Preparation and Performance Study of Pyrophosphoric Acid Piperazine and Tannic Acid Synergistically Intumescent Flame‐Retardant Polypropylene
To address the inherent drawbacks of polypropylene (PP), including high flammability, severe melt dripping during combustion, and significant mechanical property deterioration after flame retardant incorporation, a novel halogen‐free intumescent flame retardant (IFR) system was developed in this work by blending natural polyphenol tannic acid (TA) with piperazine pyrophosphate (PAPP). PP composites were fabricated via melt blending. Systematic characterization of the thermal stability, combustion behavior, mechanical properties, and char layer microstructure of the as‐prepared PP composites revealed that the limiting oxygen index (LOI) increased with an increasing PAPP/TA mass ratio. The optimal PP/7PAPP/TA formulation achieved an LOI of 37%. Compared with PP, the peak smoke production rate (pSPR) of the PP/7PAPP/TA composite decreased by 91.11%, while the peak heat release rate (pHRR) decreased by 90.66%. These results confirm that TA exerts a significant synergistic enhancement effect on the IFR efficiency of PAPP. Specifically, a PAPP/TA mass ratio of 7:1 enables the as‐prepared composite to achieve the optimal balance between flame retardant performance, melt dripping inhibition, and mechanical property retention.