STABILITY AND RHEOLOGICAL PROPERTIES OF SUSPENSIONS

An injectable phosphocalcic ceramic suspension considered as a ready-to-use injectable bone substitute was studied. The sedimentation kinetics of the phosphocalcic particles showed the influence of the particle size and the concentration of the suspending fluid on the sedimentation rate and on the compactness of the sediment before and after sterilization. The rheological and injectability properties of this phosphocalcic suspension were then studied. We showed that the suspensions have a higher viscosity compared to the HPMC solution and that the rheological properties depend on the composition of the suspension. The injection simulation was performed using a syringe with a needle. A theoretical approach based on the capillary flow of a non-Newtonian fluid was used to predict the injection pressure from the rheological results and the extrusion operating conditions. The theoretical estimation of the extrusion pressure confirmed the wall slip. The influence of slip led to a constant proportionality factor between theory and experiment.