NaOH hydrothermally treated gibbsite modified silicone acrylic emulsion-based intumescent flame-retardant coatings for plywood

The gibbsite has been employed to design hybrid flame retardants, the directly hydrothermal pretreatment could enhance its reactivity in theory. Therefore, NaOH hydrothermally pretreated gibbsite is exploited to optimize silicone acrylic emulsion (SAE)-based intumescent flame-retardant coatings (IFRC) through a facile sol-gel method, it determines that the pretreated gibbsite holds superior flame resistance to pristine gibbsite. The hydrothermal condition of 4 mol·L −1 NaOH under 100 °C facilitates the transformation from gibbsite to boehmite, leading to the formation of growing hydroxyl and irregular microstructure, corresponding to the improved flame retardancy. The doped gibbsite/boehmite imparts an enhanced flame retardancy to the SAE-based IFRC, evidenced by the highest FRI of 2.05 with an FGI of 0.28 kW·m −2 ·s −1 compared with that of S0 (0.62 kW·m −2 ·s −1 ). Because the enhanced crosslinking of the newly formed boehmite constitutes the compact and continuous charring with an improved flame retardancy. It explores low-carbon recycling exploitation of bauxite residue for preparing organic-inorganic hybrid flame-retarding coatings, seeking an efficient approach to improving gibbsite‘s synergistic flame-retarding effect. • Hydrothermally pretreated gibbsite imparts enhanced flame retardancy of IFRCs. • The boehmite holds superior crosslinking reactivity in the IFRCs than the gibbsite. • The synergistic flame-retarding effect consists of catalytic charring, crosslinking, and dilution.