Line, azeotropic

In conclusion let us make some remarks concerning the existence of the lines both of the limited and partial azeotropes proposed earlier in the literature and discussed in Sect. 4.5. The realization of the conditions of the limited or partial azeotropy in the course of the terpolymerization process means that the representing point x(p) of the system doesn t leave these azeotropic lines under the change... 

In the literature we found a complete set of reactivity ratios only for eleven systems (nine regular and two irregular) studied by Slocombe [128], Further numerical calculations showed [6, 134] that boundary trajectories (separatrices) lay quite close to the azeotropic lines. It also turned out that for all nine regular systems the separatrices entered a regular binary azeotrope x, while in both... 

We are now in a position to study the series of states of uniform composition which are obtained when T,p and a 2 all vary simultaneously. These three variables are always related by the two equatoms (28.17) it follows therefore that only one of them can be varied independently, so that the states of uniform composition fall on a line called the azeotropic line. The differential relations which this line must satisfy are examined below. ... 

The feed composition is represented by point F in Figure 10.3b. An amount of entrainer is added to the feed, and the mixture is then separated into B and the azeotrope. Line EF represents compositions of mixtures formed by combining the feed with varying amounts of the entrainer. In order to separate the mixture into pure B and the azeotrope, the combined mixture must have a composition that lies on a straight line joining B and Z. Thus, the combined feed composition should correspond to point Fc, the intersection of BZ and EF. 

For example, in the absence of an azeotrope (the 45° line is the azeotropic line for which F =/i), and when Mj is more reactive than M2 (i.e., r greater than 1 and r2 less than 1), the ICC will decrease in Mj with an increase in conversion. The extent of composition drift depends on the ratio (rfr2), the initial monomer composition, and the monomer conversion level. 

Exceptions to these general rules about behaviour in the critical region occur at special points on a binary mixture critical line - examples are extrema in pressure or temperature, points where azeotrope lines join critical lines, or double points (intersections of two critical lines). Moreover, in the special higher-order critical points ( tricritical points ) found in systems with a greater number of variables (three- and four-component fluid mixtures He + He), different exponents may be found. ... 

The process diagram shown here is used for such gas condensates whose sour gas content is as least as high as their ammonia content. The NH3/CO2/H2O system exhibits different boiling properties at different pressures. The so-called maximum temperature azeotrope lines, which are defined so that the CO2/NH3 ratios are the same in both phases when the liquid and gas phases are in equilibrium, are shifted in the direction of higher ammonia mixes as pressures are increased. 

Fig. 2.4-15 System C2H4 - CO2-C2H5. Azeotropic lines and lines which indicate the...

The curve does not intercept the ideal azeotrope line, either, in nonideal nonazeotropic copolymerization. But, in contrast to ideal nonazeotropic copolymerization, the curve is no longer symmetrical. In azeotropic nonideal copolymerizations, behavior depends on whether both copolymerization parameters are or are not of the same magnitude. If they are also equal, then, according to Equation (22-15), the azeotropic point must occur at a 1 1 composition ratio, that is, at a mole fraction of 0.5. If the molar fraction is less than 0.5 for monomer B, then the azeotropic ordinate point must be above the 45° ideal azeotropic line because of the tendency to alternate, but the point... 

In terpolymerization, as in bipolymerization, azeotropic mixtures can occur. A calculation for 653 pairs described in the scientific literature gives 731 possible triple sets, of which 36 form an azeotrope 598 quadruple sets with two quadruple azeotropes and 330 possible quintuple sets with only one single quintuple azeotrope forming quintuple set. Azeotrope lines (see Figure... 

Block copolymerization. In block copolymerizations, both parameters are greater than one. The growing ends preferentially add on like monomer units, and the result is more or less long blocks (see Section 22.1.4). The shape of the curves is basically similar to that of nonideal copolymerization (Figure 22-3) but the curve in that case lies above the azeotropic line, while in this case it lies below it. 

In addition to the ternary azeotrope, however, there are also azeotropic lines for each individual monomer. Along these azeotropic lines, the mole fraction of an incorporated component is the same in both the initial monomer mixture and the initial copolymer ... 

In terpolymerizations with MA, where two azeotropic copolymer pairs can be formed, Slocombe described an azeotropic copolymer index. In the method, the monomer-terpolymer composition plots take the form of a triangular coordinate graph. A line connecting the points that represented the composition along the azeotropic line have unique properties, i.e., give clear terpolymers, whereas compositions removed from the line gave increasingly turbid polymers as their distance from the azeotropic line increased. 

Azeotropic Lines. The calculation of liquid-vapour equilibrium includes, in principle, the determination of the conditions for azeotropy. Nevertheless, in practice these are best formulated and tested for in a separate calculation (30). Values of 12 l ss than unity lead correctly to the appearance of azeotropes at high reduced temperatures for the systems CO2 + C2Hg CO2 + C2H4 and CO2 + C2H2 ( ). 

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