【作者】 何狄；

【导师】 汪涛；

【作者基本信息】 南京航空航天大学 ， 材料加工工程， 2008， 硕士

【摘要】 聚乳酸(Polylactide, PLA)是一种具有良好生物相容性、形状记忆效应的生物可降解高分子材料,现在主要运用于手术缝合和骨折修复。但纯聚乳酸制件的机械强度难与皮质骨相匹配;聚乳酸的降解中间产物呈酸性,容易引起人体无菌性炎症等问题,限制了其进一步应用。而纳米HAP(nano-Hydroxyapatite, n-HA)与PLA的复合,有望对此有所改善。本文采用水热法制备了纳米羟基磷灰石粒子(nHAP),研究了不同的表面活性剂、水热处理温度和时间、pH值对合成HA纳米粒子形貌、成分的影响。结果表明水热法制备HA纳米粒子工艺简单、成本低、适合大批量生产。采用KH550对纳米HAP进行了表面处理和改性,运用熔融共混法制备了纳米HAP/PLA复合材料。通过透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射分析(XRD)、能谱(EDAX)、傅立叶变换红外光谱(FTIR)等现代测试手段,对复合材料中nHAp的分散进行分析,并研究了纳米HAP的比例与表面处理对复合材料的力学性能和形状记忆性能的影响。试验结果表明,在纳米HAP含量低于30%时,经硅烷偶联剂KH550处理的纳米HAP能够均匀地分散在PLA基体中;随着纳米HAP含量的增加,复合材料的形状记忆性能有所下降;偶联剂的使用可以缓和这一趋势;当纳米HAP为30%时,复合材料的综合性能最佳,其缺口冲击强度为11.32kJ/m2,拉伸强度为75.4MPa,形状固定率为97.5%,形状回复率为94.5%。复合材料的降解实验表明,纳米HAP的存在可以缓解PLA降解所产生的酸性,在复合材料表面有球状磷灰石的聚积物。更多还原

【Abstract】 Polylactide(PLA) is a biocompatible and biodegradable polymer with shape-memory property, which has been widely used in fields of postoperative seam, and possibly applied in riveting of bone fractures. However, the further application of pure PLA has been restricted due to its poor toughness and the inflammation caused by its acidity during degradation. The composite of polylactide (PLA) and nano- Hydroxyapatite (n-HA) particle is supposed to resolve these problems.The synthesis of HA nanoparticles (nHAP) were studied by means of hydrothermal process in present work. The effects of different surfactants, pH value of the mixed solution, reaction temperature and time on the morphology and Ca/P molar ratio of nHAP were investigated also . The results show that the hydrothermal process is suitable for quantity production of HA nanoparticles due to its simplicity and low costs.The nHAP reinforced Polylactide(PLA) composites were prepared through melt commixing method with the nano-particle pretreated using KH550 coupling agent. Subsequently, The dispersion of nHAP in the PLA matrix, influences of nHAp content and surface modification on the mechanical and shape-memory properties of composites were characterized by means of TEM, SEM, XRD, EDAX and FTIR methods.The experimental results indicate that nHAP coupled by KH550 were uniformly dispersed in PLA at the contents lower than 30%. The optimal overall mechanical and shape-memory properties were obtained with the 30% nHAP/PLA composite, i.e. tensile strength 75.4MPa, impact toughness 11.32kJ/m2, shape fastness 97.5%, as well as shape recovery 94.5%. Furthermore, with the increasing nHAp content, the shape recovery and shape fastness decrease in comparison with pure PLA. Surface-coupling pretreatment of nHAP is able to postpone this trend. Finally, the in- vitro degradation results of the compsite show that nHAP can counteract the acidity caursed by the disassembly of PLA, and nHAP congregates at the form of spherical apatite.更多还原