Abstract: In order to investigate the synergistic effect between phosphorous and boron elements,the flammability and pyrolysis characteristics of Pinus yunanensis with ammonium dihydrogen phosphate and borax were assessed by using limited oxygen index (LOI) method,wood stack method,cone calorimeter test and thermo-gravimetric (TG) analysis method,and the pyrolysis kinetics of the materials was analyzed by Kissinger and Flynn-Wall-Ozawa models.The results show that the combination of ammonium dihydrogen phosphate and borax has good synergistic flame retardant effect.When the mass ratio of ammonium dihydrogen phosphate to borax is 4∶1,the heat release rate(HRR),total heat release(THR) of the flame retarded wood are 62.8% and 56.5%,respectively,lower than those of untreated wood,and the LOI value reaches to 66.5%,and the combination of ammonium dihydrogen phosphate and borax improves the activation energy of Pinus yunnanensis calculated by Kissinger and Flynn-Wall-Ozawa methods,thus effectively enhancing the high-temperature stability,char-forming ability,and flame retardancy.

Key words: Pinus yunanensis, ammonium dihydrogen phosphate, borax, flame retardancy, pyrolysis kinetics