Improved fracture toughness and ductility of PLA composites by incorporating a small amount of surface-modified helical carbon nanotubes

Abstract

To overcome the brittleness of poly (lactic acid) (PLA), worm-like helical carbon nanotubes (HCNTs) were selected as a novel additive to PLA in this work due to their unique morphology. To enhance the interfacial interaction with PLA matrix, a silane-coupling agent (3-aminopropyltriethoxysilane, KH550) is chemically grafted onto the HCNTs. Interestingly, a remarkable improvement in the ductility of poly (lactic acid) (PLA) composites is achieved by adding a small amount of KH550-treated HCNTs. The elongation at break and the impact strength of HCNT-KH550/PLA composite are 205% and 30% higher than those of pure PLA, respectively. The high orientation of PLA molecular chains and crystals is responsible for the remarkable enhancement in the tensile ductility. This strategy is believed to offer more possibilities for optimizing the mechanical properties of PLA composites.