Crystallinity and Reinforcement in Poly-L-Lactic Acid Scaffold Induced by Carbon Nanotubes

Abstract

Poly-L-Lactic Acid (PLLA) is a bioabsorbable implant material due to its favorable biocompatibility and inherent degradability, while the insufficient mechanical strength hinders its further bone repair application. In present work, carbon nanotubes (CNTs) were introduced into PLLA scaffolds fabricated via selective laser sintering. It was found that the crystallinity of PLLA increased considerably since CNTs could promote the orderly stacking of its molecular chains, thereby improving the mechanical strength of PLLA scaffold. Furthermore, the fracture surface analysis revealed that CNTs acted as a bridge across the cracks and hindered their further expansion. Moreover, CNTs pulled out from the matrix to consume a large amount of fracture energy, which enhanced the resistance to external forces. As a consequence, the compressive strength, Vickers hardness and tensile strength of the scaffold were enhanced by 22.7%, 58.8% and 17.6%, respectively. Besides, the cells exhibited good attachment, spreading and proliferation on the scaffold. This study demonstrated that PLLA/CNTs scaffold was a promising candidate as bone implant.