Thermo-hygro-mechanical modification of plantation grown Melia dubia
摘要
Compared to traditional long rotation timber, the wood qualities of plantation timbers are generally inferior. Thermo-hygro-mechanical (THM) wood modification is an important environmentally friendly technique that can enhance density, color, and other important wood properties, making the wood suitable for higher-end products. This paper reports on THM modification studies conducted on M. dubia as a potential replacement for traditional wood species of furniture and joinery. For THM modification, the wooden specimens (38 mm thick) were steamed at temperatures 160 °C, 164 °C, 167 °C, 170 °C 180 °C and 200 °C, for 45 min followed by cold compression to final thickness of 25 mm. Compression set recovery (Cr %), density, equilibrium moisture content (EMC), color properties, strength properties in static bending, hardness under static indentation of raw as well as modified wood were evaluated. At lower steam temperatures (160 °C), higher compression set recovery (Cr) (22.8%), and, at higher steam temperature (200 °C), lower Cr (6.3%) was recorded. The density increased from 0.4 to 0.57 g/cm³, accompanied by a slight improvement in modulus of rupture, while modulus of elasticity showed a slight decrease of 5.3%. At higher steam temperature pre-treatments, higher reduction in hardness (67% at 200 °C) occurred. Lower EMC was recorded for the THM modified specimens. A reduction in lightness value (L*) was recorded (33.1%), whereas, an increase in yellowness (a*) (3.2%) and minor decrease in redness (b*) occurred. Thus, THM modification enhances Melia dubia, making it suitable, efficient alternative for the applications like construction, furniture, flooring.