the optimum level of nano-wollastonite consumption as fire-retardant in poplar wood (populus nigra)

Fire-retarding properties of wollastonite nanofibers in poplar wood (populus nigra) were studied here. some physical properties such as water absorption, volumetric swelling and anti-swelling efficiency (ase) were also measured. specimens were prepared according to the iso 11925 specifications for the fire-retarding properties and according to the astm d4446 -2002 specifications for the physical properties. impregnation of wood specimens with nanowollastonite was carried out at consumption levels of 4, 6.3, 10 and 12%, using rueping method (empty-cell process) and compared with the control specimens. five fire-retarding properties were measured, including weight loss (%), ignition point (s), fire endurance (s), glow endurance (s) and carbonization area (%). the obtained results indicated that fire-retarding properties were significantly improved in the nw-treated specimens. furthermore, the nw-impregnated specimens gained higher dimensional stability. however, water absorption increased. heat-conductivity of wollastonite limited accumulation of heat at one spot, furthermore, it acted as a physical barrier to deter heat and mass transfer between the gas and the condensed phase, consequently, fire-retarding properties were improved.