▎ 摘　　要

It is crucial to enhance the mechanical properties to realize the application of sodium alginate (Alg) in engineering materials. Herein, a Ca2+ cross-linked sodium alginate/graphene oxide (CAlg/GO) composite fiber with a secondary reinforcement structure was prepared via wet spinning. The microstructure and physical properties of the fibers were characterized by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, and mechanical strength testing. The composite fiber's strength and toughness improved significantly, benefiting from the uniform distribution of GO in the Alg matrix together with the simultaneous cross-linking of Ca2+ to Alg and GO sheets. Accompanying the addition of GO reaching 15%, the strength increased by 184 +/- 16%. Meanwhile, the CAlg/GO composite fiber possessed a significant improvement in flame retardancy; the limiting oxygen index increased from 33 to 37 after adding 10% GO sheets to the fiber. In addition, the composite fiber's reinforcement, toughening, and flame retarding mechanisms were discussed from the point of the interaction between Alg, GO, and Ca2+, as this study will provide data and theoretical reference for the application of high-performance CAlg/GO composite fiber.