Small-angle neutron scattering and rheological characterization of aluminosilicate hydrogels

Structure and formation of aluminosilicate hydrogels were investigated as a function of chemical composition. Oscillatory rheometry was used to measure the dynamic moduli, G' and G", of the gels during setting. The formation of aluminosilicate hydrogels was monitored over time as a function of the storage modulus for gels of low solids volumes, phi < 0.030. Overall gel strength correlated well to the fractal dimension, D, observed by neutron scattering. Scattering data were interpreted using the power law, and the Guinier relationship was used to determine the size of the constructing colloidal/gel particles. Aluminosilicate hydrogels were observed to consist of large fractal aggregates of indeterminable size constructed from smaller subunits of similar to45 Angstrom in dimension. Structure and formation of the gels were highly dependent on [Al2O3] and [Na2O] content.