Apparent Specific Volume Research Articles

Density, viscosity, and refractive index of mono-, di-, and tri-saccharides in aqueous glycine solutions at different temperatures

Density, ρ, viscosity, η, and refractive index, nD of glucose, sucrose, and raffinose have been measured in 0.015 m aqueous glycine at 298.15, 303.15, 308.15, and 313.15K. From these experimental data, apparent molar volumes, Vϕ, apparent specific volumes, Vϕ,sp as a function of the concentration of solutes, the standard partial molar volume, Vϕ0, transfer volume from water to aqueous glycine solutions, ΔVϕ(tr)0, and partial molar expansibility of solute, Eϕ0 have been calculated for glucose, sucrose and raffinose in aqueous glycine solutions. Falkenhagen coefficient A and Jones–Dole coefficient B, free energies of activation of viscous flow per mole of solvent, Δμ10#, and solute, Δμ20#, enthalpy, ΔH0#, and entropy, ΔS0# of activation of viscous flow have been evaluated by using viscosity data. The molar refraction has been calculated by using measured refractive index data. Results have been explained in terms of solute–solute and solute–solvent interactions.

Effect of protic ionic liquid on the volumetric properties and taste behaviour of sucrose

The volumetric properties and taste behaviour of sucrose in aqueous solutions of a protic ionic liquid (3-hydroxypropylammonium acetate) have been studied at temperatures, T=(293.15–318.15)K and at atmospheric pressure. Apparent molar volumes, V2,ϕ, apparent specific volumes, ASV, apparent molar isentropic compressibilities, Ks,2,ϕ, and apparent specific isentropic compressibilities, ASIC, were calculated from measured density, ρ and speed of sound, u data. Partial molar volumes, V2°, and partial molar isentropic compressibilities, Ks,2° at infinite dilution, transfer parameters (ΔtV2° and ΔtKs,2°), expansion coefficients, [(∂V2°/∂T)P and (∂2V2°/∂T2)P], interaction coefficients, (YAB and YABB) and hydration numbers, Nw, were also evaluated and discussed in terms of solute–cosolute interactions. Further, the effect of protic ionic liquid on the taste behaviour of sucrose has been discussed from ASV and ASIC parameters, as these parameters, which are sensitive to solvation behaviour of solute, are divided into four basic taste qualities occupying certain ranges.

Comparative study of the physicochemical properties of aqueous solutions of the hydrocarbon and fluorocarbon surfactants and their ternary mixtures

Speed of sound and density of aqueous solutions of hydrocarbon p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethyleneglycols) (Triton X-100 (TX100), Triton X-165 (TX165)) and fluorocarbon (Zonyl FSN-100 (FSN100), Zonyl FSO-100 (FSO100)) surfactants as well as their ternary mixtures were measured at 293K. Taking into account these values and the literature data of the surface tension and viscosity of the studied systems, the values of the isentropic compressibility, apparent specific adiabatic compressibility, hydration number, apparent specific volume and Jones Dole’s A and B-coefficients were determined. For the systems containing FSO100 also the values of dB/dT were determined on the basis of the values of viscosity measured at different temperatures. Next, the calculated thermodynamic properties have been discussed in the term of intermolecular interactions between the components of the mixtures.

Densitometry and ultrasound velocimetry of hyaluronan solutions in water and in sodium chloride solution

The densities of hyaluronan solutions in water and 0.15M NaCl were measured in the temperature range from 25 to 50°C for the hyaluronan molecular weights from 10 to 1750kDa. The density increased linearly with concentration and decreased with temperature. The data were fitted by the equation describing the density as a linear function of concentration and a quadratic function of temperature. The effect of molecular weight was negligible and thus single equation was sufficient to describe all data. The apparent and partial specific volumes were calculated from the density data including their extrapolated values to infinite dilutions. The measurement of ultrasound speed in the same solutions under the same conditions enabled to calculate the compressibility and its dependence on concentration and temperature. The compressibility decreased with both the concentration and the temperature but the effect of the concentration was only slight mild. The compressibility was used to estimate the hydration numbers which slightly decreased with increasing temperature and concentration. The addition of NaCl changed only the numerical values of density and ultrasound velocity while not changing the character of their dependence on temperature and concentration. Measured and calculated data indicate that hyaluronan does not disturb the specific water structure in the studied concentration range and support the idea of the existence of water clusters or nanodroplets hydrating the hyaluronan chains in solution.

