<Original>Physical and Biological Properties of Chemically Modified Wood Before and After Weathering

Abstract

Physical and biological properties of several chemically modified woods were investigated before and after weathering. Thin wood blocks, prepared from sapwood of albizzia (Paraserianth.es falcata Becker.) and sugi (Crvptomeria japonica D. Don), were treated with acetic anhydride, propylene oxide, dimethylol dihydroxy ethylene urea (DMDHEU), and low molecular weight phenol formaldehyde resin (PF-resin). Outdoor (natural) exposure was made for 1 year, and accelerated (artificial) weathering was conducted for 1,080 hours in weather-meter, by irradiation of ultraviolet ray and water flashing. Weathering with the presence of water promoted the deterioration of wood under ultraviolet ray irradiation. From the results of color change, surface failure and weight loss of weathered specimens, acetylation and PF-resin treatments were ranked higher in protecting wood than propylene oxide and DMDHEU treatments. Enhancement of decay resistance and persistence against weathering were recognized in all treatments. The acetylation and PF-resin treatments were again better. Fast-growing and low-density albizzia may be promising for use outdoors following acetylation or PF-resin treatment.