China Plastics ›› 2025, Vol. 39 ›› Issue (8): 94-99.DOI: 10.19491/j.issn.1001-9278.2025.08.015

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Preparation of piperazine phosphate⁃melamine phosphate flame retardant and its flame⁃retardant effect on polypropylene

Zhou Lei1,2()   

  1. 1.Chongqing Copolyforce New Materials Co,Ltd,Chongqing 401332,China
    2.Chongqing Research Institute co Ltd of China Coal Technology & Engineering Group Corporation,Chongqing 400039,China
  • Received:2025-01-27 Online:2025-08-26 Published:2025-07-30

Abstract:

A piperazine⁃melamine phosphate intumescent flame retardant (PMP) was synthesized via thermal condensation of piperazine diphosphate and melamine phosphate, and subsequently incorporated into polypropylene (PP) to prepare flame⁃retardant composites. The structure of PMP was confirmed by nuclear magnetic resonance (NMR) and Fourier⁃transform infrared spectroscopy (FTIR), with characteristic peaks at -10.45 (end⁃group P), -23.67 (middle P) in NMR, and 867.15 cm-¹ (P—O—P) in FTIR, indicating successful polymerization. Thermogravimetric analysis revealed excellent thermal stability, with PMP and flame⁃retardant PP exhibiting T1 % at 249.8 °C and 304.6 °C, T₅% at 297.3 °C and 388.8 °C, and residual weights at 800 °C of 44.84 % and 11.95 %, respectively. The flame⁃retardant performance of PP was improved with increasing piperazine diphosphate content, yielding higher limiting oxygen index (LOI), elongation at break, impact strength, and melt flow rate, but reduced tensile strength, flexural strength, and modulus. Higher PMP loading enhanced flame retardancy and LOI of PP but decreased its tensile strength, elongation, impact strength, and melt flow index, while increasing flexural strength, modulus, and density. Balancing flame retardancy, mechanical properties, and cost, the optimal PMP composition was 50 %~70 % piperazine diphosphate, with a recommended PP incorporation rate of 23 %~25 %.

Key words: intumescent flame retardant, piperazine phosphate, melamine phosphate, flame retardant polypropylene, copolymer?type flame retardant

CLC Number: