Synthesis of silicic poly carbonyl urea and its flame-retardant effect on polypropylene for char forming

  • Ying Ren
  • Linfei Wei
  • Wenmin Li
  • Dandan Yuan
  • Yunyun Yang
  • Xufu CaiEmail author


This paper researches the char forming and flame-retardant effect of silicic poly carbonyl urea (Si-PCU) in company with ammonium polyphosphate (APP) on polypropylene (PP). Si-PCU was firstly synthesized and represented by Fourier transform infrared spectroscopy, energy-dispersive analysis, thermogravimetric analysis and water contact angle. Then, the intumescent flame retardants, Si-PCU + APP, were added into PP. Their flame-retardant effects were studied by limiting oxygen index (LOI) test, UL-94 vertical burning and micro-combustion calorimetry (MCC). When the amount additions of PP, APP and Si-PCU were 70, 20 and 10%, the LOI value of these PP composites (PP-6) was reached 29.5 and UL-94 testing grade was V-0, besides the PHRR decreased 66% and THR decreased 34% compared with pure PP. Furthermore, the residual char layers’ microstructure and strength were researched by field-emission scanning electron microscope, wide-angle X-ray diffraction and laser Raman spectroscopy. They showed that PP-6’s char layer was denser and had higher strength than other PP composites. Finally, tensile tests illustrated that the addition of Si-PCU + APP could decrease the break strength and toughness of pure PP, but Si-PCU + APP/PP had better toughness than APP/PP.


Silicic poly carbonyl urea Ammonium polyphosphate Intumescent flame retardants Carbonized flame-retardant efficiency Polypropylene 



We thank the strong supports by the following: the Experiment Center of Polymer Science and Engineering Academy, Sichuan University.


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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2019

Authors and Affiliations

  • Ying Ren
    • 1
  • Linfei Wei
    • 1
  • Wenmin Li
    • 1
  • Dandan Yuan
    • 1
  • Yunyun Yang
    • 1
  • Xufu Cai
    • 1
    Email author
  1. 1.Department of Polymer Science and Materials, The State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengduChina

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