【作者】 赵萍；

【导师】 孙康宁；

【作者基本信息】 山东大学 ， 材料学， 2005， 博士

【摘要】 磷酸钙骨水泥(CPC)是一种新型的自固型生物活性骨水泥,具有良好的生物相容性、骨传导性、可降解性、可塑性,而且反应产生的热量少,是理想的骨替换及修复材料。但是在多年的研究与应用过程中,该类材料强度低、力学性能差的问题一直未能得到解决,力学性能仅介于松质骨与皮质骨之间,脆性大且承受载荷的能力差,限制了它的广泛应用,只能用于某些非承重骨及硬组织修复等。为了解决这一难题,人们从不同的角度入手进行了研究,其中包括:在固体粉料方面,采用不同的磷酸钙相互搭配、向粉料中加入外加剂等;在调和液方面,选用柠檬酸(钠)、苹果酸、磷酸钠盐等有机及无机调和液;另外,借鉴传统的增强方法,与晶须、有机高分子材料、短纤维等形成复合材料等。这些方法对磷酸钙生物骨水泥的力学性能都起到了不同程度的改善,其中以第三种增强方式获得的效果较好,力学强度得到一定程度的提高,但是整体效果仍不理想。 寻求一种新的复合思路及有效的增强物质,从而进一步提高磷酸钙骨水泥的力学性能,无疑对拓宽其应用领域,增强其与非生物骨水泥的竞争力具有重要的意义。 利用碳纤维强度高、韧性好等优异的力学性能以及良好的生物相容性,从仿生学的角度出发,仿照人体皮质骨的结构,即羟基磷灰石(HA)在纵向排列的胶原纤维束上结晶,以碳长纤维(CF)模拟胶原纤维束,得到纤维增强磷酸钙骨水泥复合材料,以期提高其力学性能。另外,近年发现的碳纳米管(CNTs)由于具备尺度小、强度高、弹性模量大、比表面积大、力学性能优异等特点,被认为是理想的纳米晶须增强增韧材料,甚至可能是纤维类强化相的终极形式,因此,将其作为一种新的增强相应用于骨水泥中,可望获得的复合材料在力学性能上同样得到提高。最后,在两种增强相单独发挥作用的基础上,将二者同时加入骨水泥,制备CF/CNTs协同增强的磷酸钙骨水泥复合材料,以达到力学性能进一步提高的目的。依据这一思路,设计制备了新型CF/CPC、CNTs/CPC、CF/CNTs/CPC复合材料,并对复合材料的制备工艺、微观结构、力学性能及增强作用进行了研究。本论文主要研究内容如下: 首先,对不同的骨水泥材料进行了制备及对比,包括普通α-磷酸三钙型、更多还原

