Fire-retarding properties of nanowollastonite in MDF

Effects of wollastonite nanofibers on fire-retarding properties of medium density fiberboard were studied. Nanowollastonite (NW) was applied at 5, 10, 15, and 20 g/kg dry weight basis of wood fibers and compared with reference specimens. Two application methods of NW were used: surface application (SA), and internal application. Density was kept constant at 670 kg/m³ for all treatments. Specimens of 150 × 130 × 9 mm³ were prepared and fire-retarding properties were measured using two devices: slide fire test device and fixed fire test device. The properties included: weight loss, ignition and glowing times, width and length of the burnt area, and fire endurance. The obtained results indicated that most fire-retarding properties were significantly improved with the increase in NW-content up-to 15 %, including weight loss, ignition and glowing times, and fire endurance. Higher amounts resulted in decreasing of the properties which was partly due to the less fiber-content, and partly due to the absorption of resin by the wollastonite nanofibers. It can be concluded that SA of NW is more effective in improving fire-retarding properties of medium density fiberboard. Furthermore, 10 % of NW is recommended as an optimum level of consumption.