Wright-Charlesworth Debra D, King Julia A, Miller Darinda M, Lim Cho Hui
Department of Biomedical Engineering, Michigan Technological University, Houghton, 49931, USA.
J Biomed Mater Res A. 2006 Sep 1;78(3):541-9. doi: 10.1002/jbm.a.30767.
Poly(L-lactic acid) (PLLA) has been used for fracture fixation devices, but its use is limited because of its poor biocompatibility and mechanical properties. The effects of extrusion, incorporation of hydroxyapatite (HA) and self-reinforced composites (SRCs) on the resultant mechanical properties of PLLA were examined. Samples were conditioned for up to 52 weeks in PBS at 37 degrees C. Extrusion did not adversely affect the mechanical properties of PLLA. After in vitro conditioning, a slight but significant reduction in the strain to failure and modulus was seen. HA (10-40%) by weight was evenly distributed into PLLA using an intermeshing twin-screw extruder. As ceramic content increased, the initial modulus increased but flexural strength decreased. After immersion, the modulus of all HA-PLLA blends was lower than PLLA. HA particles did not form a strong bond with the PLLA, which promoted easier degradation of the HA-PLLA matrix. SRCs showed a higher modulus and strength when compared to all materials except the modulus of 30 and 40% HA-PLLA composites before immersion. Water preferentially attacked the matrix of the composite, leading to more fiber pullout, but the fiber orientation maintained the advantages in strength and modulus up to 24 weeks in vitro.
聚（L-乳酸）（PLLA）已被用于骨折固定装置，但其应用受到限制，因为其生物相容性和机械性能较差。研究了挤出、羟基磷灰石（HA）的加入以及自增强复合材料（SRCs）对PLLA最终机械性能的影响。样品在37℃的PBS中放置长达52周。挤出不会对PLLA的机械性能产生不利影响。体外放置后，观察到断裂应变和模量有轻微但显著的降低。使用啮合双螺杆挤出机将10%-40%重量的HA均匀分布到PLLA中。随着陶瓷含量的增加，初始模量增加，但弯曲强度降低。浸泡后，所有HA-PLLA共混物的模量均低于PLLA。HA颗粒与PLLA没有形成牢固的结合，这促进了HA-PLLA基体更容易降解。与除浸泡前30%和40%HA-PLLA复合材料模量外的所有材料相比，SRCs表现出更高的模量和强度。水优先侵蚀复合材料的基体，导致更多的纤维拔出，但纤维取向在体外长达24周内保持了强度和模量方面的优势。
