Densities of {poly(ethylene glycol) + water} over the temperature range (283.15 to 363.15) K

Densities of {poly(ethylene glycol) [PEG] + water} prepared with PEG average molar mass (200, 400, 600, and 1500) g · mol^?1 have been measured over the entire composition range over the temperature range (283.15 to 363.15) K at 10 K intervals using a density meter based on electromagnetically-induced oscillations of a U-shaped glass tube and an inbuilt Peltier thermostat. The density versus temperature data of (PEG + water) at each composition for all PEGs were fit to a simple quadratic equation: ρ/(g · cm^?3) = ρ₀/(g · cm^?3) + a(T/K) + b(T/K)². Fits were observed to be satisfactory at each composition for all four (PEG + water). The excess molar volumes of (PEG + water) are observed to be negative and significant over the entire composition range for all four (PEG + water). Irrespective of the temperature, the maximum absolute excess molar volumes are observed in the water-rich region of the mixture and are found to decrease with increasing temperature. This is attributed to the presence of strong interactions within the (PEG + water). Specifically, it is proposed to be due to the H-bonding interactions between the PEG and the water molecules within the mixtures.     

Excess enthalpies of ether + alcohol + hydrocarbon mixtures: Binary and ternary mixtures containing dibutyl ether (DBE), 1-butanol and benzene at 298.15 K and 313.15 K

Experimental excess molar enthalpies of the ternary systems dibutyl ether (DBE) + 1-butanol + benzene and the corresponding binary systems at T = 298.15 K and T = 313.15 K at atmospheric pressure are reported. A quasi-isothermal flow calorimeter has been used to make the measurements. All the binary and the ternary systems show endothermic character. The experimental data for the binary and ternary systems have been fitted using the Redlich-Kister equation and the NRTL and UNIQUAC models. The values of the standard deviation indicate good agreement between the experimental results and those calculated from the equations.     

Excess enthalpies of binary and ternary mixtures containing dibutyl ether (DBE), 1-butanol,and heptane at T = 298.15 K and 313.15 K

Experimental excess molar enthalpies of the ternary systems {dibutyl ether (DBE) + 1-butanol + heptane} and the corresponding binary systems at T = 298.15 K and T = 313.15 K at atmospheric pressure are reported. A quasi-isothermal flow calorimeter has been used to make the measurements. All the binary and the ternary systems show endothermic character. The experimental data for the binary and ternary systems have been fitted using the Redlich–Kister equation, the NRTL and UNIQUAC models. The values of the standard deviation indicate good agreement between the experimental results and those calculated from the equations.     

Thermophysical and sonochemical behaviour of binary mixtures of decan-1-ol with halohydrocarbons at (T = 293.15 and 313.15) K

Densities and ultrasonic velocities of binary mixtures of decan-1-ol with 1,2-dichloroethane, 1,2-dibromoethane, and 1,1,2,2-tetrachloroethene have been measured over the entire range of composition at T = (293.15 and 313.15) K and at atmospheric pressure. From these results, the excess molar volumes, molar free volumes, excess molar isentropic compressibilities, limiting excess partial molar volumes, and isentropic compressibilities, intermolecular free lengths, and available volumes by three methods, thermal expansion coefficients, parameters related to space-filling ability, intermolecular free lengths, and molecular radii have been calculated. The experimental ultrasonic velocities have been analyzed in terms of the ideal mixture relations of Nomoto and Van Dael, Jacobson’s free length, Schaaff’s collision factor, Flory’s statistical, and Prigogine–Flory–Patterson theories and thermoacoustical parameters.     

Excess Gibbs energies and excess molar volumes for binary mixtures: (2-pyrrolidone + water), (2-pyrrolidone + methanol), and (2-pyrrolidone + ethanol) at the temperature 313.15 K

Total vapour pressures and excess molar volumes, measured at the temperature 313.15 K, are reported for three binary mixtures (2-pyrrolidone + water), (2-pyrrolidone + methanol) and (2-pyrrolidone + ethanol). The results are compared with previously obtained data for binary mixtures (amide + A), where amide=N-methylformamide, N,N-dimethylformamide and N-methylacetamide, and A= water, methanol, and ethanol.     

