High performance flame-retardant bamboo scrimber via a core-shell synergistic strategy

Bamboo scrimber is an emerging construction material with high mechanical properties and excellent aging resistance, consist of disintegrated bamboo and phenolic resin (PF), but its flammability severely limits their application. Traditional flame retardant treatments have demonstrated limited flame-retardant efficacy and often compromise the mechanical strength of bamboo scrimber. To address this problem, this study proposes a "coreshell" synergistic flame-retardant strategy. This approach involves treating the PF network shell with organosilane-modified sepiolite (SSep) and the bamboo fiber bundles with a phosphorus-boron flame retardant (FR) system. The results showed that the total heat release of the treated bamboo scrimber (BS-FR-SSep9) decreased by 61.8 % and 39.5 % compared to untreated bamboo scrimber (BS) and FR treated bamboo scrimber (BS-FR), respectively. The limited oxygen index (LOI) of BS-FR-SSep9 increased from 32.8 % for BS to 50 %. Further analysis indicated that the FR system promoted the charring of bamboo fiber bundles, while SSep can enhanced the heat resistance of the PF resin and facilitated the production of a highly graphitized char, effectively protecting the underlying material. Additionally, SSep enhanced the mechanical properties of the bamboo scrimber, mitigating the adverse effects associated with flame retardant treatments. These results suggest that this synergistic strategy is promising for the development of high performance flame-retardant bamboo scrimber for construction and building applications.