A. M. Bochek

Effect of Hydrogen Bonding on Cellulose Solubility in Aqueous and Nonaqueous Solvents

Interrelation between the hydrogen bonding energy in cellulose, its solubility in aqueous and nonaqueous solvents is examined. Factors controlling the solubility and selection criteria for nonaqueous solvents for cellulose are analyzed.

Determination of the Esterification Degree of Polygalacturonic Acid

The number of free and esterified carboxy groups of polygalacturonic acid was determined by conductometric titration.

Specific features of cellulose and chitin dissolution in ionic liquids of varied structure and the structural organization of regenerated polysaccharides

Solubility of cellulose, chitin, and chitosan in seven ionic liquids of varied structure was studied. It was found that pressure, temperature, and amount of an aprotic diluent (dimethyl sulfoxide) affect the dissolution of cellulose and chitin in an ionic liquid. The variation of the degree of polymerization of cellulose and chitin in ionic liquid solutions was studied. IR Fourier spectroscopy and X-ray diffraction analysis were used to examine the structural organization of hydrated cellulose and chitin films obtained.

Interaction of Water with Cellulose and Cellulose Acetates as Influenced by the Hydrogen Bond System and Hydrophilic-Hydrophobic Balance of the Macromolecules

Interaction of cellulose and cellulose acetates of different degrees of substitution with water, ethanol, and chloroform was studied by the sorption technique. The factors determining the solubility in water of cellulose acetates with degrees of substitution varied in a narrow range were studied.

Formation of Physical Thermally Reversible Gels in Solutions of Methyl Cellulose in Water and Dimethylacetamide and Properties of Films Thereof

Gelation conditions in solutions of methyl cellulose in water and dimethylacetamide were studied. The gelation mechanisms were studied by X-ray diffraction and photocolorimetry, and their differences in the two systems were revealed. The physicomechanical properties of methyl cellulose films prepared from solutions with preliminary gelation were determined.

Specific features of chitosan-montmorillonite interaction in an aqueous acid solution and properties of related composite films

The rheological properties of chitosan solutions in a 2% aqueous solution of acetic acid with added montmorillonite nanoparticles and the mechanical properties and structural organization of chitosan-based composite films are studied. The interaction between the polymer functional groups and surface charges of nanoplatelets is confirmed by conductometric and potentiometric measurements. With the use of a X-ray diffraction analysis, it is shown that the nanoparticles in films are in the exfoliated and intercalated states. The incorporation of up to 10 wt % modified montmorillonite nanoparticles into the chitosan matrix results in a successive increase in rigidity and a decrease in the elongation at break.

Fabrication of microcrystalline and powdered cellulose from short flax fiber and flax straw

Conditions of manufacture of microcrystalline cellulose from variously treated short flax fibers and of powdered cellulose from flax straw were examined. The effect of fats, waxes, and pectins contained in the fibers on the kinetics of hydrolysis of the polysaccharide was studied.

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.

Compatibility of carboxymethyl cellulose ionized to various degrees with poly-N-vinylformamide in composite films

Composite films were obtained from aqueous solutions of blends of carboxymethyl cellulose ionized to various degrees and poly-N-vinylformamide. The composition ranges in which the polymers are compatible were determined by solvent vapor sorption and by dynamic mechanical analysis. The heat resistance of the films and the interaction of the polymers in the solid state were examined by DSC, TGA, and Fourier IR spectroscopy.

Molecular mobility of chitosan and its interaction with montmorillonite in composite films: Dielectric spectroscopy and FTIR studies

The interaction of chitosan in the basic form with montmorillonite at different concentrations in composite films is studied with the use of dielectric spectroscopy and FTIR measurements. It is shown that the interaction of amino groups and primary hydroxyl groups of chitosan with local charges on the surfaces of montmorillonite nanoparticles is responsible for a change in the system of intramolecular and intermolecular hydrogen bonds that is typical for polysaccharides. The glass-transition temperature of chitosan in the composite systems is measured.