Impacts of impregnation with boron compounds on the bonding strength of wood materials

The objective of this research was to evaluate bonding strength of poly(vinyl acetate) (PVAc), polyurethane based Desmodur-VTKA (D-VTKA), phenol–formaldehyde (PF) and melamine–formaldehyde (MF) adhesives to impregnated wood materials. For this purpose, oriental beech (Fagus orientalis lipsky), white oak (Quercus petraea spp.), Uludag fir (Abies bornmülleriana Mattf.) and poplar (Populus nigra) woods were impregnated with borax (Bo), boric acid (Ba), Bo + Ba (wt:wt 50:50%), mixture of di-ammonium phosphate (D), [D-(Bo + Ba)]:[w:w 50 + (25 + 25%)] and tanalith-C 3310 (T-C 3310) using the vacuum method according to ASTM-D 1413-76. The bonding strength test was applied to connection surface of samples jointed by four different adhesives. The highest bonding strength 12.72 N/mm2 was obtained from beech control samples. The lowest 6.06 N/mm2 was obtained from oak wood treated by T-C 3310 solution. In conclusion, boron compounds did not affect the bonding strength, but acidic impregnating materials significantly decreased this strength.