| In present research, a new type of high hydroxyapatite content nano-hydroxyapatite(n-HA) paricel reinforced polyamide 66 (PA66) (n-HA/PA66)composite was developed as the artificial ilium for resolving the problems occurred in titanium mesh and ilium-grafting in cervical spine surgery, by considering the compositional characters of natural bone. The rod-like nano-hydroxyapatite particles were prepared via hydrothermal route. With the hydrothermally made n-HA, the n-HA/PA66 biocomposite was produced by co-precipitation and heat-pressing. The phase and group compositions of the composite were characterized by IR and XRD. The reinforcement dispersion was characterized by TEM. The measurements of biomechanical properties were carried out with normal cervical specimens, bone-grafting specimens with n-HA/PA66 biocomposite, and the ilium-grafting specimens fixed by steel plate and bolt. The in-vitro biocompatibility was tested by keeping the specimen in simulated body fluid (SBF) at body temperature for 3,14,21 and 28 days.Under the pressure of 10MPa, the 40wt%, 50wt% and 60wt% n-HA/PA66 were prepared at different processing tempertures. XRD results revealed that the main diffraction curves of nano-hydroxyapatite and polyamide66 remained in the composites, but n-HA made the peak ofβPA66 wider and weaker. IR spectrum showed that the hydrogen-bonding formed between nano-hydroxyapatite and PA66. TEM indicated that the size of n-HA without obvious increace and deipersed in the composite without obvious conglomeration. The bending test suggests that there is an optimal processing temperture for the composites with the same n-HA content, at which the produced specimen possesses the beat bending strength.The bending strength of 60wt% n-HA/PA66 is 80.84MPa, By following ASTM D0256-05, ASTM D0638-03 and ASTM D0695-02A standards, impact toughness, tensile strength and compressive strength of 60wt% n-HA/PA66 were determined as 11.8KJ, 71MPa and 95MPa, respectively, higher than those of 40wt% and 50wt% n-HA/PA66 compistes. The mechanical properties of 60wt% n-HA/PA66 composite are similar to natural compact bone。After keeping 60wt% n-HA/PA66 composite in simulated body fluid (SBF) for 3d, the SEM images showed that a little precipitation of particles apatite appeared on the surface of the composite. A thick apatite layer was formed after 14 day's SPF incubation. With the increasing incubation durations, the thicknesses of precipitated apatite layers were apparently increased, which indicated a easy bone fusion around n-HA/PA66 composite in the body. Experiments in the cervical vertebra sheep implanting also showed that composite was a kind of non toxic, good mechanical performances, biological activitive material.60wt% n-HA/PA66 composite implanted sheeps for three months, six months, the compressive strength, elastic modulus testing results showed that as compared with non-implantation they declined certainly, but as time passed the decline has become slow. The biomechanics results indicated that the bone-grafting cases with 60wt% n-HA/PA66 biocomposite are of better performances in load-strain, load-displacement, stree intensity and axial rigidity in comparison with ilium-grafting ones, only a little bit lower than the normal cervical, it was a goog kind of materials to replace normal cervical.
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