Comparison of the effects of acetylation and paraffin emulsion impregnation in Pinus caribeae

The use of wood as building material has some disadvantages, especially in relation to water and dimensional stability. Wood modification methods have been studied in the past decades, including active methods such as acetylation and passive methods such as paraffin impregnation. Acetylation is very effective in avoiding water exchange in wood, but its large scale application is costly and capital demanding. Impregnation with paraffin emulsion could be a simpler and cheaper substitute method. In this context, this study had the objective to compare wood modification results of these two different methods. Pinus caribeae lamellas were acetylated and impregnated with wax emulsion in two different particle sizes. The modified slats were tested for water absorption in submersion, where the apparent contact angle was measured for distillate water, the thermal stability was tested by thermogravimetric analysis, color parameter was evaluated and near infrared (NIR) and visible light spectra were collected and segregated by principal component analysis (PCA). The particle size influenced the penetration of wax into the wood. For particle size 9 µm, the water absorption was similar to untreated wood, and similar to acetylated wood, particle size 3.9 µm. The external wax cover on the slats retained contact angles similar to acetylated wood, and higher than in untreated wood. The wax content in the slat influenced the thermogravimetric behavior of the modified wood, similar to lower equilibrium moisture content in acetylated wood. All treatments resulted in color changes of the wood surface. The principal component analysis was effective in segregating the acetylated wood from other treatments, and the different wax content in treated slats resulted in segregation of both paraffin waximpregnated woods. Paraffin emulsion impregnation could be a substitute for acetylation when reduction min water absorption was required.