Density, Refractive Index, Apparent Specific Volume, and Electrical Conductivity of Aqueous Solutions of Poly(ethylene glycol) 1500 at Different Temperatures

Thermophysical properties of aqueous solutions of poly(ethylene glycol) 1500 g·mol–1 were measured as a function of polymer concentration w = (0.05, 0.10, 0.15, 0.20 and 0.25) and temperature T/K = (288, 293, 298, 303 and 308). Aqueous systems composed of poly(ethylene glycol) are frequently used in processes involving the separation of biological compounds. The density of the solutions varied from (1001.68 to 1042.65) kg·m–3, the refractive index ranged from (1.3377 to 1.3681), the apparent specific volume was between (0.8336 and 0.8528) g·cm–3, and the electrical conductivity varied between (66.22 and 170.29) 10–3 mS·cm–1. Polynomial models for the properties as a function of temperature and poly(ethylene glycol) 1500 g·mol–1 concentration were fitted to the experimental data. Models accounting for combined effects between variables are particularly useful in industrial applications in which physical parameters must be promptly and accurately calculated.

Intermolecular interactions in mixtures of poly (ethylene glycol) with methoxybenzene and ethoxybenzene: Volumetric and viscometric studies

The density and viscosity values of the binary mixtures of {poly (ethylene glycol) (PEG400)+methoxybenzene, or+ethoxybenzene} have been measured at T=(298.15, 308.15, and 318.15)K. From these experimental values, the excess molar volume, apparent specific volume, partial specific volume of solute, partial specific volume of solvent and excess Gibbs free energy of activation have been computed over the entire range of composition at three temperatures. From the experimental data, the thermodynamic functions of activation have been estimated for each binary mixture. The obtained results have been interpreted in light of polymer–solvent interactions and packing effects. The signs of excess molar volume and deviations of excess Gibbs free energy of activation have been used to obtain some information in regard to existence of specific interactions between PEG400 and solvents molecules. The changes in entropy and enthalpy of activation from the initial state to the transition state were also calculated in order to see which one of these functions controls viscous flow process in the studied polymer solutions. The excess molar volume and excess Gibbs free energy of activation values have been adequately fitted to the Redlich–Kister polynomial. Apparent specific volume values were correlated with the suitable equation. The different models proposed for correlating the viscosity of polymer solutions or liquid mixtures (segment-based-Eyring–NRTL, segment-based-Eyring–Wilson, Grunbreg–Nissan, Frenkel, Hind et al., Katti–Chauddhri, Tamura–Kurata, Auslander and McAllister) have also been used to fit the viscosity values.

Solution behaviour and sweetness response of d-Mannitol at different temperatures

The solution properties of d-Mannitol (DM) were studied to explore sweetness response and molecular interactions in aqueous solutions at different temperatures. The density (ρ) and ultrasonic velocity (μ) were measured at 20–45°C using density sound velocity metre (DSA 5000M). The results obtained were used to compute apparent and partial molar volume, apparent specific volumes, partial molar expansibility, apparent molar isentropic compressibility and compressibility hydration number. The partial molar volume (ΦV°) indicates hydrophilic interactions dominating in aqueous solution of DM. The quality of taste has been determined from apparent specific volumes (ASV) data at 20–45°C and 0.04–0.89molkg−1.The apparent molar isentropic compressibility (ΦK(s)) and hydration number (nH) conferred pre-dominance of solute–solvent interactions, whereas partial molar expansibility (ΦE°) and related standards predicted structure making behaviour of DM. This study may provide new insights in elucidation of mechanistic differences between sweeteners and their mode of interactions.

