Effect of the Brazilian thermal modification process on the chemical composition of Eucalyptus grandis juvenile wood: Part 2: Solubility and ash content

Abstract

This article reports continuation of a study of the influence of the Brazilian process of thermal modification called VAP HolzSysteme ® on the chemical composition of eucalyptus wood. Flatsawn boards of Eucalyptus grandis juvenile wood were tested for four treatment levels: untreated, and thermally modified at final cycle temperatures of 140 °C, 160 °C or 180 °C. Chemical analyses were carried out according to the standards of the Technical Association of the Pulp and Paper Industry and encompassed 1% NaOH solubility and ash content. The 1% NaOH solubility increased in the wood thermally modified at 140 °C and 160 °C in relation to the untreated wood, but did not increase further 180 °C, indicating that the treatment at 180 °C was not enough to cause more degradation of hemicelluloses. In practice, the thermal modification process had no effect on the ash content of wood. The statistical difference observed between the treatment levels untreated and 160°C (0,04 percentage points) can be attributed to the heterogeneity of wood as a material.

Impact of thermal modification on swelling and mechanical behavior of Couratari spp.

“…These modifications alter the color of the wood, increase dimensional stability, reduce hygroscopicity, and increase resistance to microbiological attack (Severo et al 2016). The positive effect of thermal modification on wood decay is evident in the literature (Altgen et al 2019;Brito et al 2019), as well the changes on chemical composition (Esteves and Pereira 2009;Srinivas and Pandey 2012;Batista et al 2016;Severo et al 2016). However, there may be a reduction in the strength properties (Korkut 2012) and reversibility in hydrophobicity gains (Čermák et al 2016).…”