Construction of a continuous flame-retardant network made from wood in epoxy resin

Transparent wood has the potential to be a sustainable alternative to glass in the building and construction industry. However, it is crucial to consider the fire hazard in building applications. In this study, we applied a green strategy to treat the wood aerogel with an intumescent flame retardant coating. The coating consisted of positively charged polyethyleneimine (PEI) and melamine, as well as negatively charged phytic acid. The treated wood aerogel demonstrated excellent flame retardancy. Subsequently, we incorporated the flame-retardant wood aerogel into epoxy resin to examine its impact on the thermal stability and fire resistance of the epoxy. The wood aerogel, with two bilayers of PEI + melamine/phytic acid, significantly enhanced the fire resistance of the epoxy. This was evident through notable reductions in peak heat release rate (42%) and total heat release (15%). By characterizing the char residue of the epoxy/wood-2 composite, we observed the formation of a continuous network within the epoxy matrix, effectively impeding the transfer of combustible gases and heat. Our work presents a simple and environmentally friendly approach to producing multifunctional transparent wood.