NON-NEWTONIAN PROPERTIES OF HYALURONIC-ACID AQUEOUS-SOLUTION

The systems comprising hyaluronic acid (HA) aqueous solution and acety lsalicylic acid salt in the HA solution were studied. It was found tha t both systems display pseudoplastic behaviour. The viscosity (eta) de pendence of the shear rate (gamma) of thes systems was fitted using no n-linear regression, with the best accuracy achieved by the empirical formula eta proportional to gamma(-3/4). The radius of equivalent sphe res (r(eq)) representing non-interacting, compressed macromolecular ch ains was calculated from the regression constant, and was plotted as a function of salt concentration. The compressing effect of the HA chai ns is caused by the presence of acetylsalicylic acid salt in the aqueo us solution; the polymer chains change their shape into contracted str uctures as a result of suppressing the repulsion in the polyelectrolyt e chain by adding salt counterions. At low salt concentrations, the lo west values of r(eq) were found if the acetylsalicylic acid salt with the highest ionic strength (magnesium salt) in the HA solution was pre sent.