| 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.
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