Studies on molecular interactions of some sweeteners in water by volumetric and ultrasonic velocity measurements at T = (20.0–45.0 °C)

Densities and ultrasonic velocity values for aqueous solutions of two sweeteners viz., maltose monohydrate and acesulfame-K have been measured as a function of concentration at 20.0–45.0°C and atmospheric pressure. Solutions of acesulfame-K were treated as electrolyte, while maltose was considered as non-electrolyte. The apparent molar and specific volumes, their isentropic apparent molar and specific compressibilities, as well as their compressibility hydration numbers have been calculated and reported. Negative deviations from Debye–Huckel limiting law of apparent molar volume for acesulfame-K was obtained at given temperatures and can be used as a direct measure of the ion–ion and ion–solvent interactions. Furthermore, apparent specific volumes of the solutes were calculated and it was found that these values of the investigated solutes lie on the borderline between the values reported for sweet substances. The partial molar expansibility, its second derivative values, (∂2V0/∂T2) and thermal expansion coefficient have been estimated.

On the total, apparent partial molar, partial molar, apparent partial specific and partial specific volume of the binary systems

In this article, seven relationships that have been widely used to estimate the dependence of apparent partial specific volume (APSV) with concentration are reviewed and compared with each other. Also, 10 methods to evaluate partial molar volume (PMV) were derived and compared with each other. At null concentrations the values of APMV of all relationships meet each other; therefore all of the above relationships at very low concentrations are useful and estimate values near to each other. However, as the concentration increases the differences also increase. The variation of APMV with molality or mole-fraction of solute is not linear, and therefore any line fitted to the data to get the slope and intercept to estimate PMV is visual approximation and hence it is bias. The values of PMV obtained through APMV values follow the same curvature trend as values of APMV with a positive slope. Whereas the values of PMV calculated from the slope of density versus molality fit-in a perfect straight line with negative slope (in the range of concentration studied). The appropriate concentration unit for PMV and partial specific volume (PSV) is molality, and the combined relationship is the most appropriate way to evaluate PMV. However, other concentration units such as mass per volume and weight fraction as concentration unit are also studied. It was demonstrated that when a combined relationship is used, evaluation of PMV and PSV is easier and exact. Also, the values of PMV extrapolated to zero concentration were compared with the molar volumes of solvent and solute.

Characterization of dynamics in complex lyophilized formulations: II. Analysis of density variations in terms of glass dynamics and comparisons with global mobility, fast dynamics, and Positron Annihilation Lifetime Spectroscopy (PALS)

Amorphous HES/disaccharide (trehalose or sucrose) formulations, with and without added polyols (glycerol and sorbitol) and disaccharide formulations of human growth hormone (hGH), were prepared by freeze drying and characterized with particular interest in methodology for using high precision density measurements to evaluate free volume changes and a focus on comparisons between “free volume” changes obtained from analysis of density data, fast dynamics (local mobility), and PALS characterization of “free volume” hole size. Density measurements were performed using a helium gas pycnometer, and fast dynamics was characterized using incoherent neutron scattering spectrometer. Addition of sucrose and trehalose to hGH decreases free volume in the system with sucrose marginally more effective than trehalose, consistent with superior pharmaceutical stability of sucrose hGH formulations well below Tg relative to trehalose. We find that density data may be analyzed in terms of free volume changes by evaluation of volume changes on mixing and calculation of apparent specific volumes from the densities. Addition of sucrose to HES decreases free volume, but the effect of trehalose is not detectable above experimental error. Addition of sorbitol or glycerol to HES/trehalose base formulations appears to significantly decrease free volume, consistent with the positive impact of such additions on pharmaceutical stability (i.e., degradation) in the glassy state. Free volume changes, evaluated from density data, fast dynamics amplitude of local motion, and PALS hole size data generally are in qualitative agreement for the HES/disaccharide systems studied. All predict decreasing molecular mobility as disaccharides are added to HES. Global mobility as measured by enthalpy relaxation times, increases as disaccharides, particularly sucrose, are added to HES.

