Differently modified wood: comparison of some selected properties

Artikel i vetenskaplig tidskrift, 2004

To turn wood into a material with enhanced and less varied properties, many methods of chemical modification have been developed in the past few decades. In this work, the mechanical and physical properties of wood modified using nine methods were studied. The modification methods were acetylation, maleoylation, succinylation, furfurylation, modification with N-methylol acryl amide, modification with reactive linseed oil derivative, modification with methylated melamine resin, thermal modification in vegetable oil, and a combination of acetylation and modification with methylated melamine resin. The wood species used were Scots pine (Pinus sylvestris L.), beech (Fagus sylvatica L.) and birch (Betula pubescens Ehrh.). Both pure sapwood and heartwood specimens of pine were used. The following properties were studied: equilibrium moisture content, strength and stiffness in different climates, stiffness stabilization efficiency, antiswelling efficiency, impact bending strength and hardness. Acetylation and furfurylation were the most effective modification methods for achieving high dimensional stability, high stiffness stability and low equilibrium moisture content. The impact strength was reduced by all the methods, but to a varying extent. Acetylation, furfurylation and modification with methylated melamine formaldehyde resin led to a slight increase in bending strength. Furfurylation at high degrees of modification resulted in a substantial increase in hardness.