押出成形した自己強化ポリ乳酸製骨固定スクリューの力学的特性に対するリン酸三カルシウム添加の影響

抄録

A tricalcium phosphate (TCP)/poly(lactic acid) (PLA) composites have attracted the attention as bone fixation screws in the maxillofacial region because of their bioabsorbability and osteoconductivity. However, the application of TCP/PLA composites has been limited to the low-loaded region because of their low strength. Therefore, molecular orientation in PLA was focused since improve the strength of TCP/PLA composites in this study. TCP/PLA screws were prepared through kneading, casting, and die forging. Effect of TCP content and drawing by the die forging on shear and torsional strength of TCP/PLA screws was investigated. The extruded screws were prepared through kneading and casting at 200 °C by using a single-screw extruding machine. The drawn screws were prepared through kneading, casting, and die forging. Casting billets were molded at 200 °C by using the single-screw extruding machine. Then, these billets were extruded at drawing temperature 130 °C and draw ratio 2 and molded simultaneously into the screws by die forging. The annealed screws were prepared by heating to 130 °C and pressing the extruded screws. As a result, the screws with different molding methods showed distinctly different fracture behavior. In 0 mass% of TCP content, shear and torsional strength of the annealed and the drawn screws were higher than that of the extruded screws. On the other hand, in 30 mass% of TCP content, the torsional strength of the drawn screws was higher than that of the annealed screws.