Abstract: The effect of different ratio between ammonium polyphosphate (APP) and modified 13X molecular sieves (MS) on combustion properties, thermal stability and smoke behavior of wood were investigated by cone calorimeter, TG-FT-IR analysis, SEM and other test method in present study. The results show that the composites have good synergistic effects while the ratio of APP and 13X molecular sieves is approximately 7:3. As a result, the combination of modified 13X molecular sieves and APP led to lower heat release rate (HRR). It's seen that a reduction of total heat release (THR) to 31.1%, and the total smoke production (TSP) and the mean of CO yield (m-COY) were decreased to 75.9% and 69.6%, respectively. Clearly, the modified 13X molecular sieves compound with APP promoted the thermal stability of the forming char. This exhibited an excellent flame retardant and smoke suppression characteristics. Besides, this compound had a catalytic oxidation for smoke and toxic gas produced by wood combust. This could reduce the concentration of CO effectively and further casualties were avoided.

Key words: modified molecular sieve, fire-retarding of wood, synergistic effect, smoke catalytic oxidation