Effect of Thermo-Treatment on the Physical and Mechanical, Color, Fungal Durability of Wood of Tectona Grandis and Gmelina Arborea from Forest Plantations

Abstract

This study evaluated the effect of thermo-treatment (THT) at 4 temperatures on the density, shrinking, mass loss, moisture absorption, color, durability in terms of resistance to decay, flexural strength, tensile adhesion of glue line and the infrared spectrum of the wood of Tectona grandis and Gmelina arborea. Sapwood, heartwood and radial and tangential grain patterns were studied. The results showed that the THT temperature decreases the density, the percentage of moisture absorption, the modulus of elasticity and modulus of rupture in the flexure test and the tensile adhesion of glue line. The percentage of shrinking and durability presented irregular behavior relative to the THT temperature. The percentage of mass loss increased with increasing THT temperature in both species. The total color change (∆E*) of thermo-treated wood (THTwood) also increased with increasing THT temperature. Sapwood of T. grandis and G. arborea, having clearer shades, showed a more noticeable color change compared to hardwood; however, no significant differences were obtained between some of the THT temperatures.

Physical and mechanical properties of thermally modified short-rotation wood in a closed system

“…For MOE, the 22% reduction was much higher than the 5% to 6% found by Menezes (2017), while Lengowski et al (2021) reported an increase of 24%. Finally, Méndez-Mejías and Moya (2018) reported the process had no significant effect on MOE even at 220°C, for both sapwood and heartwood.…”

“…For TMTW, reductions in MOR were also within the intervals reported in other studies with the same process and temperature, from 32% to 35% (Menezes 2017) to 50% (Lengowski et al 2021). For another process, Méndez-Mejías and Moya (2018) reported a 40% reduction in MOR for the lowest temperature assessed (205°C). For MOE, the 22% reduction was much higher than the 5% to 6% found by Menezes (2017), while Lengowski et al (2021) reported an increase of 24%.…”

“…Compared to Eucalyptus grandis , fewer studies have been carried out about the mechanical resistance of thermally modified Tectona grandis wood. For MOR in static bending, only reductions have been reported, from 32% to 35% (Menezes 2017), 40% (Méndez-Mejías and Moya 2018), and 50% (Lengowski et al 2021). For MOE in static bending, Menezes (2017) reported reductions from 5% to 6%, depending on the previous wood quality, and Lengowski et al (2021) observed an increase of 24%.…”

Chemical Composition and Color of Short-Rotation Teak Wood Thermally Modified in Closed and Open Systems

“…This has led some researchers to study the suitability of TM to darken and homogenize the color of teak wood from short-rotation plantations as a means of its valorization [14,15]. Since color is one of the most important wood properties for the wood market, other authors also studied the effect of TM on the teak wood color [16][17][18][19][20][21]. However, the majority of the studies used open-system processes [15][16][17][18][19][20], whereas few studies used different processes, such as thermo-vacuum [14] and pressurized closed systems [21].…”

“…Since color is one of the most important wood properties for the wood market, other authors also studied the effect of TM on the teak wood color [16][17][18][19][20][21]. However, the majority of the studies used open-system processes [15][16][17][18][19][20], whereas few studies used different processes, such as thermo-vacuum [14] and pressurized closed systems [21].…”