Excess molar enthalpies of the ternary mixture n-propanol + n-propyl acetate + water at 313.15 K

Journal of Thermal Analysis and Calorimetry - Excess molar enthalpies, H m E , for the ternary mixture n-propanol (n-PrOH) + n-propyl acetate (n-PrOAc) + water...     

Solubility of gallic acid in liquid mixtures of (ethanol + water) from (293.15 to 318.15) K

The solubility of gallic acid in (water + ethanol) binary solvents was determined from (293.15 to 318.15) K at atmospheric pressure using a thermostatted reactor and UV/vis spectrophotometer analysis. The effects of binary solvents composition and temperature on the solubility were discussed. It was found that gallic acid solubility in (water + ethanol) mixed solvents presents a maximum-solubility effect. Two empirical equations were proposed to correlate the solubility data. The calculated solubilities show good agreement with the experimental data within the studied temperature range. Using the experimentally measured solubilities, the thermodynamic properties of dissolution of the gallic acid such as Gibbs energy (Δ_solG°), molar enthalpy of dissolution (Δ_solH°), and molar entropy of dissolution (Δ_solS°) were calculated.     

Mean activity coefficients of NaCl in (sodium chloride + sodium bicarbonate + water) fromT = (293.15 to 308.15) K

The mean activity coefficients of NaCl in (sodium chloride  +  sodium bicarbonate  +  water) were determined experimentally in the temperature range 293.15 K to 308.15 K at four NaHCO₃molality fractions (0.1, 0.3, 0.5, and 0.7). The measurements were made with an electrochemical cell, using a Na ⁺ glass ion-selective electrode and a Cl ⁻ solid-state ion-selective electrode. The experimental values reported by Butler and Huston are found to be higher than those calculated from the Pitzer equation using the existing parameters while the experimental results of this work are close to the calculated values, up to an NaHCO₃molality fraction of 0.5. At the NaHCO₃molality fraction of 0.7, the experimental data are much lower than the calculated values, implying that the interference of HCO₃ ⁻ on the Na ⁺ glass ion-selective electrode can only be neglected up to a molality fraction of NaHCO₃of 0.5, an observation which is consistent with that of Butler and Huston.     

Experimental investigation of the vapour–liquid equilibrium of binary and ternary mixtures containing dibutyl ether (DBE), cyclohexane and toluene at 313.15 K

New vapour–liquid equilibrium data for binary and ternary mixtures formed by dibutyl ether (DBE), toluene and cyclohexane at 313.15 K have been measured. A static method using an isothermal total pressure cell (Van Ness’ technique) has been employed. The systems studied presented a slight deviation from ideal behaviour. None of them show azeotrope. The VLE data have been satisfactorily correlated with the equations of Margules, Wilson, NRTL and UNIQUAC for binaries and Wohl expansion, Wilson, NRTL and UNIQUAC for the ternary system. Predictions with UNIFAC group contribution methods are included.     

Volumetric properties of binary mixtures of N-ethylformamide with tetrahydrofuran, 2-butanone,and ethylacetate from T = (293.15 to 313.15) K

Densities of binary liquid mixtures of N-ethylformamide (NEF) with tetrahydrofuran (THF), 2-butanone (B), and ethylacetate (EA) were measured at temperatures from (293.15 to 313.15) K and at atmospheric pressure over the whole composition range. Excess molar volumes, V^E, have been obtained from values of the experimental density and were fitted to the Redlich–Kister polynomial equation. The V^E values for all three mixtures are negative over the entire composition and temperature ranges. The V^E values become more negative as the temperature increases for all binary mixtures studied. Other volumetric properties, such as isobaric thermal expansion coefficients, partial molar volumes, apparent molar volumes, partial molar excess volumes and excess thermal expansions have been calculated.     

(Vapour + liquid) equilibrium in (N,N-dimethylacetamide + ethanol + water) at the temperature 313.15 K

Total vapour pressures, measured at the temperature 313.15 K, are reported for the ternary mixture (N,N-dimethylacetamide + ethanol + water), and for binary constituent (N,N-dimethylacetamide + ethanol). The present results are also compared with previously obtained data for (amide + ethanol) binary mixtures, where amide = N-methylformamide, N,N-dimethylformamide, N-methylacetamide, 2-pyrrolidinone, and N-methylpyrrolidinone. We found that excess Gibbs free energy of mixing for binary (amide + ethanol) mixtures varies roughly linearly with the molar volume of amide.     

