Thermal behavior and flame retardancy of poplar wood impregnated with furfuryl alcohol catalyzed by boron/phosphorus compound system

The objective of this work was to improve the thermal stability and flame resistance of furfurylated wood via preparing a new multifunctional catalyst system containing boric acid (BA) and ammonium dihydrogen phosphate (ADP). Here, poplar wood (Populus cathayana) was impregnated with furfuryl alcohol (FA)/BA/ADP solutions, followed by curing at 105 ℃ to form a hydrophobic FA resin network within wood. When the BA/ADP system catalyzed in situ polymerization of FA inside the cell wall, the thermal stability was greatly enhanced with the decreasing of the prominent peak of mass-loss rate, the decomposition temperature, and the volatile gases. The limiting oxygen index (LOI) value of the treated wood was as high as 34.4% and its flame retardancy was remarkably improved by suppressing the heat transfer and smoke generation and promoting the char formation during combustion. The flame retardancy index (FRI) value of BA/ADP-FA modified wood was improved by 217%, indicating a “good” flame retardant efficiency. The crosslinking structures like P-O-C and B-O-C bonds enhanced the thermal stability of char. Such resulted poplar wood with flame retardancy will be an excellent application prospect as engineering biomaterial.