Effect of Temperature and Bake-out on Formaldehyde Emission from UF Bonded Wood Composites

Abstract

This study analysis the effect of various temperatures (20, 35 and <TEX>$50^{\circ}C$</TEX>) on the formaldehyde emission from wood composites, which were particleboard (PB), medium density fiberboard (MDF), high density fiberboard (HDF) and laminated HDF (L-HDF) by Japanese desiccator method. Also, to reduce formaldehyde emission by wood composites, it has been suggested that undergo a bake-out conditions. On average, the level of formaldehyde emission increased many times with a <TEX>$15^{\circ}C$</TEX> increase in temperature from 20 to <TEX>$35^{\circ}C$</TEX> for PB, MDF, HDF and L-HDF, respectively. Formaldehyde emissions from wood composites could be expected to increase with increasing ambient temperature. At <TEX>$35$</TEX> for 28 days bake-out treatment of boards, the free formaldehyde emission reduced 67.8% (PB), 40.1% (MDF), 37.8% (HDF), and 35.2% (L-HDF). On the other hand, after the bake-out at <TEX>$50^{\circ}C$</TEX> for 28 days, the formaldehyde concentration decreased by 88.2, 66.9, 62.2 and 59.3% of the concentration before the bake-out for PB, MDF, HDF and L-HDF, respectively. An interesting of the bake-out treatment at <TEX>$50^{\circ}C$</TEX> after 14 days, formaldehyde emission grade of PB & MDF down <TEX>$E_2$</TEX> to <TEX>$E_1$</TEX>, and HDF & L-HDF down <TEX>$E_1$</TEX> to <TEX>$E_0$</TEX>.