Synthesis and characterization of a novel organic-inorganic hybrid char-forming agent and its flame-retardant application in polypropylene composites

• Published in: Journal of analytical and applied pyrolysis Vol. 134; pp. 231 - 242
• Main Authors: Xu, Bo, Wu, Xiao, Ma, Wen, Qian, Lijun, Xin, Fei, Qiu, Yong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2018
• Subjects: ammonium polyphosphates; burning; calorimeters; Char-forming agent; combustion; crosslinking; flame retardants; Fourier transform infrared spectroscopy; Hybrid; Intumescent flame retardant; nuclear magnetic resonance spectroscopy; oxygen; Polypropylene; polypropylenes; pyrolysis; Raman spectroscopy; scanning electron microscopy; silicon; smoke; solids; Synergistic effect; thermal stability; thermogravimetry; X-ray photoelectron spectroscopy; zinc oxide; Hybrid; Char-forming agent; Intumescent flame retardant; Synergistic effect; Polypropylene
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2018.06.013

•Novel organic-inorganic hybrid char-forming agent SCTCFA-ZnO was prepared and used for intumescent flame retardant PP.•APP/SCTCFA-ZnO presented higher-efficiency flame retardancy and smoke suppression performance than APP/SCTCFA/ZnO in PP.•APP/SCTCFA-ZnO exerted more excellent thermal stability and char-forming ability than APP/SCTCFA/ZnO.•APP/SCTCFA-ZnO promoted forming higher graphitic cross-linking structures containing more P, O, N and Si in char. A novel organic-inorganic hybrid char-forming agent (SCTCFA-ZnO) was synthesized and characterized by Fourier transform infrared spectrometry (FTIR) and solid state nuclear magnetic resonance (SSNMR). SCTCFA-ZnO was combined with ammonium polyphosphate (APP) to prepare intumescent flame retardant polypropylene (PP) composites. The flame retardancy and thermal degradation behaviour of composites were investigated by the means of limited oxygen index (LOI), vertical burning test (UL-94), cone calorimeter test (CONE) and thermogravimetric analysis (TGA). The flame retardant pattern and mechanism of PP composites were studied by thermogravimetric analysis/infrared spectrometry (TG-IR), scanning electron microscopy (SEM), laser Raman spectroscopy analysis (LRS), FTIR and X-ray photoelectron spectroscopy (XPS). The results indicated APP/SCTCFA-ZnO system with the mass ratio of 2:1 showed the best flame retardant properties and smoke suppression performance in PP composites. TGA results showed that APP/SCTCFA-ZnO could clearly improve the thermal stability of composites and promote the char residue formation. The residue analysis results further revealed higher graphitic cross-linking structures containing more P, O, N and Si in PP/APP/SCTCFA-ZnO consequently resulted in more obvious reduction of the combustion and smoke production than PP/APP/SCTCFA/ZnO.