Physical chemical and thermoanalytical characterization of cements based on synthetic hydroxyapatite

Abstract

The synthesis and characterization of cements based on hydroxyapatite are reported. The cements were prepared by mixing a solid
phase formed by hydroxyapatite (HAP), gypsum, sodium alginate (NaAlg) and N,N-poly-vinil-pirrolidone with a liquid phase containing potassium sulfate and potassium phosphate. The samples so prepared as well as the major components (hydroxyapatite and gypsum) were characterized by xray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric and differential thermal analysis. The cements so prepared, as well as the major components (hydroxyapatite and gypsum) were characterized by different techniques. The results of FTIR and XRD confirm the high purity and cristallinity of the HAP synthesized and used as raw material for the synthesis of the cements. The relative intensities in the FTIR spectra of the bands assigned to PO₄^3- groups and water change with the composition of the cement. FTIR of cements also indicate a reductionin the cristallinity degree of the HAP during the cement formation, confirmed by XRD results, and the appear of new bands assigned to the vibration mode of carboxylate groups from the polymers used. The thermal behaviour of the cements is also affected by the composition of the cements.