镁合金薄片增强聚乳酸复合材料的制备与性能研究
发布时间：2018-08-14 12:26
【摘要】：为了克服聚乳酸或镁合金作为骨固定材料单独使用时的不足,本文采用热压成型方法制备了一种以镁合金薄片为增强体、以聚乳酸为基体的可吸收骨内固定复合材料,并对其弯曲强度、剪切强度和冲击韧性等力学性能及其镁片微弧氧化处理(MAO)的影响进行了研究,最后,探索了复合材料在模拟体液中的降解性能,研究表明：随镁片体积含量的增大,镁片未MAO处理的复合材料(un-MAO-复合材料)的弯曲强度、剪切强度和冲击韧性均逐渐增大,体积分数为60%时,分别为229.3MPa、 84.5MPa和222.4 kJ/m2。镁片MAO处理有效改善了复合材料(MAO-复合材料)的界面结合,弯曲过程中两相界面没有发生脱粘现象,冲击韧性有显著提高。复合材料制备过程中,粘流态聚乳酸进入镁片MAO陶瓷层表面微孔中,冷却后产生机械锁合作用,同时,两相热膨胀性能差别较大,制样冷却过程中产生的残余热应力会进一步增大复合材料两相界面机械锁合效果。理论计算表明,在三点弯曲试验过程中复合材料外表面聚乳酸受到的最大拉应力约为35MPa,与纯聚乳酸的抗拉强度接近(约40MPa),可认为拉应力是造成最外层聚乳酸弯曲断裂的主要原因。复合材料弯曲过程中两相界面处受到的最大切应力理论值约为0.4MPa,而复合材料中un-MAO镁片与聚乳酸界面剪切强度实测值为1.08MPa,说明界面处切应力只是界面脱粘的重要原因之一。在37℃模拟体液浸泡实验过程中,随浸泡时间的延长,un-MAO-复合材料弯曲强度快速下降,浸泡28天后聚乳酸与镁片分离；MAO-复合材料试样弯曲强度逐渐降低,浸泡28天后仍能保持完整,其剩余弯曲强度为64.9MPa,表明了镁片MAO处理能显著提高复合材料在模拟体液中的强度维持能力。纯聚乳酸浸泡液pH值逐渐降低,而MAO-复合材料在浸泡5天后浸泡液pH值才发生变化,逐渐升高。un-MAO-复合材料在常温浸泡7天后就开始释放氢气,而MAO-复合材料在浸泡28天后仍未释放氢气,说明镁片表面氧化层可以在较长时间内保护复合材料中的镁合金不被浸泡液腐蚀。MAO-复合材料中聚乳酸分子量在浸泡过程中逐渐降低,浸泡3周后,镁片表面有“龟裂状”裂纹产生。
[Abstract]:In order to overcome the shortage of poly (lactic acid) or magnesium alloy used as bone fixation material alone, a kind of absorbable bone fixation composite with magnesium alloy sheet as reinforcement and poly (lactic acid) as matrix was prepared by hot pressing method in this paper. The mechanical properties, such as bending strength, shear strength and impact toughness, as well as the effect of micro-arc oxidation (MAO) on magnesium sheet were studied. Finally, the degradation properties of the composites in simulated body fluid were explored. The results show that the bending strength, shear strength and impact toughness of the untreated MAO composites (un-MAO-) increase with the increase of the volume content of magnesium sheets, and the volume fraction of 60kJ / m ~ (2) is 229.3 MPA, 84.5MPa and 222.4 KJ / m ~ (2), respectively. The MAO treatment of magnesium sheet can effectively improve the interfacial bonding of the composite (MAO- composite). During the bending process, there is no debonding phenomenon at the interface of the two phases, and the impact toughness is improved significantly. During the preparation of the composites, the viscous polylactic acid (PLA) enters the micropores on the surface of the MAO ceramic layer of the magnesium sheet, and after cooling, the mechanical locking cooperation occurs. At the same time, the thermal expansion properties of the two phases differ greatly. The residual thermal stress in the cooling process will further increase the mechanical locking effect of the two-phase interface of the composite. Theoretical calculations show that, During the three-point bending test, the maximum tensile stress of polylactic acid on the outer surface of the composite is about 35 MPA, which is close to the tensile strength of pure PLA (about 40MPa). It can be concluded that the tensile stress is the main reason for the bending fracture of the outermost polylactic acid. The maximum shear stress at the interface of two phases is about 0.4 MPA, while the measured value of shear strength at the interface of un-MAO magnesium sheet and polylactic acid is 1.08 MPA, which indicates that the shear stress at the interface is only one of the important reasons for the debonding of the interface. During the immersion experiment of simulated body fluid at 37 鈩，
本文编号：2182859
[Abstract]:In order to overcome the shortage of poly (lactic acid) or magnesium alloy used as bone fixation material alone, a kind of absorbable bone fixation composite with magnesium alloy sheet as reinforcement and poly (lactic acid) as matrix was prepared by hot pressing method in this paper. The mechanical properties, such as bending strength, shear strength and impact toughness, as well as the effect of micro-arc oxidation (MAO) on magnesium sheet were studied. Finally, the degradation properties of the composites in simulated body fluid were explored. The results show that the bending strength, shear strength and impact toughness of the untreated MAO composites (un-MAO-) increase with the increase of the volume content of magnesium sheets, and the volume fraction of 60kJ / m ~ (2) is 229.3 MPA, 84.5MPa and 222.4 KJ / m ~ (2), respectively. The MAO treatment of magnesium sheet can effectively improve the interfacial bonding of the composite (MAO- composite). During the bending process, there is no debonding phenomenon at the interface of the two phases, and the impact toughness is improved significantly. During the preparation of the composites, the viscous polylactic acid (PLA) enters the micropores on the surface of the MAO ceramic layer of the magnesium sheet, and after cooling, the mechanical locking cooperation occurs. At the same time, the thermal expansion properties of the two phases differ greatly. The residual thermal stress in the cooling process will further increase the mechanical locking effect of the two-phase interface of the composite. Theoretical calculations show that, During the three-point bending test, the maximum tensile stress of polylactic acid on the outer surface of the composite is about 35 MPA, which is close to the tensile strength of pure PLA (about 40MPa). It can be concluded that the tensile stress is the main reason for the bending fracture of the outermost polylactic acid. The maximum shear stress at the interface of two phases is about 0.4 MPA, while the measured value of shear strength at the interface of un-MAO magnesium sheet and polylactic acid is 1.08 MPA, which indicates that the shear stress at the interface is only one of the important reasons for the debonding of the interface. During the immersion experiment of simulated body fluid at 37 鈩，
本文编号：2182859
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