Physicochemical investigations of polyethylene glycols with N, N dimethylacetamide (original) (raw)
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Ultrasonic investigations of water mixtures with polyethylene glycols 200, 400 and ethylene glycol
Journal of Molecular Structure, 2005
Ultrasonic velocities and densities were measured in the mixtures of water with ethylene glycol (EG) and polyethylene glycols in the temperature range from 291.15 to 303.15 K. Adiabatic compressibilities were calculated from Laplace's equation based on the experimental results obtained. Variations of these values with concentration and temperature were studied. Structural interactions and the formation of a compact pseudostable structure at very low concentrations of ethylene glycol and polyethylene glycols were observed. The plots of the adiabatic compressibility versus the mole fraction of PEG-s and EG display two characteristic points at low concentrations: the intersection of the isotherms and their minimum. Such relations between adiabatic compressibility, concentration and temperature are usually attributed to the formation of pseudo-stable molecular structures. To formulate a model of local structures present in the investigated molecular systems it is indispensable to get an insight into hydration of molecules and the formation of hydrogen bonds. Therefore, the attention was focused particularly on these problems.
J Mol Struct, 2005
Ultrasonic velocities and densities were measured in the mixtures of water with ethylene glycol (EG) and polyethylene glycols in the temperature range from 291.15 to 303.15 K. Adiabatic compressibilities were calculated from Laplace's equation based on the experimental results obtained. Variations of these values with concentration and temperature were studied. Structural interactions and the formation of a compact pseudostable structure at very low concentrations of ethylene glycol and polyethylene glycols were observed. The plots of the adiabatic compressibility versus the mole fraction of PEG-s and EG display two characteristic points at low concentrations: the intersection of the isotherms and their minimum. Such relations between adiabatic compressibility, concentration and temperature are usually attributed to the formation of pseudo-stable molecular structures. To formulate a model of local structures present in the investigated molecular systems it is indispensable to get an insight into hydration of molecules and the formation of hydrogen bonds. Therefore, the attention was focused particularly on these problems.
Journal of Molecular Liquids, 2018
From the measurements of density and speed of sound, the apparent molar properties and the partial molar properties have been determined to study the interactions of two polyethylene glycols i.e. polyethylene glycol 400 and polyethylene glycol 4000 in aqueous solutions of sorbitol at experimental pressure p = 0.1 MPa and temperatures T = (288.15-318.15) K. Evaluation of partial molar volume (), apparent molar volume () and partial molar volumes of transfer (Δ) is done using density measurements. For the determination of partial molar isentropic compression (,), apparent molar isentropic compression (,), and partial molar isentropic compression of transfer (Δ ,), the ultrasonic speed measurements have been utilized. The limiting apparent molar expansibilities (0) and its first order derivatives (0 ⁄) are also calculated. Further, with the aid of partial molar isentropic compression of transfer and partial molar volumes of transfer, pair and triplet coefficients are determined. Through the scrutiny of these evaluated parameters, the results are elucidated based upon contending patterns of physicochemical interactions of co-solutes and solvents prevailing in present ternary liquid mixtures.
Journal of Chemical & Engineering Data, 2017
The improved isopiestic method was used to measure 1-propanol activity data for several binary mixtures of 1-propanol + poly(propylene glycol) 400 (PPG400)/ poly(propylene glycol) 725 (PPG725)/poly(propylene glycol) 1025 (PPG1025) at 298.15 K. The effect of polymer molar mass was studied on the solvent activity and vapor pressure of the studied systems. The results indicate that solvent activity increases with the increasing of the polymer molar mass. These data have been correlated with different activity models including Flory−Huggins (FH), modified Flory−Huggins, NRTL, NRF-NRTL, Wilson, and NRF− Wilson models. The obtained values of standard deviations for the models represent that modified Flory−Huggins model have good agreement with the experimental data. The apparent specific volume, excess specific volume, isentropic compressibility, isentropic compressibility increments, and apparent specific isentropic compressibility quantities were obtained with use of density and speed of sound data in the 1-propanol + poly(propylene glycol) 400/poly(propylene glycol) 725 systems at T = 288.15 to 318.15 K which supplies the strong solute−solvent interactions and more compatibility between 1-propanol with PPG400 rather than the other polymers.
Ultrasonic Investigation of Pseudo-Stable Structures in Aqueous Mixtures of Polyethylene Glycol
2013
The velocity of ultrasound (c) and the density (ρ) have been measured in mixtures of water and polyethylene glycol (PEG) in the temperature range from 288.15 to 328.15 K. Based on the data obtained, the adiabatic compressibility coefficient (βad) has been calculated from Laplace’s equation. The variations of c, ρ and βad with concentration (μ: mole fraction) and temperature have been studied. Structural interactions and the formation of a compact pseudo-stable structure in the region of a very low polyethylene glycol concentration have been reported. The structure built in these mixtures cannot be a liquid clathrate-like hydrate neither type I nor type I
Journal of Chemical Thermodynamics, 2007
The speed of sound and density measurements in water, methanol, and benzene solutions for the solutes PEG-400, PEG-1000, and PEG-4000 at T = 298.15 K (0.05 to 0.5 mol AE kg À1 ) are reported. The data obtained are used to calculate thermodynamic parameters such as adiabatic (isentropic) compressibility of solutions (b ad ), apparent molar volume (/ V ) and apparent molar compressibility (/ K ) for solute molecules in all the solvent media. The limiting partial molar volume ð/ V Þ and limiting partial molar compressibility ð/ K Þ of solute molecules are used to estimate volume of transfer and compressibility of transfer for PEG molecules from methanol to aqueous and benzene to aqueous media. The high observed negative ð/ K Þ values in methanol are interpreted in terms of breakdown of one-dimensional H-bonded structure of methanolic molecules. The (/ K Þ values observed in water although negative but of small magnitude as compared to salts in water. Attempt is made to estimate hydration number for these molecules in aqueous solutions by applying Shiio's method and it is observed that PEG-4000 is hydrated most. These results are discussed in terms of solute-solvent and hydrophobic interactions and effects due to conformational characteristic of high molecular weight glycol molecules.
