Resistance of birch wood modified with sorbitol-citric acid to white-rot decay and weathering

From the paper

Abstract

Abstract The increasing interest in sustainable and bio-based wood modification strategies has led to growing attention in enhancing durability. This is particularly important for wood with low durability and thus requires improvement for exterior applications. This study evaluates the decay and outdoor weathering resistance of silver birch ( Betula pendula ) wood modified with a sorbitol-citric acid (SorCA) system. Birch wood samples were vacuum-pressure impregnated with aqueous solutions of SorCA at 20% and 40% w/w and cured at 140°C. The distribution of the modifying agent within the wood structure was examined using X-ray microtomography, which confirmed effective penetration with partial or complete filling of wood lumina by the in-situ formed polyester network. The modified samples were subjected to ten months of natural weathering, mold exposure under high humidity conditions, and also to white-rot fungi ( Trametes versicolor ). Outdoor weathering results indicated improved resistance to surface deterioration in modified wood, although increased color change (ΔE) was observed due to the formation of chromophoric groups during curing and subsequent photodegradation. SorCA modification significantly improved decay and mold resistance, especially at higher concentrations. In general, SorCA modification showed great potential to improve the durability of birch wood with enhancing the biological durability and weathering resistance.