Interfacial reinforcement mechanism in poly(lactic acid)/natural fiber biocomposites featuring ZnO nanowires at the interface

Poly(lactic acid) (PLA)/natural fiber (NF) biocomposite is available from renewable resources and can degrade totally in the environment, but suffers from poor interfacial adhesion. Here, we adopted two-step hydrothermal method to functionalize zinc oxide (ZnO) nanowires on the NF surface driven by strong intramolecular interaction. The perfect integration of the root-like NF and PLA matrix via the laterally-grown ZnO nanowires enabled the corresponding composite to present excellent interfacial adhesion. This can be exemplified by the substantial increases of 157% and 403% in interfacial shear strength and the debonding energy compared to PLA/pristine NF composite. Finally, a comprehensive understanding on the interfacial reinforcement caused by the laterally-grown ZnO nanowires was elucidated based on finite element method and the fracture morphology after the single fiber pull-out test. This study can provide an interfacial manipulation strategy on topological architecture to improve the interfacial properties of the environmentally-friendly PLA/NF biocomposite, which is instructive to achieve the large-scale application. Keywords: Poly(lactic acid), Natural fiber, Interlocking interface, Hydrothermal method, Zinc oxide