Search results for "Composition dependence"
showing 3 items of 3 documents
Thermodynamic Interaction Parameters for the System Water/NMMO Hydrate
2008
Vapor pressures of water were measured for aqueous solutions of N-methyl-morpholine N-oxide (NMMO) at 80, 90 and 100 degrees C. The Flory-Huggins interaction parameters, chi, calculated from these data as a function of phi, the volume fraction of NMMO, are negative at all concentrations; at low phi, they decrease by more than a factor of 2 as T is raised, whereas they remain almost unchanged as phi approaches unity. Accordingly, the heat of mixing is pronouncedly endothermal at low NMMO concentrations but close to athermal at low water content. The composition dependence of chi can be equally well described by the Redlich-Kister equation and by an approach subdividing the mixing process int…
The resistivity and thermopower of amorphous Mg-Zn alloys
1983
The resistivity and thermopower of amorphous Mg-Zn alloys have been computed as a function of temperature and composition. The diffraction model incorporating the dynamical partial structure factors is applied. The effect of the electron mean free path is investigated. The authors find that the resistivity is well described by the model, and that the inclusion of the mean free path does not change the results considerably. In the case of thermopower the diffraction model turns out to be inadequate: it gives a composition dependence which is against the experimental evidence. This suggests that there exists another scattering mechanism, which is not accounted for by the diffraction model. Th…
Vapor Pressures of Polymer Solutions and the Modeling of Their Composition Dependence
2009
Equilibrium vapor pressures, p, are reported for the systems tetrahydrofuran + poly(vinyl methyl ether) and tetrahydrofuran + polystyrene at 20, 40, and 60 °C. These data plus information from the literature serve to demonstrate that the composition dependence of p can be modeled quantitatively for polymer solutions in thermodynamically very different solvents by means of three, physically meaningful parameters.