Evaluation of nano particle slurries by osmotic pressure measurement and its application to fabrication process of nano composite materials

Abstract

The dispersion and aggregation state of nano particle slurries was evaluated by our developed osmotic pressure measurement. The ionic concentration and pH of slurries were changed in order to control their particle dispersion and aggregation state. In addition, these slurries and an acrylic resin were fabricated into nano composite materials. The microstructure and transparency of the fabricated nano composites were evaluated, and the relationship between the slurry evaluation results and composite material properties was discussed. For nano silica slurries with increasing amount of salt (NaCl), the osmotic pressure of the slurry became lower. Also, for nano zirconia slurries with different pH values, the osmotic pressure increased as the magnitude of zeta potential of the particles increased. This osmotic pressure change due to the ionic concentration or zeta potential reflected the dispersion and aggregation state of the nano particles, as evaluated by centrifugal sedimentation test and median diameter measured by dynamic light scattering. Furthermore, the microstructure of fabricated nano composite materials was greatly affected by the particle dispersion state of nano particle slurries, indicating that the osmotic pressure measurement for nano particle slurries could be useful for evaluating the particle dispersion state and predict the microstructure of fabricated nano composite materials.