Rheological measurements were carried out on dilute aqueous solutions of high (HMW-HA, 1150 kDa) and low molecular eight hyaluronic acids (LMW-HA, 8 kDa) along with their mixtures to determine the relationship between the viscosity and concentration of the samples, Molecular weight and polydispersity of low molecular HA have been determined by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). HA diluted solutions ere found to be weakly structured liquids with a slight viscosity anomaly. Critical aloes of concentration ere determined at different ratios of HMW-HA and LMW-HA leading to a sharp increase in the viscosity of solutions. Rheological studies have proved the pseudoplastic nature of the viscous flow of HMW-HA solutions. The possibility of using the Ostwald-de Wale equation for the mathematical description of a viscous flow was established. The results of the 'theological analysis might be applied for the rational development of cosmetic formulations containing hyaluronic acid of various molecular weights.
