Abstract: The thickening and ion resisting effect of five kinds of polyacrylic acid type common thickeners were tested.Viscosity of their aqueous solutions at different mass fraction were measured,and the variations of viscosity with pH value were examined.Results show that co-polymer Carbomer 940 displays the best thickening performance,but its viscosity varies with pH value 2-11.The thickening effect of co-polymers that contain metal ions AVS,EMT-10 and HMB displays a general state,and their viscosity is stable within pH value 5-11.The thickening effect of bulk-polymer Zen is the lowest,while its viscosity is stable within pH value 2-8.NaCl and MgCl₂ were added separately to aqueous solution of the five kinds of thickener to examine the influence of common ions in cosmetics on their viscosity.Addition of the salts declines the stability of the aqueous solution of all the five kinds of thickener.However,bulk-polymer Zen displays the best ion resistance.Blends composed of Carbomer 940 and Zen were tested,and their thickening and ion resistance were measured.Result shows that there is synergic effect for thickening performance of the Carbomer 940-Zen system.Both thickening effect and ion resistance can be improved by blending of Carbomer 940 and Zen.

Key words: additive of cosmetics, polyacrylic acid, thickener, viscosity, ion resistance