| Nano-hydroxyapatite was the main inorganic mineral component in human bone,which is of great potential for application as artifical hard tissues substitute materials in orthopedic for its favorable biocompatibility and osteoconductivity.However,the difficult of forming and low strength limited the usage of nHA in weight-bearing bone repairing materials.Polyetheretherketone is a kind of semicrystalline thermoplastic polymer with excellent stability and mechanical properties,which is also harmless to humans.By incorporating nano-hydroxyapatite(nHA) into PEEK matrix,the functional composite materials would integrate their respective advantages presenting the high strength and high biocompatibility.Selective Laser Sinstering, as a category of 3D printing,has its own unique benifits in forming repairing bone with complex curved surface and pore structure.Therefore developing bone repairing composite materials which meet the requirement of SLS has a definite significance in science and application.The thermal oxidative aging properties of PEEK and the effects of different types of antioxidants on thermal stability and mechanical properties were investigated in this paper. The thermal oxidative aging mechanism of PEEK were deduced through infrared spectrum,the results showed that antioxidant 2921 T and TiO2 could drop yellowing index under 330℃,the tensile strength and impact strength of the materials after thermal oxidative aging presented no substantial increase or decrease. PEEK were pretreated with water,absolute ethanol,sulfolane,and 50wt% ethanol water solvent under high-temperature and high-pressure,the result showed that absolute ethanol was the optimal solvent(the system pressure is 5.8MPa)and it has significant effect on apparent density and particles morphologies of the powder.the apparent density increaesd and regular shape powders can be obtained under the treatment of absolute ethanol,Meanwhile there appeared a dozen micrometer of PEEK powder,This morphology of PEEK is of benefit to gain flowability,increase the densification of the product,which is advantageous to SLS.Nanometer-size hydroxyapatite(HA) crystals were prepared by a chemical precipitation method in the pH 11-13 using Ca(NO3)2 and(NH4)2HPO4 as precursors,the product were characterized with X-ray diffraction,infrared spectroscopy and scanning electron microscope respectively.The result showed the average size of spherical nHA was 79 nm with high crystallinity.The homemade nano-powder of HA were modified by stearic acid.The composites with 0-20wt% HA were prepared by compression molding,the heat tolerance and mechanical properties of the composites were studied in this paper.The result showed that the addition of 2.5wt%HA has no effect on PEEK crystallization behavior,but improved the heat-durability of the composites,the hardness and flexual modulus increased with the increase amount of HA.when HA content was below 2.5wt%,the tensile strength,the flexual strength,the vicat softening point and the impact strength increased obviously with the increase of the content of the HA,when HA content was above 2.5wt%,the four parameters decreased with the the increased content of the HA,when HA content was lower than 5wt%,the four parameters were superior to that of PEEK.After exceeding 5wt% HA,the four parameters fell sharply.the composites showed the optimal dispersion with 2.5wt% HA,there existed interface adhesion between HA and PEEK.The HA/PEEK composites were modified in blending polyimide(PI),the results showed that the addition of PI improved the crystallization of PEEK,and had greatly improved the heat resistance of the composites,with the increase in PI content,the the tensile strength,the flexual strength,the vicat softening point improved,when the proportions of HA/PI/PEEK were 3/10/87,the above three parameters attained the maximum.Then it decreased when the HA was above 3wt%,the addition of PI leaded to the decrease of impact strength,and PI content had little influence on the bending modulus. |
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