The changes in color and dynamic modulus of elasticity of five important Indonesian tropical wood species after 10?months of outdoor exposure

摘要

Environmental conditions affect the natural weathering that leads to changes in wood characteristics. This study was conducted to evaluate physical and color changes and to predict changes in the mechanical properties of uncoated wood after outdoor exposure for 10?months (300?days). Five commercially important tropical wood species from Indonesia were used in field tests in this study, namely sengon or albizia ( Paraserianthes falcataria ), meranti or shorea ( Shorea spp.), mahoni or mahagony ( Swietenia spp.), teak ( Tectona grandis ), and merbau ( Intsia spp.). Moisture content, wood density, and color change, as well as the ultrasonic wave velocity and dynamic modulus of elasticity, were evaluated every month. After 2?months of exposure (60?days), color totally changed (Δ E *?>?12) for all species except merbau, which underwent changes in the fourth month (120?days). Wood became darker during the experimental period, with the exception of merbau wood, which became lighter by the end of 10?months. Shorea and teak were sensitive to color change as a function of the length of exposure. The wood species and length of exposure also significantly affected both ultrasonic wave velocity and dynamic modulus of elasticity.