Studies On Preparation And Properties Of Modified Hydroxyapatite/High Density Polyethylene Artificial Bone Composites

The hydroxyapatite (HA) was prepared by the method of neutralization deposit, and its surface modification was carried out using monophosphatase (PL) coupling agent through fusing and mixing. The modified HA / high density polyethylene (HDPE) artificial bone composites were prepared. The structure and physical, chemical and biological properties of the composites have been studied in the present master thesis.The influences of the diameter of HA, the calcining temperature of HA, the addition of coupling agent and mixing conditions on surface modification of HA have been studied. The results showed that the monophosphatase (PL) was a kind of excellent surface modification coupling agent with good reactivity, it could react with the hydroxyl (-OH) in HA surface and form a stable chemical bond. The optimum process conditions in surface modification were obtained: the HA calcining temperature:1000℃, the addition of PL coupling agent: 0.7wt%.The preparation and properties of modifiied HA / HDPE composites have been investigated also in this study. The results showed that the modified composites possessed good rheological properties, machinability, homogeneity and thermal stability. PL coupling agent could enhance the interface combination between HA and HDPE, and improve the dispersibility and fill content of HA in the HDPE basis.With the increase in HA content, the flexural strength and flexure modulus of composites had been greatly increased and the tensile strength of composites had only a little change. Through the "bridge -connection" action of PL coupling agent, it could be realized to increase the strength of composites by the dispersion of HA, and to improve the tougheness of composites through the tenacity addition action of HDPE. The artificial bone composites with good mechanical properties might be prepared through controlling the content of HA or HDPE in the composites.The biological properties of HA/HDPE composites were studied through the vitro dissolution test of composites in the simulated body fluid (SBF) and the blood compatibility test of composites. The results showed that the composites were a kind of non-degradable biomaterials. The evaluations with kinetic clotting times and hemolysis showed that the composites possessed better blood compatibility than polyethylene.