Effects of Heat Treatment on the Physical Properties and Stress Wave-Based Dynamic Modulus of Elasticity of Camphor Wood (Cinnamomum camphora): A Response Surface Methodology Approach
Abstract
This study investigated the effects of dry-air and hydrothermal heat treatments on the physical properties and stress wave-based dynamic modulus of elasticity (DMOE) of Camphor wood (Cinnamomum camphora) using response surface methodology (RSM). Dry-air treatment was conducted at 150 – 200 °C for 10 – 20 h, whereas hydrothermal treatment was performed at 120 – 150 °C for 60 – 120 min. Equilibrium moisture content (EMC), air-dry density (AD), and stress wave-based DMOE were determined after treatment. Treatment temperature and duration significantly affected the measured properties, although their relative importance varied between the two treatment methods. Increasing treatment severity generally resulted in reductions in EMC, AD, and DMOE. Response surface models adequately described the relationships between the processing variables and the measured responses. Multi-response optimization was subsequently used to identify suitable treatment conditions by considering EMC, AD, and DMOE simultaneously. The optimized conditions differed between the dry-air and hydrothermal processes, reflecting differences in their responses to treatment temperature and duration. The results demonstrate the potential of stress wave-based DMOE as a rapid, non-destructive indicator for characterizing changes in the dynamic stiffness of heat-treated Camphor wood and provide a basis for selecting suitable thermal modification conditions for this species.
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