Kinetic Study of Calcium Phosphate Cement Containing Chitosan in Its Liquid Phase

In this study, the kinetic mecha-nisms for the hydration process of calcium phosphate cement (CPC) containing chitosan in its liquid phase were investigated by X-ray diffraction quantitative analysis. The powder component consisted of an equimolar mixture of tetracalcium phosphate and dicalcium phosphate anhydrous. The liquid component consisted of chitosan (3 wt%), citric acid (5 wt%) and glucose (15 wt%) solution. The results show that the hardening process of CPC is initially controlled by the dissolution of reactants in a 2-h period and subsequently by diffusion through the product layer of hydroxyapatite (HA) around the grains. The compressive strength rises approximately linearly with the increase of the extent of conversion in a 2-h period, and a maximum compressive strength of 30.2±±0.8 MPa is obtained in 2 hours. Then the compressive strength drops a little with an increase in the extent of conversion. The final product of setting reaction is acicular HA crystal.