Interaction parameter obtained

It is important to note, that the interaction parameters between the components (two per binary) were estimated solely from binary phase equilibrium data, including low-pressure VLE data for the binary acetone - water no ternary data were used in the fitting. The values of the interaction parameters obtained are shown in Table III. 

Although Procedure C is a good predictive method, it should not be used as a substitute to reducing good experimental data to obtain activity coefficients. In general, higher accuracy can be obtained from empirical models when these models are used with binary interaction parameters obtained from experimental data. 

When Oi deviates significantly from unity, as would be the case when not all of the compounds are completely miscible, then separate computations for Oi are required. This can be accomphshed by using some of the recently estabhshed models (55) which compute the a/s by using group interaction parameters obtained from data reduction. 

Schreiber and collaborators (44,4S) reported such compariscms of interaction parameters obtained by GC and static methods for poly(dimethyl siloxane) (44) and natural mbber (45). A summary of their results for hydrocarbon K>hites in poly(di-methyl siloxane) is given in Table 3 for both x (x ) d X12 interaction parameters. 

Terms B a, B ca Z, Cca, F, cc cc corresponding terms for anion pairs) are functions given in full by Pitzer (4) and others (1) and therefore not reproduced here. The B and C functions incorporate ion interaction parameters obtained from pure electrolyte data, (P ca. P ca p ca C ca)- Functions cc those for anions, contain parameters (0cc and 0aaO for interactions between ions of like sign and an unsymmetrical mixing term. The parameters Ycc a d Vcaa account for interactions between one ion of one sign, and two dissimilar ions of opposite sign. 

Table 6.7presents the values of binary interaction parameters obtained by regression, and used in the back calculation of liquid activity coefficients. 

Experimentally obtained data on the thermodynamic properties of the C-Fe-W alloys are very scarce. The effect of tungsten on flie activity of carbon in liquid iron alloys has been studied by [1959Fuw, 1960Fuw, 1960Mor]. The interaction parameter obtained at 1560°C in low-carbon melts by [1959Fuw] was reported as = -2.3. This value was not referred to a fixed carbon concentration. The summarized results of [1959Fuw] were mentioned in the review of [1963Ell]. 

PBSA and PVPh are miscible crystalline/amorphous polymer blends. Miscibility of PBSA/PVPh blends was evidenced by the single composition-dependent glass-transition temperature over the entire blend compositions. The negative polymer-polymer interaction parameter, obtained from the melting depression of PBSA, indicates that PBSA/PVPh blends are thermodynamically miscible. 

The values of interionic interaction parameters, obtained from the spectral, calorimetric, and magnetic investigations of different lanthanide compounds, are given in table 11. The relative interionic positions are specified by the vectors ry in the crystallographic coordinate systems. 

The classic rigid lattice model still proves to be a valuable tool for predictive calculations of phase stability in polymer blends. It depends on the required accuracy whether the simple model needs improvement. Miscibility behaviour of blends containing statistical copolymers do not seem to require such Improvements since values of pair-interaction parameters obtained on one system appear to be transferable to another, fig.6 bears witness of this welcome feature. A similar transferability was observed previously in an analysis of critically demixing poly(styrene) solutions in n-alkanes and n-alcohols varying in number of carbon atoms [31]. The data allowed extraction of the end/middle group interaction function for n-alkanes that correctly predicted the lower critical miscibility behavior of n-alkane /poly(ethylene) systems. 

TABLE 12.1 Hyperfine Interaction Parameters Obtained from Zero-Field Conventional Fe Mossbauer Parameters Fe NFS Spectra Compared with the ... 

Spectroscopic Methods.—Nuclear Magnetic Resonance (n.m.r.). Cohen-Addad and Ruby comment that thermodynamic polymer-solvent interaction parameters obtained from n.m.r. data should be contrasted with those obtained from other methods in the sense that the former are defined on a molecular scale only. That is, nuclear spins are local probes, sensitive to magnetic interactions averaged over volumes of molecular size. N.m.r. methods, therefore, usefully complement other methods in studying underlying statistical mechanical models for polymer-solvent mixtures at equilibrium a comment which has been amplified in relation to polymer blends. ... 

The UNIFAC model defines functional groups, which make up the stractures of compounds. Each frmctional group makes a rrrtique contribution to the compound property. The interaction parameters obtained for a small number of groups using thermodynamically consistent data can be used for mrrlti-component systems. 

Neutron reflection has been used to stu die interfaces between the melt phases of ciystallisable polymers as well as real time interdiffusion of polymers and oligomers. Both systems are experimentally demanding and have required the use of specialised cells and data collection procedures. The interfacial widths for a number of polymer systems have been determined and the Flory Huggins interaction parameters obtained. In addition, the interdiffiision process has been followed for a polystyrene-polystyrene system above its Tg and also for a polystyrene-oligostyrene in-situ in real time using very rapid reflectivity scans. 

Fig. 3 Interaction parameters obtained from the data in Fig. 1 by Eq. (5), such as the strength J of segregation between water and decane, the amphiphilicity L < 0 of surfactant molecules and the critical concentrations (j>s of surfactant...

Fig. 11 Isochoric phase diagram for the system n-C4/l,4-PB [50], The measured data points are drawn as stars and those calculated by means of the interaction parameters obtained from the vapor pressure measurements as circles...

It should be noted that the segmental interaction parameter obtained from d-SPS/h-APS mixtures includes not only the tacticity effect but also the isotopic effect, that is, the interaction between deuterated and hydrogenous polymers [10]. Therefore, a comparison of the results with the literature on... 

Continuing in the line of our studies of chemical reactivity in solution using the MD/ESIE method [4], in the present work we apply our methodology to methyl formate hydrolysis in aqueous solution. We show how the results are improved when the solvent is not described as a continuum but as a discrete system formed by numerous water molecules interacting with the solutes (reactant and transition state). The method differs from that used by other workers [5] in that it uses potentials with interaction parameters obtained from ab initio calculations, and free-energy curves are used to calculate the activation energy. 

Table 7.7 Ion interaction parameters obtained from solubility of brucite data in chloride media.

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