Surface Organic Modification Of Hydroxypatite Particles Through UV Irradiation Polymerization Of Methacrylic Acid

In this paper, unsaterated double bond functional group was chemically inserted onto the surface of hydroxypatite(HPA) particles by esterification reaction with methacrylic acid, then the surfaces organic-modificated hydroxypatite particals were prepared through UV irradiation polymerization reation of methacrylic acid onto its surface.ESCA, FTIR test showed that the surfaces of HPA are successfully free-radical polymerized with methacrylic acid, so our research target has been realized.The effect of reaction temperature and time on the esterificating degree as well as that of irradiation time, esterificating degree and monomer-concentration on grafting degree of polymethacrylic acid on the surface of HPA were investigated. The results show that esterificating degree increases with reaction temperature and time, and reaches a maximum at 90℃, and then slowly increases after 6h. The grafting degree increases with monomer-concentration, esterificating degree and irradiation time, and reaches a maximum at irradiation time of 25min, and then decreases with irradiation time further delay.The microstructures of the surfaces organic-modificated HPA were observed by SEM. The results showed that compared with pure-HPA, the surface of organic-modificated HPA becomes more and more rough with irradiation time. The surface roughness degree reaches the maximum at 25min, and then decreased with irradiation time further delay. The partical size distribution of HPA was tested by laser particle size analyzer. The result shows that the average particle size of organic-modificated HPA increases with irradiation time, and reaches a maximum at irradiation time of 25min, and then decreases with irradiation time further delay, corresponding with the SEM analysis result.The mechanical properties were tested by Instron Material Tester. The tensile strength and Young's Modlule of PVA/organic-modificated HPA composites are obviously increased as compared with PVA/pure-HPA composites. The observation of tensile facture surface indicated that the interface of PVA /organic-modificated HPA composite system become obscure and blurring, and hydroxyapatite was dispersed homogeneously in PVA matrix as compared with PVA/pure-HPA composite system.