Synergistic effect of hierarchically porous 4A zeolite on improving the fire retardancy and reducing the fire toxicity of ammonium polyphosphate treated wood composites

The synergistic effect of hierarchically porous zeolites on the fire retardancy and fire toxicity of ammonium polyphosphate (APP) treated wood composites was studied in this work. Hierarchically porous 4A (H4A) zeolite and 4A zeolite were hydrothermally synthesized and characterized. Several groups of wood composites containing APP as fire retardant and H4A/4A zeolites as synergists were fabricated. Thermogravimetric (TG) results showed that H4A zeolite increased the char formation and enhanced the thermal stability of APP treated wood at higher temperature. Cone calorimetry test results suggested that H4A zeolite reduced the heat release rate (HRR) and decreased CO produce rate (COPR) of APP treated wood composites. Moreover, H4A also exhibited better smoke suppression than 4A zeolite when the APP content was small. These results demonstrated that H4A zeolites may be a promising synergistic component for improving the fire retardancy and reducing the fire toxicity of APP treated wood composites.