The effect of wood defects on chemical modification with acetic anhydride

Excerpt

Chemical modification of wood has been successfully employed to improve dimensional stability and decay resistance of both solid wood and wood based panels (Papadopoulos and Traboulay 2002; Papadopoulos and Hill 2003; Papadopoulos and Gkaraveli 2003). In all cases considered in the literature, chemical modification employed in small clear wood specimens. In many cases, samples with the same number of growth rings were preferentially chosen and carefully selected so that growth rings were parallel to the tangential face, to ensure rapid reagent penetration into the cell lumen (Papadopoulos and Hill 2003). However, deviations from normal structure are not common, since trees are living organisms and are subject to various influences throughout their life span. When wood is looked upon as a raw material, most abnormalities adversely affect its service value; these are commonly called defects (Panshin and DeZeeuw 1980). From the wood utilisation point of view, defects are also certain normal characteristics of all trees, namely knots and pith. Despite an exhaustive search of the literature, there was no studies published dealing with the modification of wood with defects. Consequently, the purpose of this paper was to look at the effect that some defects may have on chemical modification of wood. The defects studied here in were: false rings of pine wood (Pinus sylvestris), discontinuous rings of pine (Pinus nigra), compression wood of pine (Pinus sylvestris) and tension wood of beech (Fagus sylvatica). …