Modification of Wood by Tannin-Furfuryl Alcohol Resins–Effect on Dimensional Stability, Mechanical Properties and Decay Durability

Abstract

Furfurylation is a well-known wood modification technology. This paper studied the effect of tannin addition on the wood furfurylation. Three kinds of dicarboxylic acids, adipic acid, succinic acid, and tartaric acid, as well as glyoxal as a comparing agent, were used to catalyse the polymerisation of furanic or tannin-furanic solutions during wood modification. Impregnation of furanic or tannin-furanic solution at a certain concentration into the wood followed with curing at 103°C for a specific duration was performed for the wood modification. Different properties of the modified woods like dimensional stability, resistance of treatment to leaching, mechanical properties, decay durability against white-rot (Coriolus versicolor, Pycnoporus sanguineus) and brown-rot (Coniophora puteana) as well as their chemical and anatomical characteristics were evaluated. Results revealed that the partial substitution of FA by the tannins improved the fixation of the chemicals impregnated in wood. Further, dimensional stability, leaching resistance, Brinell hardness, modulus of elasticity/modulus of rupture, and decay durability properties of the furfurylated wood were also improved in the presence of tannins. Scanning electron microscopy revealed the deposition of the polymer in the wood lumen cells and in the wood cell walls.