Comparative study on the durability of heat-treated White Birch (Betula papyrifera) subjected to the attack of brown and white rot fungi

Abstract

The effect of heat treatment on decay resistance of white birch was evaluated for different incubation periods ranging from 2 to 12 weeks using three species of brown rot and one species of white rot fungus. The results of weight loss tests showed that the white rot fungus, Trametes versicolor, effectively degraded the untreated wood (73.5%). While the degradation of untreated wood by brown rot fungi species, Gloephyllum trabeum (11.6%) and Conifora puteana (6.2%), was considerably less compared to T. versicolor, the third brown rot fungi studied, Poria placenta, caused an appreciable degradation of the same species (52.4%). The results clearly showed that the heat treatment reduced the effect of fungi attack on white birch. Increasing the heat treatment temperature from 195 to 2158C resulted in reduction of weight loss, consequently, reduction in fungal attack. As an example, the weight loss reductions due to T. versicolor, P. placenta, G. trabeum and C. puteana attack was 62.2%, 71.3%, 89.6% and 100%, respectively, compared to the weight loss of untreated wood when it is heat treated at 2158C. Thus, these results confirmed that the heat treatment increased the biological resistance of white birch.

Effect of thermal modification temperature on the mechanical properties, dimensional stability, and biological durability of black spruce (Picea mariana)

“…Hakkou et al (2006) found a significant correlation between biological durability and the thermal modification temperature. Decay resistance tests conducted by MetsaKortelainen and Viitanen (2009) on the sapwood and heartwood of Scots pine and Norway spruce, which have been thermally modified at 170-230°C using the thermowood method, against soft and brown rot fungi, also confirmed that the increasing thermal modification temperature increases the decay resistance.The improvement of biological durability in different species of thermally modified wood was also reported by Kamdem et al (2002), Jones et al (2006), Calenego et al (2010), and Lekounougou and Kocaefe (2012). According to published data, there are several reasons for the increase in the biological durability of thermally modified wood.…”

“…and Lekounougou and Kocaefe (2012). The presence of high MC observed in some samples can be considered due to the fungal degradation explained by the oxidative degradation of carbohydrates with the release of water molecules as indicated by Zabel and Morell (1992) and Borrega et al (2009).…”

“…The behavior of the fungus depends on not only the processing temperature of the species used, but also the processing conditions. The work done by Lekounougou and Kocaefe (2012) showed that P. placenta fungus was not aggressive against Populus tremuloides thermal modified at 220°C. These results also showed that the behavior of P. placenta may not be the same for wood impregnated with copper compounds.…”

Effects of extractives on degradation characteristics and VOCs released during wood heat treatment

“…Many VOCs are produced and released during wood heat treatments. These compounds are mainly derived from volatile extractives and evaporable byproducts formed from the degradation of wood components (Lekounougou and Kocaefe 2012;Candelier et al 2013b). The devolatilization analysis is of great importance to better understand the wood thermo degradation mechanisms as well as controlling hazardous substance emissions in VOCs.…”

Assessment of Structural Differences between Water-Extracted and Non-Extracted Hydro-Thermally Treated Spruce Wood by NIR Spectroscopy

“…Three major components (cellulose, lignin and hemicelluloses) along with low molecular compounds are the major components of wood [1][2][3]. In order to understand wood degradation mechanisms taking place under natural environmental conditions (during material service life), many researchers have simulated accelerated ageing by using biodegradation factors, such as soft, brown and white rot fungi or termites [4][5][6]; thermal and hydro-thermal ageing [7][8][9] or weathering and UV light exposure [10,11].…”