Effect of temperature on volumetric and transport properties of ternary poly ethylene glycol di-methyl ether 2000 + poly ethylene glycol 400 + water and the corresponding binary aqueous solutions: Measurement and correlation

The density, speed of sound and viscosity values of {poly ethylene glycol di-methyl ether 2000 (PEGDME2000)+poly ethylene glycol 400 (PEG400)+water}, ((PEGDME2000)+water) and ((PEG400)+water) solutions have been measured at T=(293.15, 298.15, 303.15, 308.15, and 313.15)K. From these measurements, values of the excess molar volume (VmE), excess molar isentropic compression (Ks,mE), excess Gibbs free energy of activation of viscous flow (G*E) and deviation of viscosity (Δη) were calculated. Expressions for VmE and Ks,mE of polymer solutions were obtained by the modified Wilson model for binary and multi-component polymer solutions. The necessary expression for Ks,mE of the polymer NRTL model was also obtained for multi-component polymer solutions. These expressions were used to fit the experimental VmE and Ks,mE data of the investigated systems. Furthermore, the Eyring-modified Wilson and Eyring-NRTL models have been used to correlate the viscosity values of binary and ternary solutions. The apparent specific volumes at infinite dilution values for the binary and ternary solutions were also determined from the density data at dilute range. These values were used to obtain some information regarding the segment–solvent and segment–segment interactions.

Physical characteristics of poly (vinyl alcohol) solutions in relation to electrospun nanofiber formation

Nanofibers prepared from poly (vinyl alcohol) (PVA) using the electrospinning process have received a great deal of attention over the past decade due to their outstanding characteristics and their applicability in the field of biomedicine, coupled with their innovative preparation. However, the success of the electrospinning process depends strongly on the parameters of the source polymer solution. Of these parameters the majority of published papers routinely examine the viscosity, conductivity and surface tension, while other, indeed crucial, physical characteristics are only rarely investigated. In the present work, the emphasis was also on a comprehensive investigation of the bulk and interfacial rheology as well as on the small-angle X-ray scattering (SAXS) of PVA solutions. A detailed analysis revealed rearrangements of the molecules in the solutions depending on the polymer concentration proved by measured surface tension, determined apparent specific volume and radius of gyration. Further, we found out that smooth nanofibers are formed only from those PVA solutions, where properly firm internal polymer structures that can be oriented in the direction of an applied electric field, enable complete polymer elongation during the electrospinning. It is important to note that this is the first time that such an extensive study has been made and, our findings provide a better insight into the physical properties of the solutions for electrospinning as well as their decisive influence on the formation of the nanofibers.

Impact of cosolvent (glucose) on the stabilization of ovalbumin

Proteins are stabilized by glucose against denaturation due to extremes of pH. This was studied by means of density, ultrasonic velocity, viscosity and surface tension measurements in the ovalbumin (5 mg/ml) dissolved in phosphate buffer (pH 2, 5, 7, 9 and 12). Few thermo-acoustical parameters such as adiabatic compressibility, intermolecular free length, acoustic impedance, the partial apparent specific volume and the partial apparent specific adiabatic compressibility were calculated for the said systems. Obtained results suggest that the stabilization of ovalbumin occurs in the presence of glucose through strengthening of hydrophobic interactions supported by other non-covalent interactions and the steric exclusion effect of the cosolvent molecules.

Structure and Interactions of Charged Triblock Copolymers Studied by Small-Angle X-ray Scattering: Dependence on Temperature and Charge Screening

A series of thermo-responsive cationic triblock copolymers composed of methoxy-poly(ethylene glycol) (MPEG, hydrophilic), poly(N-isopropylacrylamide) (PNIPAAM, temperature sensitive), and poly((3-acrylamidopropyl) trimethyl ammonium chloride) (PN(+), cationic) has been investigated as a function of temperature and ionic strength. In the MPEG-b-PNIPAAM-b-PN(+) copolymers, the MPEG block length is constant, and the lengths of the PNIPAAM and PN(+) blocks are varied. The solubility of the PNIPAAM block decreases with increasing temperature, and the triblock copolymer thus provides the possibilities of studying micelles with both neutral and charged blocks in the micelle corona as well as the interplay between these two blocks as the electrostatic interactions are varied by addition of salt. Investigation of the systems by densitometry and small-angle X-ray scattering (SAXS) in a temperature range from 20 to 70 °C gave detailed information on the behavior both below and above the critical micelle temperature (CMT). A clear effect of the addition of salt is observed in both the apparent partial specific volume, obtained from the densitometry measurements, and the SAXS data. Below the CMT, the single polymers can be described as Gaussian chains, for which the repulsive interchain interactions, originating from the charged PN(+) block, have to be taken into account in salt-free aqueous solution. Increasing the salt concentration of the solution to 30 mM NaCl leads to an increase in the apparent partial specific volume, and the electrostatic repulsive interchain interactions between the single polymers vanish. Raising the temperature results in micelle formation, except for the copolymer with only 20 NIPAAM units. The SAXS data show that the polymer with the medium PNIPAAM block length forms spherical micelles, whereas the polymer with the longest PNIPAAM block forms cylindrical micelles. Increasing the temperature further above the CMT results in an increase in the micellar aggregation number for both of the polymers forming spherical and cylindrical micelles. The addition of salt to the solution also influences the aggregates formed above the CMT. Overall, the micelles formed in the salt solution have a smaller cross-section radius than those in aqueous solution without added salt.

