Abstract: On the basis of rheological experimental results, we analyzed the rhe ological mechanism of the latex system. The viscosity mechanism of a common hard -sphere latex particle system is considered to be related to the hydrophilicit y of the polymer chain. The stronger the hydrophilicity is, the higher the viscosity is. In the acid medium, the viscosity mechanism of the system of latex particl es containing carboxyl is the same with that of the common hard sphere latex sys tem. But in the alkali medium, the system of latex containing carboxyl appears an a lkali-thickening phenomenon. So the alkali-thickening mechanism has been consi der ed to be attributed to the bridge-structure formed from the hydrogen bonds of the particles. This opinion is different from the early deduction “from th e swell to the solution of the latex particle”.

Key words: latex particle, viscosity, acrylic acid, alkali-thickening, hydrogen bond