Mechanical properties, physical properties and fungal resistance of acetylated fast grown softwoods. I Small specimens

Abstract

Small samples of Sitka spruce (Picea sitchensis), lodgepole pine (Pinus contorta) and Japanese larch (Larix leptolepis) selected from normal commercial stock have been acetylated using the facilities of Stichting Hout Research in the Netherlands. The weight percent gains (WPG) used were 14% and 17% with the spruce, 16% and 19% with the pine and 17% with the larch. The acetylated materials were subject to three point bending to evaluate mechanical property change, three cycle anti-shrink efficiency (ASE) testing, equilibrium moisture content measurement and fungal resistance assessment using Coniophora puteana. Mechanical properties showed no significant change following acetylation. Equilibrium moisture contents were much reduced, although there was little difference between the pine at 16WPG and 19WPG. The repeated wetting and drying cycles of the ASE tests indicated that the chemical modification was permanent and the fungal tests showed very significant improvement in durability. Taken overall the results are mostly consistent with those obtained using slower grown Northern European softwoods, and substantiate the property improvement claims made for the acetylation process.