Effect of the temperature on the structural and textural properties of a compressed K-vermiculite

K-vermiculite pellets were obtained by compression (80 MPa, 25 °C or 200 °C) of submicrometer size vermiculite particles. The evolution of the structural and textural properties of the compressed materials was studied as a function of the annealing temperature in the 400-1000 °C range. Small Angle Neutron Scattering patterns of the pressed samples suggest a preferential orientation of the vermiculite particles for which the basal planes were arranged perpendicular to the compaction axis. Thermogravimetric analyses, Scanning Electron Micrographs, density and porosity measurements show that the most significant changes occurred for annealing temperatures higher than 800 °C. When heated above 800 °C, the pressed vermiculite samples undergo a simultaneous increase in density and decrease in porosity concomitant to a structural evolution, leading to a more three dimensional-based structure.