Surface-Modification Of Hydroxylapatite Nanocrystals And The Mechanical Properties Of Polyetheretherketone Biocomposite Reinforced By Them

Nano-sized hydroxyapatite powder is hydrothermally synthesized with the use of CaCl₂ and H₃PO₄ as precursores under the conditions of 150℃, pH 9¹0 and 4 h. The prepared particles are characterized by virtue of Fourier Transform Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). They have a size 60¹00 nm in c axis and 20³0 nm in a axis, which is similar to that in human bone.The hydroxyapatite (HA) surface modification is carried out with different contents of silane coupling agent (SCA). The modified particles are characterized by virtue of Fourier Transform Infrared (FT-IR) spectroscopy, indicating that the nano-sized HA is coupled with the SCA (KH560) by a chemical bonding.The composites with 2-15vol.% nano-sized HA are fabricated by injection molding and characterized by mechanical testing. The Hv hardness and elastic modulus of the composite increases with increasing amount of HA particulate in the PEEK polymers. The tensile strength of the composite and the degree of crystallinity of PEEK both show a maximum values, occurring at an HA content of about 5.0vol.%. And at the same content, the inorganic fillers distribute uniformly within the composite through a physical bonding with the organic matrix.According to the above results, the mechanical propertities of HA/PEEK composite with an HA content of about 5.0vol.% are the best correspondingly. The SCA-HA/PEEK composites with 5.0vol.% nano-sized SCA-HA are fabricated by injection molding. The mechanical testing indicates that there is a peak value in the tensile strength of the composite at an SCA content of about 3wt.%, while the Hv hardness of composite increases continuously with increasing amount of SCA. Thus the mechanical and biological property of HA/PEEK composites should be optimized with 5.0vol.% nano-sized HA coupled with 3wt.% SCA.