本研究探討混料式射出螺桿對聚乳酸 (Polylactide, PLA)添加58S生物玻璃 (58S Bioglass, 58S BG)複合材料於微型拉伸試片之機械性質影響，並進行生物相容性測試。使用混料式螺桿直接射出成形(M-PLA/BG) 改善先前研究之雙螺桿混煉造粒後射出成形 (TV-PLA/BG)因高溫導致的熱降解作用。以實驗設計 (DoE)搭配單流向 (Ref)與雙流向 (WL)的微型拉伸試片，探討複合材料的顆粒分佈情形與機械強度差異，進行生物體外試驗評估應用於骨科醫材的可行性。實驗結果顯示，低熔融溫度 (Tmelt)因材料熱降解較少獲得較高的楊氏模數。添加10wt% BG的單流向試片有最佳楊氏模數為17,363 MPa，雙流向試片因縫合線處強度衰弱且顆粒容易應力集中，楊氏模數下降至15,892 MPa。雖然TV-PLA/10BG試片的平均顆粒間距(Inter-particle distance)為0.0526 mm，相較於本研究之M-PLA/10BG試片(0.1222 mm)，更接近於顆粒間距理想值(0.0506 mm)；然而TGA結果指出，M-PLA/10BG的熱裂解溫度提升約13~23℃，顯示其更好的熱穩定性，且楊氏模數由14,005 MPa提升至17,363 MPa。生物體外試驗方面，使用最佳射出成形參數(R7) 製作M-PLA/10BG迷你骨螺釘與骨板，浸泡於模擬人體體液(SBF)一周後，表面羥基磷灰石沉積物覆蓋率達91.35%。另外，生物相容性試驗結果顯示，迷你骨螺釘與骨板的細胞存活率分別是75.64%與80.12%，有助於成骨細胞增殖，本研究成果未來可更進一步探討生物醫療之應用。

This study investigates the effect to mechanical properties of miniature tensile specimens which consist of polylactide (PLA) with 58S bioglass (58S BG) composites under mixing screw injection molding. Furthermore, this study compares to our previous research results, i.e., the particle distribution, mechanical properties, and with/without weld line design of twin-screw (TV-PLA/10BG) and mixing-screw (M-PLA/10BG) miniature tensile specimens by Design of experiments (DoE) method. In vitro bioactivity and biocompatibility tests have been performed to assess the feasibility for potential orthopedic materials application. Results have shown that the significant factor is the melting temperature (Tmelt) for reducing degradation of PLA composites by injection molding. Higher Young's modulus of no-weld line specimens can be obtained in lower melting temperature factor, which is 17,363 MPa by adding 10 wt% bioglass. On the other hand, weld line specimens only reaches to 15,892 MPa of Young's modulus due to the weld line weakening the strength of specimens. The average inter-particle distance of M-PLA/10BG sample is 0.1222 mm, and the TV-PLA/10BG sample has better uniformity as 0.0526 mm. However, the M-PLA/10BG sample has better thermal stability, in which decomposition temperature increases by 13~23 °C, Young's modulus increases from 14,005 MPa to 17,363 MPa. For in vitro test, after immersing the M-PLA/10BG (R7) samples in simulated body fluid (SBF) for one week, the coverage of apatite deposition reaches to 91.35%, and the cell survival rate of bone screw is 75.64% and bone plate is 80.12%, which show positive results to osteoblasts proliferation. Results of this study can be expected to further development and applications of biomedical devices.

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