A Bio‐Based Crosslinkable Schiff Base for Enhancing Anti‐Dripping, UV Resistance, and Mechanical Properties of PLA Composites and Fiber

With a continuous growing concerns over energy crisis and the increasing demand for flame‐retardant materials in construction and insulation industries, flame‐retardant polylactic acid (PLA) as green polymer featuring high strength, sound insulation, and biocompatibility, have become potential alternative for safe application in scenarios. A major challenge in developing flame‐retardant PLA lies in its poor anti‐dripping performance, which is usually accompanied by deteriorated mechanical properties thus, hindering the fabrication of PLA fibers. In this work, a tannic acid‐derived superior multifunctional Schiff base (TBFe) was synthesized via a one‐pot procedure to impart piperazine pyrophosphate containing PLA (PLA/PAPP) anti‐dripping, ultraviolet resistance, and enhanced mechanical property. Incorporating only 1.0 wt% TBFe enabled the PLA composite to achieve anti‐dripping performance and reach a UL‐94 V‐0 rating. Meanwhile, the composite attained a high LOI value of 36%, with the peak heat release rate reduced by 46.7%. The TBFe increased the mechanical strength of PLA by 23% compared to PAPP/PLA composites, allowing the spinning of TBFe containing multifunctional PLA fibers. Furthermore, the modified PLA composites exhibited exceptional ultraviolet shielding performance, successfully restricting light transmission to a maximum of 0.1% across both the UVA and UVB regions. Insightful reaction to fire mechanism in the condensed phase revealed that the catalytic carbonization resulted from transition metal Fe component accelerated the cross‐linking of Schiff base upon combustion. Consequently, the rapid formation of a dense char layer effectively eliminated melt dripping. This robust physical shield significantly inhibited the transfer of combustible volatiles and heat. Ultimately, our research introduces an eco‐friendly strategy for fabricating versatile, drip‐resistant FRs additives tailored for PLA.