RHEOLOGICAL CHARACTERIZATION OF EASY-TO-DISPERSE (ETD) CARBOPOL HYDROGELS

Experimental determinations of apparent viscosity were used to investi gate the rheological behaviour of easy-to-disperse (ETD) Carbopol 2001 , 2020 and 2050 hydrogels, involving different polymer concentrations, degrees of neutralization, agitation times and shear rates. Mathemati cal expressions were obtained, based on the power law, to allow calcul ation of the viscosity of each system, for the different variables stu died. These equations proved valid within the 5.5-7.5 pH range, i.e., the pH interval of greatest interest in pharmaceutics and cosmetics. T he rheological behaviours of the three types of ETD hydrogels were inv estigated comparatively and with respect to Carbopol 940, i.e., one of the most widely utilized hydrogels.