Senatov F S, Niaza K V, Zadorozhnyy M Yu, Maksimkin A V, Kaloshkin S D, Estrin Y Z
National University of Science and Technology "MISIS", 119049, Leninskiy pr. 4, Moscow, Russian Federation.
National University of Science and Technology "MISIS", 119049, Leninskiy pr. 4, Moscow, Russian Federation.
J Mech Behav Biomed Mater. 2016 Apr;57:139-48. doi: 10.1016/j.jmbbm.2015.11.036. Epub 2015 Dec 15.
In the present work polylactide (PLA)/15wt% hydroxyapatite (HA) porous scaffolds with pre-modeled structure were obtained by 3D-printing by fused filament fabrication. Composite filament was obtained by extrusion. Mechanical properties, structural characteristics and shape memory effect (SME) were studied. Direct heating was used for activation of SME. The average pore size and porosity of the scaffolds were 700μm and 30vol%, respectively. Dispersed particles of HA acted as nucleation centers during the ordering of PLA molecular chains and formed an additional rigid fixed phase that reduced molecular mobility, which led to a shift of the onset of recovery stress growth from 53 to 57°C. A more rapid development of stresses was observed for PLA/HA composites with the maximum recovery stress of 3.0MPa at 70°C. Ceramic particles inhibited the growth of cracks during compression-heating-compression cycles when porous PLA/HA 3D-scaffolds recovered their initial shape. Shape recovery at the last cycle was about 96%. SME during heating may have resulted in "self-healing" of scaffold by narrowing the cracks. PLA/HA 3D-scaffolds were found to withstand up to three compression-heating-compression cycles without delamination. It was shown that PLA/15%HA porous scaffolds obtained by 3D-printing with shape recovery of 98% may be used as self-fitting implant for small bone defect replacement owing to SME.
在本研究中，通过熔融沉积成型3D打印技术制备了具有预成型结构的聚乳酸（PLA）/15wt%羟基磷灰石（HA）多孔支架。复合长丝通过挤出获得。研究了其力学性能、结构特征和形状记忆效应（SME）。采用直接加热激活形状记忆效应。支架的平均孔径和孔隙率分别为700μm和30vol%。在PLA分子链有序排列过程中，分散的HA颗粒作为成核中心，并形成了一个额外的刚性固定相，降低了分子迁移率，这导致恢复应力增长起始温度从53°C移至57°C。对于PLA/HA复合材料，在70°C时观察到应力发展更快，最大恢复应力为3.0MPa。当多孔PLA/HA 3D支架恢复其初始形状时，陶瓷颗粒在压缩-加热-压缩循环中抑制了裂纹的生长。最后一个循环的形状恢复率约为96%。加热过程中的形状记忆效应可能通过使裂纹变窄而导致支架“自愈”。发现PLA/HA 3D支架能够承受多达三个压缩-加热-压缩循环而不分层。结果表明，通过3D打印获得的形状恢复率为98%的PLA/15%HA多孔支架，由于其形状记忆效应，可作为小型骨缺损替代的自适配植入物。
