INFLUENCE OF WOOD ANATOMY ON THE DISTRIBUTION OF GUANIDINE BASED FIRE RETARDANTS IN FIVE FAST GROWING JAPANESE HARDWOODS

This study investigates the influence of wood anatomy on the distribution of fire retardant chemicals in five fast-growing Japanese hardwood species (Melia azedarach, Toona sinensis, Choerospondias axillaris, Alnus japonica, and Liriodendron tulipifera). Given Japan's increasing demand for sustainable and locally sourced materials, fire retardant treatments are critical for enhancing fire resistance in fast-growing hardwoods used for construction. Using low vacuum scanning electron microscopy (SEM), we examined the distribution of fire retardants in cross-section, radial section, and tangential sections, comparing the effectiveness in ring-porous versus diffuse-porous species. Results revealed that diffuse-porous species (Alnus japonica and Liriodendron tulipifera) retained higher levels of fire retardants with a more even distribution. In contrast, ring-porous species (Melia azedarach, Toona sinensis, Choerospondias axillaris) showed the highest chemical concentration at the edges.