Hydrolysis in the Aluminum sec‐Butoxide—Water—Isopropyl Alcohol System: I, Rheology and Gel Structures

Solutions representing a wide range of compositions in the aluminum sec-butoxide-water-isopropyl alcohol system were prepared. Viscosity measurements were made on solutions hydrolyzed at 20°C, Large differences were observed between low-water solutions and high-water solutions, both in the time evolution of the viscosity and in the effect of isopropyl alcohol content on the viscosity. Higher values of viscosity were attributed to polycondensation of partially hydrolyzed species, while lower values of viscosity were attributed to hydrolyzed clusters. The reduced viscosity was independent of oxide content for low-water solutions, but decreased with increasing oxide content for high-water solutions.