X-Ray Diffraction and DSC Measurements of Frozen Sodium-Montmorillonite Amount of the Unfrozen Water and Its Location

Abstract

The frozen pastes of uncalcined and calcined sodium-montmorillonites having various water contents were prepared in order to determine the interlayer spacing (d(001)) using an xpray small angle scattering. The samples calcined at the temperatures below 600°C-still swelled due to water vapor, while those calcined above 700°C did not. From the differential scanning calorimetry (DSC) measurements of these samples, the heat of fusion was determined. It was found that the unfrozen water existed even in the frozen paste of sodiummontmorillonite calcined below 600°C and that the amount was O.45 g-Water/g-Clay. Because the unfrozen water did not exist in the frozen paste of sodium-montmorillonite calcined above 700°C, it is suggested that the unfrozen water exists only in the interlayer space but not in the interparticle space. On the basis of the amount of the unfrozen water and the volume of the interlayer space, the density of the unfrozen water was estimated to be 2.0 g/cm³.