Thermal and pyrolysis analysis of minerals reinforced intumescent fire retardant coating

•Synergistic effects of kaolin clay and wollastonite on thermal performance of intumescent fire retardant coatings have been investigated.•IFRC-5 showed the substrate temperature 113°C after 1h fire test and char expansion 8.5 times higher compared to the control formulation.•A 5wt% increase of fillers in the formulation IRFC-5, carbon contents in char residue increased to 50.67% and oxygen contents reduced to 27.73%.•Pyrolysis GC–MS confirmed the fillers reduced the gaseous products from 3.4e+07 to 1.08e+07 in IFRC-5.•The fillers in IFRC-5 increased the residual weight up to 46.5wt.% from 31wt.%. This study presents the results of intumescent fire retardant coatings (IFRCs) developed to investigate the synergistic effects of mineral fillers (clay and wollastonite) based IFRC towards heat shielding, char expansion, morphology, composition, gaseous products and residual weight. The fire test has been performed to study the heat shielding effect of IFRCs on the substrate using UL-1709 standards. The results showed the synergistic effect of clay and wollastonite using 5wt.% enhanced the fire protection, performance with recorded substrate temperature 113°C after 1-h fire test. Field Emission Scanning Electron Microscopy (FESEM) and High-Resolution Transmission Electron Microscopy (HRTEM) showed the micrograph of compact char structure that increased char integrity due to the presence of inorganic fillers. X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) results showed the presence of boron phosphate, silicon phosphate oxide, aluminum borate in char that improved the thermal performance of IFRC up to 800°C. X-Ray Photoelectron Spectroscopy (XPS) confirmed that 5wt% (IFRC-5) of clay and wollastonite increased the carbon content up to 50.67%, lowering oxygen content to 27.73% in the char that enriched the fire resistance performance of the coating. Pyrolysis-Gas Chromatography-Mass Spectrometry (Pyrolysis GC–MS) confirmed that formulations IFRC-5 released less gaseous product concentration compared to IFRC-C and maximum reduction in gases was recorded from 3.4e+07 to 1.08e+07. Thermogravimetric analysis (TGA) demonstrated in residual weight was increased to 46.45% for IFRC-5 which resulted in the high thermal stability of the coating.