Thermodynamics of aqueous solutions of poly ethylene glycol di-methyl ethers in the presence or absence of ammonium phosphate salts

Precise measurements of density and sound velocity at different temperatures ranging from 283.15 to 308.15 K for solutions of PEGDME250, PEGDME500 and PEGDME2000 in water and of PEGDME500 in aqueous solutions of 0.500 mol kg −1 ammonium di-hydrogen phosphate ((NH 4)H 2PO 4) and di-ammonium hydrogen phosphate ((NH 4) 2HPO 4), binodal curves at temperature ranges 293.15–318.15 K for the aqueous PEGDME500 + (NH 4) 2HPO 4, PEGDME500 + (NH 4) 3PO 4, PEGDME2000 + (NH 4)H 2PO 4, PEGDME2000 + (NH 4) 2HPO 4, PEGDME2000 + (NH 4) 3PO 4 and PPG400 + (NH 4) 2HPO 4 two-phase systems, and liquid–liquid equilibrium data at temperature ranges 298.15–318.15 K for the aqueous PEGDME500 + (NH 4) 2HPO 4 and PEGDME2000 + (NH 4) 2HPO 4 two-phase systems have been taken. From the experimental density and sound velocity data, the apparent specific volume, excess specific volume, isentropic compressibility and isentropic compressibility deviation values have been determined and the effect of temperature, charge on the anion of electrolytes and molar mass of PEGDME on the volumetric and compressibility properties of the investigated polymer solutions as well as on the salting-out effect of PEGDMEs produced by ammonium phosphate salts has been studied.

Volumetric, Compressibility, and Viscometric Measurements of Binary Mixtures of Poly(vinylpyrrolidone) + Water, + Methanol, + Ethanol, + Acetonitrile, + 1-Propanol, + 2-Propanol, and + 1-Butanol

The apparent specific volumes and isentropic compressibilities of poly(vinylpyrrolidone) (PVP) in water, methanol, ethanol, acetonitrile, 1-propanol, 2-propanol, and 1-butanol have been obtained at the (288.15 to 313.15) K temperature range at 5 K intervals at atmospheric pressure from measurements of density and speed of sound. The infinite dilution apparent specific volume and isentropic compressibility values of PVP in the investigated solvents have been obtained, and their variations with temperature and type of solvents have also been obtained. The results have been interpreted in terms of the interactions between different solvents and the polymer. In the second part of this work, viscosity measurements have been carried out on the all mentioned solutions at T = (293.15, 298.15, 303.15, 308.15, and 313.15) K at atmospheric pressure. The variations of viscosity with the concentration of polymer, temperature, and type of solvent have been determined. The results have been correlated successfully with the segment-based Eyring−Wilson and nonrandom two-liquid (NRTL) viscosity models. It was found that the Wilson model produces better results than the NRTL model.

Dipole moment and self-association of acesulfame and saccharin in 1,4-dioxane solution at 298.15 K

The density, refractive index, and electrical permittivity of 1,4-dioxane solutions of acesulfame [6-methyl-1,2,3-oxathiazine-4(3H)-one-2,2-dioxide] and saccharin [1,2-benzisothiazole-3(2H)-one-1,1-dioxide] were measured at 298.15 K. From the experimental data the limiting apparent specific volume, refraction, and polarization of acesulfame and saccharin were calculated. The electrical dipole moments of acesulfame and saccharin were estimated according to the Debye, Onsager, and Kirkwood approaches. The association via dipole–dipole interactions of acesulfame and saccharin was treated with the assumption that the dipole moment of dimeric species of acesulfame and saccharin is zero. The dimerization constants and dipole moments of corresponding monomeric species were evaluated. Since the fraction of monomers is close to unity it is worth mentioning that the dimerization effect is rather weak.