【Abstract】 Calcium phosphate cement is a new type of self-setting cement. It is perfect material for bone substitution and repair, which shows excellent biocompatibility, osconductibility, biodegradability, plasticity and less reaction thermal. But in the studies before, the problems of low strength and mechanics were not solved. It is used to non-bearing bone and hard tissue repair because of its brittleness. To solve the problem many research were carried out. The first was solid powder, including the arrangement in-group for different calcium phosphate and the additive. Second several kinds of liquid, including citric acid, malic acid and phosphate natrium, were used. Another crystal whisker, organic material, chopped fiber were used to strengthen the material. We could see the higher strength, especially treated in the third method. But the whole effect was not good.It is of significance to search new thought and strengthening material in order to increase the mechanics for its application and competition.Following the structure of cortex bone, we replaced the collagen fiber by carbon continuous fiber and obtained the calcium phosphate strengthened by fibers, which was a class of biomaterial with better performance because of high strength and toughness of carbon fibers. Carbon nanotubes possess unique properties such as its small measure, high strength, the grate modulus of elasticity and specific surface area, and mechanics. It is believed to be an ideal toughening material and can obtain an composite with better mechanics. We use the two materials and prepare the calcium phosphate composite strengthened by CF/CNTs. We designed CF/CPC, CNTs/CPC, CF/CNTs/CPC composite, and investigated the preparation procedure, microcosmic structure, mechanics and strengthening effect. This study includes as follows:At first, we compared the different solid powder, a-tricalcium phosphate, tetracalcium phosphate, new type of α_H-tricalcium phosphate and β - tricalcium phosphate included, and test their microcosmic structures and mechanics, and then choose the α-tricalcium phosphate as the matrix. We optimized the preparation procedure of a-tricalcium phosphate by experiments of sintering parameters. Theproduction had high purity and stable performance. During the process of tetracalcium phosphate, two-step sintering was used and the purity was improved. We prepared aH-tricalcium phosphate by means of additive and analyzed the effect of the additive and the forming process of the production. During the comparing experiments of liquid we got the bone cement of 3 - tricalcium phosphate that P - tricalcium phosphate appeared adhesive bone cement slurry after adding the citric acid. We did a little work on CNTs/ 3 - tricalcium composite and found the CNT cluster with a shape of basket from the SEM graph of fracture surface.Secondly, the preparation procedure, microcosmic structures, mechanics and the strengthening effect of CF/CPC composite were investigated. The CF was oxidized in order to increase the combining strength of interface. We investigated CF surface after treated by IR and SEM and determined the best treatment procedure, that is, the CF was oxidized at 90°C for 2h by nitric acid. The composite contained 0.6% CF, its rupture strength was 10.14MPa increased by 53.1%, and its compressive strength was 20.81 MPa, increased by 6.66%, the porosity was 43.03%. CF was surrounded by the matrix and even formed crystal with the shape of lotus leaf affected by the Van der waals and hydrogen bond. As a result, the affinity between CF and the solid and the combination of the interface were improved. The debonding, pulling out and the fracture of fibers made composite mechanics improved. We calculated the strength in the theory of the composite strengthened by successive carbon fiber and found the composite could be improved ulteriorly.Thirdly, We researched the preparation procedure, microcosmic structures, mechanics and the effect of strengthening of CNTs/CPC, CF/CNTs/CPC and built the crystal growth model of the HA on CNT to set forth the existence form in the bone cement. In the study we found the "Hadley grain" in the bone cement for the first time. CNTs and the powder were milled at 300r/min for 4h, and then observed by SEM and TEM. The optimum percent of CNTs in the composite was 0.6%, whose rupture strength was 10.48MPa increased by 58.3%, compressive strength was 31.22MPa increased by 60.02%, and the porosity was 42.12%. The affection by adsorption of CNTs pore was analyzed. We set forth the procedure of the strengthening byanalyzing the surface and the properties of CNTs, and explained the existence the physical adsorption and chemical bond. As a result the combination was intense .The mechanics of composite was improved because of the fracture of the HA/CNT composite body and the turnaround of the crack. The calculated value of CNTs strengthening effect was greater than the experimental value, which showed the CNT has potential in strengthening materials. We prepared the CF/CNTs/CPC with the optimum percent of CF and CNTs, whose rupture strength and compressive strength were 40.5 IMPa and 15.78MPa, increased by 107.6% and 138.37% respectively. We can see that the cooperation of the two materials was better. We observed the microcosmic structures of the cements and the composite and found the "Hadley grain", 1 u m in wall, empty or with unreacted bone cement grains. The existence of the pores could affect the strength of the cements.The fourth, biocompatibility experiments of in vitro and in vivo were made to the bone cement material. The blood compatibility experiment in vitro indicated that good chemical property of the composite, physical and chemical microcosmic multiphase structure in 0.1-0.2 u m formed by hydrated matrix caused it wholly appeared no affinity with platelets, and possessed the property of anti-cruor. When we planted the material in the gluteus of white rat, it was found from histological observation that no large area of infection and putrescence of circumambient tissues was caused in the striated muscle, only normal inflammation. The composite showed no toxicity, and had good biocompatibility. After the New Zealand big white rabbit’s skull plantation, it was indicated by the bone conductibility experiment that 12 weeks after the composite was planted, blood vessels and bone tissues of surrounding organisms grew well towards the composite, the relate data of the composite obtained from CT already were in the scale of the normal bone structure, PWI and tissues observation had the same result. These evidences indicated that the composite had good osconductibility, which could provide the good support for new bone growth, and then it would be the potential material for bone tissue engineering.The study reported the CF/CPC strengthened by the long carbon fibers following the structure of the bone, CNTs/CPC strengthened by the carbon nanotubes withexcellent properties and CF/CNTs/CPC strengthened by the carbon fibers and the carbon nanotubes for the first time, and then researched the preparation procedure, microcosmic structures, mechanics and the effect of strengthening. It can be used to repair the defection of bone and substitute for the unbearing bone because of its high rupture strength.Besides the above three kinds of new composite improved the bone cement mechanical properties, we had several innovations and discovery. Firstly, we prepared the new type of ciH-tricalcium phosphate, analyzed its procedure and tested the mechanics and the microcosmic structures of the cements. Secondly, we found the novel existence form of CNTs in the composite that HA grew on CNT and formed HA/CNT by the physical adsorption and chemical bond. Thirdly, we found the "Hadley grain" by observed the microcosmic structures of the matrix after hydration, and pointed out the existence of the pores could affect the strength of the cements. Above reports could enrich the investigation and application of bone cement. So far, we have declared the national patent and explored along with several medical corporation.更多还原