Evolution of the porous volume during the aerogel-glass transformation

The evolution of the texture of a silica aerogel during sintering is studied by thermoporometry. During the first stages of the densification the macroporous volume drops strongly while the mesoporous volume seems to be constant. This behavior is in contradiction with sintering models which predict that the sintering rate is faster for bodies with smaller particles or pores. In fact the analysis of the micropore size distribution shows that the sintering of the mesopores is responsible for macropore decrease.