Influence of the ice front velocity and of the composition of suspensions on thermal properties of bentonite materials prepared using freeze–casting process

Abstract : The influence of (i) the ice front velocity in the freeze–casting process as well as the addition of two binders, (ii) the inorganic synthetic mineral laponite and (iii) the natural organic oligomer chitosan, on the microstructure and on thermal conductivity of bentonite materials prepared using the freeze–casting process were investigated by scanning electron and interferometric microscopies and the laser flash method. Prior to measurements, materials physico-chemical characteristics were determined using specific surface area, grain size and density measurements. Results show that the width of the strongly oriented pores obtained with the freeze–casting process is modified by the presence of binders, and that in turn, the thermal conductivity and anisotropy are also significantly modified.