Journal of Chemical & Engineering Data, 2018
In this work, some of the thermodynamic properties of binary {1propanol + poly(ethylene glycol) dimethyl ether (PEGDME)} mixtures were studied. The activity of 1-propanol was determined in (1-propanol + PEGDME) systems with polymer molar masses of 250 and 500 g•mol −1 by the use of isopiestic method at 298.15 K. The effect of the polymer molar mass on the solvent activity and also vapor pressure depression was discussed. More vapor pressure lowering is obtained when we use PEGDME with a molar mass of 500 g•mol −1. The obtained solvent activity data were correlated with the Flory−Huggins, modified Flory−Huggins, nonrandom two liquid (NRTL), nonrandom factor (NRF)-NRTL, Wilson and NRF-Wilson models. The interaction parameter obtained from the Flory−Huggins model for PEGDME500 is less than that for the PEGDME250, indicating that the solvent activity has been reduced by increasing the molar mass of polymer. This result leads to an increase in the interaction between the solvent and the polymer by increasing the polymer molar mass. Measurements of the density and speed of sound were also performed at T = (298.15 to 318.15) K for the mentioned systems. From these data, the excess molar volumes, isentropic compressibility deviations, and deviation in speed of sound were calculated; and it was found that excess molar volumes and isentropic compressibility deviations are decreased with increasing temperature. The obtained values of excess molar volumes for PEGDME500 are more negative. These results supply stronger packing effects in the 1-propanol with the PEGDME500 system rather than in the system with PEGDME250. The obtained excess and deviation values were also satisfactorily fitted to the Redlich−Kister and Ott et al. equations
Nucleation and Atmospheric Aerosols, 2022
In the present study, the combination of volumetric and acoustical studies is used to investigate the interactions of ethylene glycol, diethylene glycol, and triethylene glycol with sorbitol as a function of temperature. Densities and ultrasonic velocities of ethylene, diethylene, and triethylene glycol in (0.00, 0.01, 0.03, 0.05) mol•kg −1 aqueous solutions of sorbitol have been measured at temperatures T = (288.15, 298.15, 308.15, 318.15) K and experimental pressure p = 0.1 MPa. With the help of density data, the apparent molar volume V ϕ , the partial molar volume V ϕ o , and the partial molar volumes of transfer ΔV ϕ o , from water to aqueous sorbitol solutions have been computed. The values for partial molar expansibility (∂V ϕ 0 /∂T) p and second order derivative (∂ 2 V ϕ 0 /∂T 2) p have also been determined. From ultrasonic velocity values, apparent molar isentropic compression K ϕ,s , partial molar isentropic compression K ϕ,s o , and partial molar isentropic compression of transfer ΔK ϕ,s o , are evaluated. The computed values of partial molar volumes of transfer and partial molar isentropic compression of transfer are used to determine the pair and triplet coefficients. The parameters thus obtained have been discussed in terms of solute−solute/solute−solvent interactions prevailing in the present ternary system along with the structure making/structure breaking tendency of glycols in aqueous sorbitol solutions.
Journal of Molecular Liquids, 2010
Viscosity, at T = 293.15 K, 298.15 and 303.15 K, and speed of sound, at 298.15 K, have been measured for the binary mixtures of 2-propoxyethanol (PE) with diethylene glycol (DEG), triethylene glycol (TEG) and tetraethylene glycol (TETRAEG), over the entire composition range. The speeds of sound values were combined with those of our previous results of densities to obtain isentropic compressibilities(κ s ) and their excess counterparts(κ s E ). The experimental data were used to calculate the values of deviation of viscosity (Δη) and speed of sound (δu), and excess energy of activation for viscous flow (ΔG 12 * E ). These parameters, especially excess functions, are found to be quite sensitive toward the intermolecular interactions in the studied liquid mixtures. The excess and deviations of studied functions have been correlated using Redlich-Kister type polynomial equation by the method of least-squares for the estimation of the binary coefficients and the standard errors. The viscosity data were correlated with equations of Hind et al., Grunberg and Nissan, Frenkel, and McAllister.
International Journal of Thermophysics, 2006
In this work, the speed of sound was measured in monoglyme (monoethylene glycol dimethyl ether or MEGDME) and diglyme (diethylene glycol dimethyl ether or DEGDME) in the temperature range 293.15 T /K 353.15 at pressures up to 100 MPa using a pulse echo technique operating at 3 MHz; several thermophysical properties were determined in the same P-T range from these measurements. Furthermore, the density, isothermal compressibility, and isobaric thermal expansion coefficient, determined from volumetric data (direct method) and from acoustic measurements (indirect method) for four glymes have been compared. The comparison was extended to a second-order derivative of density with pressure, namely, the nonlinear acoustic parameter B/A.