Petr Pacák

Polarizability and molecular radius of dimethyl-sulfoxide and dimethylformamide from refractive index data

Densities and refractive indicies of dimethylsulfoxide and dimethylformamide were measured at various temperatures and wave-lengths. Polarizabilities and molecular radii were calculated on the basis of Böttchers theory of electric polarization and compared with the molecular radii evaluated from the molar volumes of the liquids and from geometrical considerations.

The phase diagram and supercooling conditions for the Ca(NO3)2−CaCl2−H2O system

The liquidus temperature and induction periods were measured for crystallization in a system of calcium nitrate, calcium chloride, and water over a concentration range of 5–20 mole% Ca(II), i.e., R=4–18 [R=moles H2O/moles Ca(II)] and ycl=0–1 [ycl=moles Cl−/moles (NO3−+Cl−)]. A ternary phase diagram was constructed, and qualitative dependences of the supercooling at which the solution began to crystallize on the system composition were found. A wide range of stability toward crystallization was found for solutions withR=4–10 and ycl=0–0.7 The relationships between the system stability toward crystallization and the viscosity, glass-transition temperature, and the liquidus temperature are discussed.

The Liquidus and Glass Transition Temperature of the Silver Nitrate—Dimethylsulphoxide—Water System

— 60 mol% silver nitrate at various compositions of mixed solvent. The monosolvate of silver nitrate is formed and was isolated in crystalline form. The glass transition temperatures (Ts) of this system were also studied. It was found that, at a constant composition of the mixed solvent, the dependence of the glass transition on the salt concentration can be approximated by a linear relationship in the same way as that on the dimethylsulphoxide content in the solvent at a constant salt concentration in solution.

Liquidus and glass transition temperatures of the ammonium nitrate-dimethylsulfoxide-water system

The liquidus temperature was measured in the ammonium nitrate-dimethylsulfoxide-water system over in the concentration range 0–60 mole% ammonium nitrate. The probable formation of the NH4NO3·nDMSO solvate with n=1.3–1.5 and the mixed solvate NH4NO3·DMSO·H2O at 30 mole% ammonium nitrate and a DMSO:H2O ratio of 4∶1 are indicated. The glass transition temperatures Tg were measured over a salt concentration range of 0–50 mol% ammonium nitrate and at various compositions of the mixed solvent (yDMSO=0.1–0.9 mole fraction). At a constant mixed solvent composition, the dependence of the glass transition temperature on the salt concentration can be approximated by a linear relationship, as can its dependence on the DMSO content in the solution at constant salt concentration. The glass-forming composition regions were found and the limits of this region are discussed.