Epoxidised linseed oil as hydrophobic substance for wood protection : technology of treatment and properties of modified wood

Abstract: Public concern about the release of toxic compounds from wood-based products drives legislation towards enforcing industries to find and use more sustainable solutions for wood treatment. Plant oils are good alternatives to treat wood, minimizing or even neutralizing the impact on the environment. Wood modification with epoxidised linseed oil (ELO) and acetic acid as catalyst has proven a suitable method to impregnate and protect wood. However, the mixture presents a serious inconvenience because of the quick polymerization of the ingredients that limits its practical application. Therefore, this study was designed to evaluate an alternative method using a two-step process which bypassed the problem above. Several treatment options using this method onto Scots pine sapwood were tested. The results were evaluated by determining the dimensional stability, hydrophobic and mechanical properties of the treated wood. The studied treatments provided very good dimensional stability of the material, the measured anti-swelling efficiency (ASE) was in the range 40-57%. Reference samples of thermally modified wood showed only 40% ASE. The grafting of ELO to the wood polymeric constituents was studied using FT-IR spectroscopy. The modification influenced negatively the modulus of rupture, while the modulus of elasticity, hardness and compression strength of the material was almost unchanged. It can be concluded that the two-step process method seems a possible and feasible practical solution for ELO treatment of wood.