M. V. Radugin

Interaction of water-DMSO mixtures with cellulose

The character of the interaction of cellulose with water-dimethyl sulfoxide mixtures is investigated. It is shown that, in the concentration range 0 < xD < 0.28, cellulose predominantly sorbs water; in this case, in the presence of small amounts of DMSO (xD ∼ 0.1), the sorption is higher than that for pure water. It is established that the formation of hydrogen bonds between hydroxyl groups of cellulose and oxygen atoms in DMSO molecules is most probable at xD > 0.6, where large clusters dominate over hydrophobic dimers.

Interrelation between the crystallinity of polysaccharides and water absorption

The maximum sorption of water and its vapors is calculated using experimental data from calorimetric and effusion studies of flax, wood, and cotton cellulose. X-day diffraction is used to determine the crystallinity of cellulose samples. The equations relating crystallinity (X) with maximum sorption and the enthalpy of interaction between cellulose and water are presented. Experimental results and the literature data on water sorption by chitin, chitosan and other polysaccharides show that our equations for calculating crystallinity are correct.

Enthalpies of interaction of water with microcrystalline cellulose having different degrees of dispersion

Changes in enthalpy during the interaction of different kinds of microcrystalline cellulose and water were determined. The integral and differential enthalpies of polysaccharide interactions with water were calculated. The amount of water retained by the cellulose was determined. The effect of mechanical processing on these characteristics was demonstrated.

Synthesis of water-soluble copolymers containing porphyrin fragments in the side chain

The methods for the synthesis of water-soluble copolymers having porphyrin units in the side chain are described. Molecular-mass characteristics of the copolymers and mole content of porphyrin in copolymers are determined.

Dependence of the enthalpy of polyvinylpyrrolidone dissolution on the composition of water-ethanol solvent at 298 K

Changes in enthalpy upon the dissolution of polyvinylpyrrolidone in a water-ethanol solvent were determined. The effect of temperature, the molecular mass of the polymer, and the ethanol content in the mixed solvent on these characteristics was demonstrated.

Temperature Dependence of Physicochemical Characteristics of Redox Processes Involving Thioindigo Red C

Cyclic volammetry in water at 298-323 K was used to determine the thermodynamic and kinetic parameters of redox processes involving thioindigo red C. The resulting values were shown to depend on temperature and entropy.

Method of obtaining the thermodynamic characteristics of redox behaviour of vat dyes in aqueous media

Abstract Cyclic voltammetry is suggested as a method for determining the thermodynamic characteristics of redox behaviour of vat dyes. In contrast to the existing methods of studying the redox properties of this class of dyes (spectrophotometric and potentiometric titration), the application of which is limited due to insolubility of the vat dyes, the suggested technique allows the investigation to be performed in an aqueous medium for the entire pH interval.

Enthalpies of interaction between cellobiose and the derivatives of cellulose in aqueous solutions

The enthalpy of interaction between cellobiose and sodium carboxymethyl cellulose, methyl cellulose, and 2-hydroxyethyl cellulose in water is determined. The exothermal nature of the interaction between cellulose and cellulose ethers is established. The strongest intermolecular interaction is found between cellobiose and 2-hydroxyethyl cellulose. The results are discussed in the context of the polysaccharide molecular structure.

Application of calorimetry to the studies on the processes of dyeing of fabric

Abstract The possibility of the use of direct thermochemical measurements for the determination of the enthalpic characteristics of the most important processes taking place during the dyeing of textile materials by reactive dyes is shown. It is established that the exothermicity of dyeing decreases with the rise in the degree of association of the dye and the degree of filling of the fibre surface by the dye molecules, and with the decrease in the degree of swelling of cellulose. This testifies to the importance of the entropic factor for the dyeing process of cellulose materials by reactive dyes.