Sintering aerogels

Studies of the densification kinetics and structural evolution of non-cryst alline aerogels during sintering are examined in light of theory. In most r espects, the theory of viscous sintering is capable of quantitatively accou nting for the experimentally observed behavior, as long as the initial pore size distribution is known. Unfortunately, it is difficult to obtain adequ ate structural information; in particular, measurements using nitrogen deso rption and thermoporometry often erroneously indicate the presence of macro porosity. Some authors have claimed that large pores contract more quickly than small pores during sintering; under certain circumstances this is pred icted by the theory.