EFFECT OF CONTAINER SIZE ON GELATION TIME - EXPERIMENTS AND SIMULATIONS

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