Sol-gel transition in SnO2 colloidal suspensions : viscoelastic properties

Paper describes particle aggregation process during gelation of SnO2 hydrosols. The effects of the concentration of SnO2 colloidal particles on the kinetics of gelation of hydrosols containing PVA was analyzed. The complex viscosity and the storage and loss moduli have been measured during the sol-gel transition and the results correlated to mass fractal growth, nearly linear growth models, and scalar percolation theory. The analysis of the experiemental results shows that a linear aggregation occurs in the initial step of the gelation followed by a fractal growth to form a 3-D network. Near the gel point, this physical gel exhibits the typical scaling expected from an electrical percolation analogy. 12 refs.