viscosity

A review of the literature on the phenomenon of aging (a significant drop in viscosity over time) of acidic chitosan solutions is given. A study was made on acetic acid (2%) solutions of chitosan of two viscosity-average molecular weights (200 and 46 kDa) by ion probing (addition of a KI solution). It has been indirectly confirmed that the motion of the probing ions in an electric field disturbs part (about a quarter) of the average macromolecule rather than the whole one.

Hydrodynamic, optical, colloid-flocculating, film-forming and structural morphological properties of diluted chitosan solutions (50–640 kDa) in acetate buffer (0.33 М СН3СООН + 0.2 М СН3СOONa), both initial ones and stored for ~1,850 days, were studied. It has been established that the decrease in the intrinsic viscosity of solutions over time is manifested for the reprecipitated and high-molecular-weight samples of chitosan to a greater degree.

Kinetic regularities of the alkaline hydrolysis of copolymers of methyl acrylate, butyl acrylate, vinyl acetate and acrylic acid of several chemical compositions under various conditions were studied by IR spectrometry. The initial rate of alkaline hydrolysis and the limiting conversion degree were shown to increase with increasing concentrations of the components of the reaction mass and temperature.

The isothermal behavior of systems SDS – H2 O and SDS – H2 O – electrolytes has been investigated in the range 0–100 °C. The effect of the addition of sodium chloride, salicylic acid and sodium salicylate on the nature of phase transitions was shown. The viscosity of aqueous solutions of SDS (0–30 wt. %) was studied. The view about the nature of possible self-assembled structures in the systems was expressed.