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[Display omitted] • An IFR containing acid, carbon, and gas sources was prepared by in-situ calcination. • HRR, EHC, THR, and TOC of fabric with IFR were less than those without IFR. • Carbonization process and fireproof mechanism of IFR on fabric were studied. A novel macromolecular carbon-nitrogen-phosphorous (C-N-P) intumescent flame retardant (IFR) containing acid, carbon, and gas sources was prepared by calcining polyphosphate (APP), pentaerythritol (PER), and melamine (MEL) through the direct heating method. The carbonization and expansion behaviors of IFR were investigated by testing the products of IFR, using nuclear magnetic resonance, X-ray photoelectron spectroscopy, transmission electron microscope, and scanning electron microscopy, at 360 °C, 450 °C, and 600 °C. Conjugated double bonds polymerized the nitrogenous polyaromatic structures as polyphosphate decomposed into phosphoric acid and diphosphate. Noncombustible gases released by MEL increased the internal pressure of the viscoelastic materials to make it expand. At temperatures below 450 °C, MEL promotes the formation of nitrogenous polyaromatic structures in the material, thereby optimizing the IFR char layer structure. The heat release rate, effective heat combustion, total heat release, and total oxygen consume of the IFR coated fabric were less than those of an uncoated fabric by 18%, 5%, 16%, and 13%, respectively, reducing the risk of fire hazard. The foam char formed during the burning of an IFR coated fabric controls the fabric's oxidation process and prevents its shrinking. [ABSTRACT FROM AUTHOR]

• Addition of MgAlCO 3 -LDHs and CaAlCO 3 -LDHs improved thermal insulation of IFR coating. • Metal ions from LDHs were chelated with carbon materials to form 3D reticular char. • LDHs can delay oxidation and improve degradation performance of char layers. MgAlCO 3 -layered double hydroxides (LDHs) and CaAlCO 3 -LDHs were respectively added as a synergistic agent to intumescent fire retardant (IFR) coatings. The 2.4 wt% of MgAlCO 3 -LDHs and the 6.7 wt% of CaAlCO 3 -LDHs were found to possess the best thermal insulation according to the fire performance tests. Further characterization by a cone calorimeter shows that the MgAlCO 3 -LDHs are superior to decreasing the specific extinction area of IFR coating, and the CaAlCO 3 -LDHs are advantageous in some other properties such as heat release rate, effective heat combustion and total heat release. Moreover, the X-ray diffraction (XRD) results infer that the flame retardant of char layer is primarily dependent on the amorphous structure formed after exposure to fire, the X-ray photoelectron spectroscopy (XPS) measurements of O 1s , C 1s , P 2p and N 1s reveal that the LDHs fillers suppress the oxidation of the IFR coating, and the Fourier transform infrared spectroscopy (FTIR) tests demonstrate that the LDHs protect the bridge frame structures. It is concluded that the LDHs can prevent the degradation and improve the thermal insulation of IFR coatings. [ABSTRACT FROM AUTHOR]