【作者】 倪自丰；

【导师】 葛世荣；

【作者基本信息】 中国矿业大学 ， 机械设计及理论， 2009， 博士

【摘要】 超高分子量聚乙烯(UHMWPE)具有良好的生物相容性、化学稳定性、抗冲击性、耐磨性及耐腐蚀性,是较为理想的医用高分子材料。然而,在长期的应用过程中,氧化、磨损以及磨屑积聚,易引起骨质溶解,发生无菌松动,从而加重了患者的痛苦,降低了人工关节的使用寿命。本文选用医药级UHMWPE粉末和天然维生素E为原料,采用模压成型法制备出UHMWPE/VE复合材料,并对其进行γ-射线辐照交联处理,最终得到抗氧化、耐磨损辐照交联UHMWPE/VE新型人工关节材料。常规气氛模压成型会在UHMWPE内部残留有气孔缺陷,从而降低了其力学性能和生物摩擦学性能;低真空环境下模压成型能有效地消除UHMWPE内的气孔缺陷,从而增加了其力学性能,提高了其生物摩擦学性能。辐照交联提高了UHMWPE的综合力学性能和抗磨粒磨损性能,但交联度的增加会降低其塑性;VE掺杂能有效地降低UHMWPE在辐照交联过程中的氧化程度,提高其疲劳性能,但过高浓度的VE掺杂会显著降低辐照交联UHMWPE的交联度,从而降低其力学性能和生物摩擦学性能。UHMWPE在辐照过程中会产生大量的残留自由基,这些残留自由基会与氧发生反应,从而导致UHMWPE氧化降解。加速老化后,辐照交联UHMWPE的力学性能和生物摩擦学性能显著降低;由于VE掺杂能显著提高辐照交联UHMWPE的抗氧化稳定性,加速老化前后,其力学性能和生物摩擦学性能变化并不明显。模压成型UHMWPE试样的表面晶体结构平行于表面排列。辐照交联增加了UHMWPE的结晶度,提高了其晶体结构致密度。加速老化后,辐照交联UHMWPE样品表面出现了大量的晶体结构断裂现象,而辐照交联UHMWPE/VE样品表面的晶体结构并未发生明显变化。表面是受外界环境因素作用最直接的部位,也是直接与空气中氧发生接触的部分。加速老化后,UHMWPE试样的表面硬度和表面弹性模量都有所增加,而其本体硬度和本体弹性模量都有所降低。辐射交联增加了UHMWPE的抗蠕变性能,降低了其对载荷变化的响应灵敏度。加速老化后,辐射交联UHMWPE的抗蠕变性能有所降低;而辐照交联UHMWPE/VE的抗蠕变性能降低并不明显。辐照交联提高了UHMWPE的表面自由能,增强了样品的润湿性;少量的VE掺杂并没有改变辐照交联UHMWPE的表面自由能和润湿性。UHMWPE的吸水率非常低,辐照交联和VE掺杂都会进一步降低其吸水率。在模拟体液中浸泡6个月后,辐照交联UHMWPE/VE试样中VE的含量并没有发生明显变化。人工髋关节磨损模拟试验结果表明,辐照交联UHMWPE/VE髋臼的耐磨损性能有了显著地提高;同时,辐照交联UHMWPE/VE能有效地控制磨屑的尺寸,减少了磨屑数量,并降低了由磨屑而引起细胞不良反应的程度,对于提高人工关节的可靠性和稳定性具有重要的意义。更多还原

【Abstract】 Ultra-high molecular weight polyethylene (UHMWPE) has excellent biocompatibility, chemical stability, impact resistance, wear resistance and corrosion resistance, and it is more desirable to the medical polymer materials. However, during the long-term application process, oxidation, wear and wear debris accumulation easily lead to osteolysis and aseptic loosening, which increase the suffering of patients, and limit the longevity of artificial joints. In this paper, medicine class UHMWPE powder and natural vitamin E were used as raw materials to prepare UHMWPE/VE composites by thermal compression molding method, and then they were irradiation crosslinked byγ-ray. Eventually, anti-oxidation and wear-resistant irradiation crosslinked UHMWPE/VE was made as a new type of artificial joint materials.Conventional atmosphere molding method will lead to the formation of residual internal porosity defects inside UHMWPE, which resulting in a decrease of its mechanical properties and biotribological properties; while low-vacuum environment molding method can effectively eliminate the internal porosity defects inside UHMWPE, and increase its mechanical properties and biotribological properties.Irradiation crosslinking could improve the comprehensive mechanical properties and the abrasive wear resistant properties of UHMWPE, but the increase in degree of crosslinking will reduce its plastic. VE doping can effectively reduce the oxidation of UHMWE in the process of irradiation crosslinking, improving its fatigue performance. However, high concentrations of VE doping will reduce the crosslinking degree of radiation crosslinked UHMWPE, which will reduce the mechanical properties and biotribological properties.Irradiation crosslinking results in the formation of a large number of residual free radicals existing inside the UHMWPE, which will react with oxygen. As a result, the extent of oxidation degradation is very serious during accelerated aging process. After accelerated aging, the mechanical properties and biotribological properties of irradiation crosslinked UHMWPE reduces significantly, while the VE doping can significantly enhance the anti-oxidation stability of irradiation crosslinked UHMWPE, and the change of its mechanical properties and biotribological properties is not obvious.The crystal structure of the surface of compression molded UHMWPE parallel to the surface of the specimen. Irradiation crosslinking improves the crystallinity of UHMWPE, increases the density of its crystal structure. After accelerated aging, there have been a large amount of fracture phenomena of crystal structure on the surface of irradiation crosslinked UHMWPE sample; while the crystal structure on the surface of irradiation crosslinked UHMWPE/VE sample has not changed significantly.The surface is the site which is affected by environmental factors most directly, and also in direct contact with oxygen in the air. After accelerated aging, the hardness and elastic modules of the surface of UHMWPE specimen increased, while the bulk hardness and bulk modulus of elasticity reduced.Irradiation crosslinking increases the anti-creep properties of UHMWPE, reduces its sensitivity to load response. Accelerated aging will lower the anti-creep properties of irradiation crosslinked UHMWPE; while the performance of irradiation crosslinked UHMWPE/VE has not changed obviously after accelerated aging.Irradiation crosslinking increases the surface free energy and enhances the wettability of UHMWPE, and a small amount of VE doping does not change its surface free energy and wettability. Water absorption of UHMWPE is very low, irradiation crosslinking and VE doping would further reduce its water absorption. After immersed in simulated body fluid for six months, VE content in irradiation crosslinked UHMWPE/VE does not show a significant change.Hip simulation test results indicate that the wear performance of irradiation crosslinked UHMWPE/VE improves significantly. Furthermore, irradiation crosslinked UHMWPE/VE could effectively control the size of wear debris, decrease the number of wear debris, as well as the extent of adverse reactions of cell caused by wear debris, and finally improve the reliability and stability of artificial joints.更多还原