| Research and development on bone renovating material have attracted the global and have been a very active field in the research of biomaterial. As the need of bone renovating material is increasing for the reason of human's injury, inflammation, carcinoma and congenital abnormality, the research of it has gone deeper and deeper, the ways of development have been more varied.Recently, bioceramics, especially hydroxyapatite(HA) has gradually become an active field. Because bioceramics is avirulence, innocuousness, good bioactivity and biocompatibility, high hardness and Young's modulus closed to body bone, it can be made for bone renovating material. So it can offset the shortage of metal material and organic material. With the old age of population and the need of renovation of abrasion, pathological changes, wound and abnormality of body parts, the study, development and application of bone renovating material in clinic have very wide foreground. However, the bioceramics also has some problems such as weak mechanics strength, brittleness, difficulty of processing and shaping, easy to run off or weak up and lack of bone induction. So in recent years, many kinds of nano-HA composite have been studied to solve these problems.The study of composites based on carbon nanotubes(CNTs) have become the hotspot of new material in recent years. Besides very great strength, tenacity, density and high Young's modulus, CNTs also has other properties such as excellent electricity, magnetism and absorbing wave. It is considered as a kind of strong one-dimension intensified material. Also CNTs has the property of biology because it can kill cancer cells effectively and make no damages to the normal tissue nearby. The research showed the CNTs can advance bone cell's growth and its structure is similar to the HA crystal in natural bone under nanoscale. Recently, many materials have been found can cover or be covered by CNTs. When CNTs and nano-HA are compounded, its mechanics property can be advanced as keeping its biocompatibility. So it can be prepared into an active biomaterial.Poly lactide(PLA) is a kind of degradable and absorbable material with good biocompatibility and mechanical properties. When compounding with other materials, It has good mechanical properties, can strengthen combinative power among bones and has extensive applications in medicine. The mechanical properties of PLA are closely related to its chain structure. Physical aging will occur for PAL being as implanting material of body before use and after implanting, and its physical properties will be affected.Recently, the research on multi-wall carbon nanotubes(MWNTs) when being used in composites has mostly been limited in mechanical mix between them or just simple surface disposal. So it is hard to form stable conjugation with matrix. This leads its own advantage can not be exerted. So a series of surface disposal on MWNTs are made. MWNTs-COON is prepared by using the methods of gas-phase oxidization and liquid-phase oxidization. And its surface is coated with Nano-HA to improve its composite properties combining with the preparation technology of bone material. The preparation of modified-MWNTs/nano-HA was main content, the preparation method of porous modified-MWNTs/ Nano-HA/ PLA was studied and its properties of mechanics,biology and degradation were debated in this paper.A series of experiments had been designed:1. Nano-HA with different sizes were prepared by using the method of chemical precipitation under different technology conditions, respectively. The effect of many conditions such as dispersion method, reaction time and cleaning solvent on the particle diameter were studied through particle size measurement and FT-IR characterization, and the optimal experiment condition was decided.2. MWNTs-COOH was prepared by methods of gas-phase oxidization and liquid-phase oxidization. MWNTs-COO/nano-HA composite were in situ synthesized by coating MWNTs-COOH with nano-HA with the assistance of ultrasonic. And MWNTs-COO/nano-HA/PLA which could be used as bone repair materials were produced with this composite and PLA by melt blending method. Many methods such as FT-IR, XRD, TEM, and Tensile Testing showed that MWNTs-COOH was coated by nano-HA completely, and MWNTs-COO/nano-HA particles were nanograde. The effect of the content of MWNTs-COO /nano-HA in PLA on the mechanical properties of the composites was studied and the optimal content of MWNTs-COO /nano-HA in PLA was decided in the experiment.3. Different perforating methods were compared on the basis of the request of bone renovating material to biologic properties such as pore diameter and porosity. Porous bone renovating materials were prepared by the method of solvent casting—chemical foam formation and using ammonium bicarbonate as a porosifer. The appearance and the permeance of this prepared material are all excelled to other methods. And the dosage of porosifer was decided. At the same time, the degradation experiment outside body, lost weight rate, pH value of degradation solution and transmitted light rate of this material were made. The degradation trend of this bone renovating material was attained and the degradation mechanism was debated. |
PDF Full Text Request