Enhanced flame retardancy of modified β-cyclodextrin doped silica fume-based geopolymeric coating covered on plywood

A novel β-cyclodextrin (β-CD)/silica fume-based coating is prepared by sol-gel method to seek ecological and environmentally friendly flame retardants, which is employed for flame-retarding plywood extensively used as the decorative materials. The flame-retarding mechanism is elaborated through microstructure characterizations and pyrolysis kinetics. The results show that an appropriate dosage of γ-aminopropyl triethoxysilane modified β-CD (1 wt%) enhances the flame retardancy of the geopolymeric coating, the peak of heat release rate decreases from 125.95 kW·m−2 to 59.65 kW·m−2, the flame retardancy index climbs from 1 to 4.06. Because of the hydrogen-bonding crosslinking, filling, and subsequent adsorption, the coating transforms into an interpenetrating network, compact, and non-combustible layer during firing, thus blocking the transfer of heat or mass, leading to an increase in the pyrolysis Eα (it rises from 132.1 to 185.5 kJ·mol−1 at 1000–689 °C) according to the three-level chemical reaction model (F3). It explores an efficient approach for designing Si/C hybrid fireproof coatings with biomaterials and metallurgical solid waste, promoting the development of green flame retardant technologies.