EFFECT OF CONTAINER SIZE ON GELATION TIME - EXPERIMENTS AND SIMULATIONS

The gelation time t(g) of silica gels has been determined experimentally in containers of different sizes. It is found that t(g) is almost independent of the container size for gels prepared without a catalyst while it increases with the container size for gels prepared under basic catalysis. These results are explained by numerical simulations based on the recently developed fluctuating bond aggregation model which considers a possible cluster flexibility during the sol-gel process. Gelation under basic catalysis or without catalysis corresponds to small and large flexibility, respectively, in agreement with what is known on the corresponding aerogel structures.