Development of a coating-type flame retardant based on APP-acrylic resin incorporating wood-derived biochar for engineered wood applications

초록

The increasing adoption of wood as a sustainable construction material has given rise to concerns regarding its inherent flammability. This study proposes a novel approach to the development of an eco-friendly, waterborne intumescent flame-retardant coating, integrating ethanolaminemodified ammonium polyphosphate (ETA-APP) with wood-derived biochar (BC) within an acrylic resin matrix. The present study systematically investigated the functional synergy between ETA-APP and biochar, with a view to achieving enhanced flame resistance and environmental compatibility. Thermogravimetric and Py-GC/MS analyses revealed that ETA-APP promoted early acid-catalyzed dehydration and phosphate cross-linking, while biochar served as a carbon-rich scaffold, facilitating the formation of a robust P-N-C-rich char layer. The coating demonstrated a 49 % decrease in peak heat release rate (pHRR) and a 52 % reduction in total smoke release (TSR) when subjected to cone calorimeter testing (ISO 5660-1). This finding substantiates the efficacy of the coating in curtailing the generation of heat and smoke. Further analysis in the form of XPS and EDS mapping provided further evidence of uniform N/P dispersion and strong interfacial bonding. These outcomes are attributed to the enhanced compatibility resulting from the ethanolamine modification. Py-GC/MS analysis revealed the absence of free amine, formaldehyde, or heavy-metal-containing volatiles, thereby confirming the environmentally benign thermal degradation behavior of the material under investigation. It was confirmed that the cooperative interaction between ETA-APP and biochar enhances condensed-phase char integrity and improves flame-retardant efficiency, even at moderate additive loadings. The findings establish a sustainable coating strategy that couples high fire protection with low toxicity, offering promising applicability for engineered-wood and hybrid structural materials exposed to fire and aggressive environments.

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