Synergism of Phytic Acid Modified Piperazine Pyrophosphate and Zinc Borate in Flame‐Retardant Polypropylene

ABSTRACT

Based on the synergistic effects among phosphorus, nitrogen, and boron elements, this study developed a novel and highly efficient flame‐retardant system to enhance the fire safety of polypropylene (PP) during its application. An integrated intumescent flame retardant (IFR) was prepared via supramolecular self‐assembly by surface‐modifying piperazine phosphate (PAPP) with phytic acid (PA) and melamine (MEL), and was named PM@PAPP. Subsequently, it was combined with zinc borate (ZB) to prepare flame‐retardant PP composites. The PM@PAPP/ZB/PP composite exhibited excellent flame retardancy and smoke suppression performance. Specifically, the limiting oxygen index (LOI) of PP5 reached 35.3%, and its vertical burning test (UL‐94) rating was V‐0 level. The peak heat release rate (pHRR) was 91% lower than that of pure PP. The peak smoke production rate (pSPR) of PP5 decreased from 0.097 m ² /s for pure PP to 0.007 m ² /s, representing a reduction of 93%. Furthermore, thermogravimetric analysis (TGA) and Raman spectroscopy results confirmed that the synergistic effect of ZB and PM@PAPP promoted the formation of continuous and dense carbon layers. This study provides a new strategy for improving the flame‐retardant properties of PP and expanding its application in fields with strict fire safety requirements.