The potential of treating thermally modified wood with melamine resin to improve the dimensional stabilization is tested in this research. Two different boards of poplar (Populus ssp.) were cut into two halves. One half of each board was thermally modified (T1 and T2) in a commercial process, the other half was used as untreated reference material. The material was thermally modified using the vacu³ process under vacuum and maximum temperatures of 210 °C and 230 °C. Ten samples of each material were impregnated with a solution of a commercially available methyloated melamine resin and dry-cured in a laboratory oven at a maximum temperature of 120°C. The anti-swell-efficiency (ASE) based on the swell rate was tested during ten cycles of repeated drying and wetting. The melamine treatment caused a higher bulking in the references than in thermally modified wood. The ASE of T1 was improved by secondary modification, whereas the ASE of T2 remained higher than that of the secondary modified material. The melamine treatment of thermally modified poplar yielded good results for solution uptake and weight percent gain, but the bulking was lower than expected. Reasons may be found in the same mechanisms providing good dimensional stability of thermally modified wood in the first place: The cell walls are more inaccessible for melamine oligomers due to hydrophobation resulting from thermal modification.

Download document (381 kb)
free for the members of IRG. Available if purchased.

Purchase this document