Low-temperature synthesized aluminosilicate glasses .2. Rheological transformations during low-temperature cure and high-temperature properties of a model compound

The reaction below 100 degrees C of a dehydroxylated clay (metakaolinite) suspended in an alkaline sodium silicate solution leads to an amorphous aluminosilicate, called in this work ''low-temperature inorganic polymer glass'' (LTIPG or IPG). Some rheological transformations during the isothermal hardening process are followed with dynamic mechanical analysis (DMA) and compared with differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC). It can be concluded that the change in storage modulus (DMA) during the formation of the inorganic network can be characterized quantitatively with the evolution of the heat capacity (MDSC), and that the reaction rate is not decreased by the vitrification process. During the first heating after polymerization up to 1000 degrees C, the material shrinks due to the evaporation of residual water from the reaction mixture as illustrated by thermogravimetric analysis (TGA) and thermomechanical analysis (TMA). The low-temperature synthesized inorganic polymer glass is thermomechanically stable up to a temperature of at least 650 degrees C. In that temperature zone, the glass transition can be detected with TMA and DMA.