury absolute pressure with the solubility envelope for 60°C...

Increasing the concentration of the weak nonsolvent poreformer, ethanol. In a casting solution containing CA and acetone Increases the porosity of the resultant membranes (Table VI). Because the poreformer Is a nonsolvent, solution compatibility decreases with Increasing ethanol concentration. As the concentration of ethanol Is Increased, the solution approaches the point of incipient gelation that is, the perimeter of the solubility envelope. 

Because a solution containing a high concentration of nonsolvent can be presumed to be of the Sol 2 type and close to gelation. Immersion into a nonsolvent bath and subsequent gelation will be accompanied by less gel concentration than would occur If the solution were further removed from the perimeter of the solubility envelope. The result is that the micelle diameter in Sol 2, as well as the porosity and permeability of the final membrane. 

Note Oiv+i and Vb are not on the solubility envelope because they are entering streams and are not necessarily in equilibrium. 0 and Vn, however, are on the solubility envelope since they are exit streams and leave the column in equilibrium with each other.]... 

Since Vo is pure B and On+i and D have no solvent present, the line connecting pure B and On+i and D must contain Vn, which must also be on the solubility envelope... 

Vi and O2 can also be plotted from the given information because they both lie on the solubility envelope (they are leaving the column in equilibrium). The intersection of the lines Oq Vi and O2 locates the A point. 

The mixing point is also shown on the graph, but it is not used to locate Vi as usual since Vi is already specified. A tie-line through Vi locates the point Oi, and the line AOi crosses the solubility envelope at the point V2. 

Figure 8-12. Calculated residue curve map for ethanol-water-benzene (Doherty and Malone. 20011. The black squares are binary homogeneous azeotropes, the black tiiai le is a heterogeneous binaiy azeotrope, the black dot in the center of the diagram is a heterogeneous ternary azeotrope, and the dot-dash line represents the solubility envelope for the two liquid layers.

A special feature in this book is the inclusion of the Hansen solubility parameter theory that can be used to classify solvents in terms of their nonpolar, polar and hydrogen bonding characteristics. Use of the Hansen solubility parameter theory will allow the worker to systematically search for a solvent substitute or determine the solubility of a resin/polymer in a certain solvent or solvent blend. The files necessary to construct computer spreadsheets that can utilize the Hansen solubility parameter theory are included with this book. The useful spreadsheet files on a computer disk are included in a plastic pocket on the back inside cover of the book. These files can be used on an IBM-compatible computer with Lotus 123 (or Excel) software. These computer spreadsheets were developed in the Lotus 123. WKl file format. The data files can be used with the Lotus 123 Version 5.0 for Windows, the Microsoft Excel Version 5.0 for Windows or any earlier version of the spreadsheet software. The files can also be translated into the Macintosh Excel format if the correct version of Excel is available. The coating industry will find the information on solvent substitution using the Hansen solubility parameter theory of particular interest. The use of computer spreadsheets to compare the solubility envelope of the polymer with likely solvent candidates has been very helpful to the author in past work and others in the coating in selecting substitute solvents or solvent blends. The Hansen solubility parameter values for 166 resins and polymers and 289 solvents are listed. 

Figure 4.1 The idealized spherical solubility envelope for a polymer. The total solubility parameter 5f of a material is a point in three dimensional space where the three partial Hansen solubility parameter vectors meet. The Hansen parameters are the nonpolar bd, polar bp and hydrogen bonding 5 components. Source [4].

The hydrogen-bonding versus polarity plots are often used to describe the solubility envelope of a resin. While these envelopes do not match the theoretical circle or- sphere as shown in the Hansen theory, the plots are a useful method to represent solubility data. An in-depth look at these solubility plots is discussed in Chapter 5. 

Table 7.7 lists the solvent-resin radius of interaction values, of five resins with each of twelve alcohols. These values are a measure of the solubility of the resin in the solvent. As described in Chapter 5 the total solubility parameter of a resin is the point in three-dimensional space where the three partial solubility parameter vectors meet as the center point of the idealized spherical solubility envelope. The distance in space between two sets of solvent-resin parameters can be represented by the term radius of interaction or The spreadsheet SPWORKS.WKJ, which lists some 166 resins and polymers and 289 solvents, was used to calculate the R values given in Table 7.7. Small R values (e.g., less than 10) signify good solvency for the resin while higher values suggest a poor solvent for the resin. If the actual radius of the resin solubility envelope is known then the R value should be less than the resin radius if the solvent is to dissolve the resin.

If the actual radius of the resin solubility envelope is known then the value should be less than the resin radius if the solvent is to dissolve the resin. 

The phenol-soluble envelope fraction of Escherichia coli has been shown to consist of at least three distinct glycoproteins one of them has an appreciable rate of turnover and is thought to be involved in the transfer of carbohydrates in the envelope. Analysis of the outer- and inner-membrane glycoproteins showed that they are not identical. The principal envelope protein of Halobacterium salinarium is also a glycoprotein of molecular weight 1.94 x 10 . ... 

The radiius of interaction parameter expresses the degree of mutual solubility. Reasonable compatibility between solvent and resin/polymer is determined if the value of R li < 10. Solubility comparisons can be made by using computer-based spreadsheets. By using the resin solubility data and solvent solubility parameters to determine the degree of resin solubility in the solvent, one can develop a list of likely solvent blends that can be verified by laboratory scale testing. Figure 2 illustrates the idealized spherical solubility envelope for a polymer. The total solubility parameter 5, of a material is a point in the three-dimensional space where the three partial Hansen solubility parameters intersect. If the calculated radius of interaction of the solvent and resin combination is less than the radius of the resin solubility sphere, then the solvent will most likely dissolve the resin and the solvent s solubility point will lie within the solubility sphere of the resin. A poor resin solvent combination will have a solubility point outside of the resin envelope. Application of the Hansen solubility theory will shorten the time and effort needed for solvent selection and substitution. 

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