Tannic acid-polyethyleneimine modified ammonium polyphosphate: For efficient flame retardant and UV resistant of polylactic acid

In order to enhance the flame retardancy and ultraviolet (UV) resistance of Polylactic acid (PLA) composites, a series of cross-functional additives were meticulously designed. A novel integrated intumescent flame retardant (IFR) named TPAPP was synthesized by incorporating ammonium polyphosphate (APP) as the core material and polyethyleneimine (PEI) as a bridging agent to connect APP with tannic acid (TA). The incorporation of TPAPP into PLA composites effectively improved their flame retardancy and UV absorption resistance. When 5% TPAPP was added, the ultimate oxygen index of the PLA composite increased to 27.0%, achieving a UL-94 rating of V-0. Comparative to the neat PLA sample, the total heat release rate and total smoke emission were reduced by 17% and 77%, respectively. These results demonstrate the significant synergistic effect of TPAPP in enhancing the flame retardancy and UV resistance of PLA. Furthermore, this multi-functional additive strategy presents a promising avenue for achieving high-performance PLA composites.