Comparison and conclusions

The simple Flory-Huggins %-function, combined with the solubility parameter approach may be used for a first rough guess about solvent activities of polymer solutions, if no experimental data are available. Nothing more should be expected. This also holds true for any calculations with the UNIFAC-fv or other group-contribution models. For a quantitative representation of solvent activities of polymer solutions, more sophisticated models have to be applied. The choice of a dedicated model, however, may depend, even today, on the nature of the polymer-solvent system and its physical properties (polar or non-polar, association or donor-acceptor interactions, subcritical or supercritical solvents, etc.), on the ranges of temperature, pressure and concentration one is interested in, on the question whether a special solution, special mixture, special application is to be handled or a more universal application is to be foxmd or a software tool is to be developed, on munerical simplicity or, on the other hand, on numerical stability and physically meaningftd roots of the non-linear equation systems to be solved. Finally, it may depend on the experience of the user (and sometimes it still seems to be a matter of taste). 

Equation-of-state approaches are preferred concepts for a quantitative representation of polymer solution properties. They are able to correlate experimental VLE data over wide ranges of pressure and temperature and allow for physically meaningftd extrapolation of experimental data into unmeasured regions of interest for application. Based on the experience of the author about the apphcation of the COR equation-of-state model to many polymer-solvent systems, it is possible, for example, to measure some vapor pressures at temperatures between 50 and 100 C and concentrations between 50 and 80 wt% polymer by isopiestic sorption together with some infinite dilution data (limiting activity coefficients, Henry s constants) at temperatures between 100 and 200 C by IGC and then to calculate the complete vapor-liquid equilibrium region between room temperature and about 350 C, pressures between 0.1 mbar and 10 bar, and solvent concentration between the common polymer solution of about 75-95 wt% solvent and the ppm-region where the final solvent and/or monomer devolatilization process takes place. Equivalent results can be obtained with any other comparable equation of state model like PHC, SAFT, PHSC, etc. 

The quality of all model calculations with respect to solvent activities depends essentially on the careful determination and selection of the parameters of the pure solvents, and also of the pure polymers. Pure solvent parameter must allow for the quantitative calculation of pure solvent vapor pressures and molar volumes, especially when equation-of-state 

1 Wen Hao, H. S. Elbro, P. Alessi, Polymer Solution Data Collection, Pt.l Vapor-Liquid Equilibrium, Pt2 Solvent Activity Coefficients at Infinite Dilution, Pt. 3 Liquid-Liquid Equilibrium, DECHEMA Chemistry Data Series, Vol. XIV, Pis. 1,2+3, DECHEMA, Frankfiirt/M., 1992. 

Danner, M. S. High, Handbook of Polymer Solution Thermodynamics, DIPPR, AIChE, New York, 1993. 

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To adjust (normalize) the data for biases that may have arisen during the technical process thereby ensuring that meaningful biological comparisons and conclusions can be made... 

The Spirit is the viewing, cognizant and the judging principle. Its activity consists of the formation of concepts, comparisons and conclusions. It is the principle of the consciousness, the reflection and the apperception, as well as the recollection. 

Data handling mathematical or statistical analysis of quantitative data to provide reliable comparisons and conclusions. 

Although taking actual current draw and timing measurements deliver the more realistic figures when compared to simulation or numbers provided in data sheets, the downside is that for this prototype the results will be anecdotal and restricted to one particular platform. However, the presented comparisons and conclusions should be still indicative for many wearable sensors, since the platform and its micro controller follow the traditional design of others (for instance, the miao controller has similar features and properties to those in [10], or the same sensor as in [7]). 

The results of the investigations of ternary R-M-Al systems, where M is a metal from the 2-5th periods are briefly summarized in table 7. It is difficult to make a completely correct comparison and conclusions about total number of ternary compounds formed, because of many partial investigations of the phase diagrams. Nevertheless, one can see, that maximum number of ternary compounds formed occurs with Ni and Cu. 

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