Inhibition and densification by inorganic particles in organic–inorganic hybrid fiberboards to enhance mechanical and flame retardancy performance

The demand for fire-resistant wood-based materials has grown in response to the increasing urban population density and the widespread construction of high-rise buildings. Inorganic hybridization is a promising strategy to impart hybrid properties to lignocellulosic composites. However, this approach usually leads to a deterioration of the mechanical properties of the resulting composites due to agglomeration of the inorganic particles and insufficient adhesion. In this work, microscopic inorganic particles (ground calcium carbonate, kaolin, fly ash) were pre-mixed with melamine-urea–formaldehyde resin adhesive to solve the agglomeration problem of inorganic particles in organic–inorganic hybrid fiberboards. Additionally, the inclusion of inorganic particles inhibited excessive resin penetration and densified the resulting board, ultimately improving the mechanical properties and flame retardancy of the fiberboards. This work provides a straightforward and scalable approach that enables the well-dispersion of inorganic particles and fosters a strong bonding between wood fibers and inorganic particles to produce high-performance organic–inorganic hybrid fiberboards with higher flame retardancy.