Volume Changes Associated with Guanidine Hydrochloride, Temperature, and Ethanol Induced Unfolding of Lysozyme

We studied the guanidine hydrochloride (GdnHCl)-, temperature-, and ethanol-induced unfolding of lysozyme using high-precision densitometric measurements, aiming to characterize and compare the volume changes, Δν(o), accompanying the unfolding of a protein simultaneously by different means, that is, by GdnHCl, temperature, and an organic cosolvent, EtOH. The data obtained are also compared with other means of unfolding, such as high-pressure- and dimethyl sulfoxide (DMSO)-induced denaturation. To aid in interpreting the temperature dependence of the apparent specific volume of lysozyme, we have also carried out pressure perturbation (PPC) and differential scanning calorimetry (DSC) measurements under the same solution conditions. The PPC method allows the detection of very small volume changes with high accuracy. Next to the strong temperature dependence of Δν(o), the volume changes associated with the unfolding of the protein are found to be very sensitive to the type of denaturation. The apparent specific volume decreases upon the heat- and GdnHCl-induced denaturation. The observed volume change for the GdnHCl-induced denaturation is 60% larger (i.e., more negative) than that obtained for thermal denaturation. Conversely, the apparent specific volume increases by an order of magnitude and becomes positive upon ethanol-induced denaturation, similar to the aprotic organic solvent, DMSO. Hence, depending on the type of denaturant (temperature, pressure, chemical denaturants, or cosolvents), positive and negative volume changes of unfolding are found, which can--at least in part--be attributed to the formation of different unfolded state structures (including clustering) of lysozyme. The standard Gibbs energy changes upon denaturation, ΔG(D)(o), for the various perturbation parameters are found to be similar, however, if extrapolated to zero cosolvent concentration.

Viscometric and volumetric study of dilute aqueous solutions of binary and ternary poly(ethylene glycol)/poly(vinyl alcohol) systems at different temperatures

Densities and viscosities of binary and ternary systems of poly(ethylene glycol) (PEG) + H 2O, poly(vinyl alcohol) (PVA) + H 2O and PVA + PEG + H 2O in the concentration range of 0.5–5 wt.% at different temperatures of 298.15, 308.15, 318.15 K, have been measured. The molecular weight of PVA and PEG were 67,000 and 3000, respectively. The mass ratio of PVA to PEG was selected as 75:25, 50:50, 25:75 in the ternary solutions. From density data the apparent specific volumes were obtained and correlated using a semi empirical equation. From viscosity data, the relative, specific and intrinsic viscosities for binary and ternary mixtures were obtained. The compatibility or incompatibility of two different polymer chains was concluded by using densimetric and viscometric method at different temperatures.

Study on fiber openness using image processing technique

It has long been recognized that the quality of yarn depends on the performance of the processes during spinning. This work relates to evaluating the opening action of blow room and aims to develop the openness tester for measuring the openness of fibrous assembly based on the image processing technique. A sequence of shapes taken using black background for high image clarity as radial projections at a fixed angular interval was recorded for image processing for each object. Each shape was treated as a slice of the cross-section of the object taken at a specific angular position. Fast 8-point connectivity, clockwise contour-tracing algorithm was implemented in MATLAB to extract the boundary points on the shape of each slice. With known angular position and the coordinates of boundary points, a three-dimensional wire-frame model has been created for three-dimensional visualization and volumetric measurements. The relation between the apparent volume and the weight of fibrous assembly has been studied. Finally, an apparent specific volume of fibrous assembly has been calculated as a measure of openness of fibrous assembly. The conventional test method (i.e. beaker method) and its openness index were compared with the apparent specific volume of fibrous assembly. Both the methods have shown a similar trend of openness of material. This work has further been extended in comparison of different types of modern blow room lines.