School of Mechanical Engineering, College of Engineering, University of Tehran, Iran.
Université Sorbonne Paris Nord, CNRS, UPR3407, LSPM, Sorbonne Paris Cité, avenue Jean-Baptiste Clément, 93430, Villetaneuse, France.
J Mech Behav Biomed Mater. 2021 Dec;124:104768. doi: 10.1016/j.jmbbm.2021.104768. Epub 2021 Aug 13.
The present investigation explores the impact of Mg volume fraction (V) as a controlling parameter of degradation rate in designing patient-specific cardiovascular stents made of PLA/Mg composites. For the purpose of this research, PLA/Mg composite plates containing 1, 3, 5, and 10% V are produced by melt blending and hot press molding. Characterization techniques such as scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) are employed to study the microstructure of PLA/Mg composites. For in vitro corrosion tests, stent prototypes and composite samples are immersed in baths of simulated body fluid (SBF). According to in vitro corrosion tests, increasing V increases the corrosion rate of the composites by accelerating the corrosion of the particles and the crystalline zones surrounding them. In addition, a 2% raise in the Mg content (from 1% to 3%), increases the overall Mg weight loss by more than 4 times. Composite samples and prototype stents containing more than 5% V exhibit cracking and brittleness after 7 days of immersion in SBF. In light of the compression tests results and also the failures and cracks observed during immersions, the upper limit of Mg content for PLA/Mg stent fabrication purposes is found to be below 3%.
本研究探讨了镁体积分数（V）作为控制降解速率的参数，在设计由 PLA/Mg 复合材料制成的个体化心血管支架中的作用。为此，采用熔融共混和热压成型的方法制备了含有 1%、3%、5%和 10% V 的 PLA/Mg 复合板。采用扫描电子显微镜（SEM）、差示扫描量热法（DSC）和 X 射线衍射（XRD）等表征技术研究了 PLA/Mg 复合材料的微观结构。为了进行体外腐蚀试验，将支架原型和复合样品浸入模拟体液（SBF）浴中。根据体外腐蚀试验，随着 V 的增加，通过加速颗粒及其周围结晶区的腐蚀，复合材料的腐蚀速率加快。此外，Mg 含量增加 2%（从 1%增加到 3%），会使整体 Mg 重量损失增加超过 4 倍。在 SBF 中浸泡 7 天后，V 含量超过 5%的复合样品和原型支架会出现开裂和脆性。根据压缩试验结果以及浸泡过程中观察到的失效和裂纹，发现 PLA/Mg 支架制造中镁含量的上限低于 3%。
