Temperature Dependences of HCl Activity Coefficients in Aqueous Solutions

Temperature coefficients of activity of the ionic fraction of HCl in water, calculated from tensimetric and calorimetric data, are compared. A correlation dependence is suggested for recalculating the activity coefficients of hydrochloric acid from 298 K to other temperatures.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 211–213.Original Russian Text Copyright © 2005 by Poltoratskii, Osovskaya, Chumanov.     

Hydrophilic Characteristics of Cellulose Treated with Saturated Water Vapor

The reaction of water with cellulose treated with saturated water vapor at various temperatures for various times was studied. Trends in variation of its sorption and hydrophilic characteristics were examined.     

Solution behavior of methyl cellulose mixtures with poly(<Emphasis Type="Italic">N</Emphasis>-vinylformamide) in water and dimethyl sulfoxide

The rheological properties of diluted and moderately concentrated solutions of methyl cellulose mixtures with poly(N-vinylformamide) in water and dimethyl sulfoxide are investigated. Negative deviations of the viscosities of these solutions from the additive values are observed and explained by different mechanisms of solvation of macromolecules with water and dimethyl sulfoxide. Incompatibility of the polymers in a common solvent is discovered. This circumstance leads to the formation of a new system of hydrogen bonds and rearrangement of the structural organization of solutions.     

Mean Ionic Activity Coefficients and Dissociation Constant of HCl in the System HCl-H2SO4-H2O at 298 K

The mean ionic activity coefficients of HCl (_1±) in the system HCl-H₂SO₄-H₂O at 298 K were calculated by the Mikulin and MacKay-Perring methods and were then used for calculating the mixed thermo- dynamic dissociation constant of HCl (K _m). The mean value of the constant proved to be equal to that found previously for aqueous solution of HCl, and deviations from the mean value are most likely due to the fact that, when calculating K _m, incompleteness of dissociation of both electrolytes was neglected. The _1± values calculated by the MacKay-Perring and Mikulin methods virtually coincide, within the determination and calculation errors, with the published data. This result confirms the suitability of the previously suggested procedure for determining the strictly thermodynamic mixed dissociation constants from the experimental data on the vapor pressure in combination with the mean ionic activity coefficients.     

Characteristics of composite films based on methyl cellulose and poly(N-vinylformamide) prepared from solutions in water and dimethyl sulfoxide

The stress-strain characteristics of composite films based on methyl cellulose and poly(vinylformamide) prepared from solutions of polymer blends in water and dimethyl sulfoxide are studied. The temperature of relaxation transitions in the mixed films and the concentration interval where the polymers are compatible are defined via the thermomechanical method and dynamic mechanical analysis. The effect of the nature of a solvent on the mechanism of crystallization of methyl cellulose, the stress—strain characteristics of the composite films, and the compatibility between the polymers is investigated.     

Effect of Aqueous Solutions of Biuret,Dimethyl Sulfoxide,and Acetamide on the Paper-Forming Properties of Cellulose

Chemical activation of cellulose material was studied as a means to improve the mechanical characteristics of experimental paper.