Excess enthalpies of ternary mixtures of (oxygenated additives + aromatic hydrocarbon) mixtures in fuels and bio-fuels: (Dibutyl-ether + 1-propanol + benzene), or toluene,at T = (298.15 and 313.15) K

New experimental excess molar enthalpy data of the ternary systems (dibutyl ether + 1-propanol + benzene, or toluene), and the corresponding binary systems at T = (298.15 and 313.15) K at atmospheric pressure are reported. A quasi-isothermal flow calorimeter has been used to make the measurements. All the binary and ternary systems show endothermic character at both temperatures. The experimental data for the systems have been fitted using the Redlich–Kister rational equation. Considerations with respect the intermolecular interactions amongst ether, alcohol and hydrocarbon compounds are presented.     

Determination of preferential interaction parameters by multicomponent diffusion. applications to poly(ethylene glycol)-salt-water ternary mixtures

Poly(ethylene glycol) (PEG) is a hydrophilic nonionic polymer used in many biochemical and pharmaceutical applications. We report the four diffusion coefficients for the PEG-KCl-water ternary system at 25 degrees C using precision Rayleigh interferometry. Here, the molecular weight of PEG is 20 kg mol(-1), which is comparable to that of proteins. The four diffusion coefficients are examined and used to determine thermodynamic preferential interaction coefficients. We find that the PEG preferential hydration in the presence of KCl is 1 order of magnitude larger than that previously obtained under the same conditions for lysozyme, a protein of similar molecular weight. In correspondence, the coupled diffusion in the PEG case was greater than that observed in the lysozyme case. We attribute this difference to the greater exposure of polymer coils to the surrounding fluid compared to that of globular compact proteins. Moreover, we observe that the PEG preferential hydration significantly decreases as salt concentration increases and attribute this behavior to the polymer collapse. Finally, we have also employed the equilibrium isopiestic method to validate the accuracy of the preferential interaction coefficients extracted from the diffusion coefficients. This experimental comparison represents an important contribution to the relation between diffusion and equilibrium thermodynamics.     

Excess volumes of mixing in (N,N-dimethylacetamide + methanol + water) and (N,N-dimethylacetamide + ethanol + water) at the temperature 313.15 K

Precise excess volumes of mixing measurements at T = 313.15 K are reported over the whole composition range for binary mixtures: (N,N-dimethylacetamide + water), (N,N-dimethylacetamide + methanol), (N,N-dimethylacetamide + ethanol) and for the ternary mixtures (N,N-dimethylacetamide + methanol + water) and (N,N-dimethylacetamide + ethanol + water). For all the systems, large negative deviations from ideality are observed. The binary results have been fitted using the Redlich–Kister type polynomial. The possibility of predicting the ternary results from the binary ones was examined.     

Phase separation in mixtures of poly(ethylene glycol monomethylether) and poly(propylene glycol) oligomers

Time-resolved light scattering was employed to investigate kinetics of phase separation in mixtures of poly (ethylene glycol monomethylether) (PEGE)/poly (propylene glycol) (PPG) oligomers. Phase diagrams for PEGE/PPG of varying molecular weights were established by means of cold point measurements. The oligomer mixtures reveal an upper critical solution temperature (UCST). Several temperature quench experiments were carried out with a 60/40 PEGE/PPG blend by rapidly quenching from a single phase (69°C) to two-phase temperatures (66–61°C) at 1°C intervals. As is typical for oligomer mixtures, the early stage of spinodal decomposition (SD) was not detected. The kinetics of phase decomposition was found to be dominated by the late stage of SD. Time-evolution of scattering intensity was analyzed in accordance with nonlinear and dynamical scaling theories. The time dependence of the peak intensity I_m and the corresponding peak wavenumber q_m was found to follow the power-law {I_m(t)? t^α, q_m(t)? t^-β} with the values of α = 3 ± 0.3 and β = 1 ± 0.2, which are very close to the values predicted by Siggia. This process has been attributed to a coarsening mechanism driven by surface tension. In the temporal scaling analysis, the structure function reveals university with time, suggesting self-similarity. Phase separation dynamics in 60/40 PEGE/PPG resembles the behavior predicted for off-critical mixtures.