Utilization of temperature kinetics as a method to predict treatment intensity and corresponding treated wood quality: Durability and mechanical properties of thermally modified wood

Abstract

Wood heat treatment is an attractive alternative to improve decay resistance of wood species with low natural durability. However, this improvement of durability is realized at the expense of the mechanical resistance. Decay resistance and mechanical properties are strongly correlated to thermal degradation of wood cells wall components. Mass loss resulting from this degradation is a good indicator of treatment intensity and final treated wood properties. However, the introduction of a fast and accurate system for measuring this mass loss on an industrial scale is very difficult. Nowadays, many studies are conducted on the determination of control parameters which could be correlated with the treatment conditions and final heat treated wood quality such as decay resistance. The aim of this study is to investigate the relations between kinetics of temperature used during thermal treatment process representing heat treatment intensity, mass losses due to thermal degradation and conferred properties to heat treated wood. It might appear that relative area of treatment temperature curves is a good indicator of treatment intensity. Heat treatment with different treatment conditions (temperature-time) have been performed under vacuum, on four wood species (one hardwood and three softwoods) in order to obtain thermal degradation mass loses of 8, 10 and 12%. For each experiment, relative areas corresponding to temperature kinetics, mass loss, decay resistance and mechanical properties have been determined. Results highlight the statement that the temperature curves' area constitutes a good indicator in the prediction of needed treatment intensity, to obtain required wood durability and mechanical properties such as bending resistance and Brinell hardness.

Control of wood thermal treatment and its effects on decay resistance: a review

“…For each wood specie, relative area seems to be correlated to WL due to fungal exposure. From Candelier et al (2015), with permission industrial site, but it needs to be investigated for different wood thermal modification processes and on an industrial scale.…”

“…The relative area, calculated from wood temperature curve, above 100°C till heating temperature, has been proved to be an indicator of heat treatment intensity. Candelier et al (2015) . ]) and for different process conditions, this relative area seems to be a good indicator to estimate the final product quality and more particularly its durability improvement after a thermal modification (Fig.…”

Color and FTIR Analysis of Chemical Changes in Beech Wood (Fagus sylvatica L.) after Light Steaming and Heat Treatment in Two Different Environments

“…The importance of the total time of exposure at temperatures above 100 °C (heating + actual heat treatment) has been emphasized by Candelier et al (2015), who found that the temperature kinetics during heat treatment may be used to quantify the treatment effectiveness. The relative area situated below the temperature curve up to 100 °C on the temperature/time diagram is a reliable indicator of the heat treatment intensity.…”

“…Color evolution during heat treatment is used to classify treated wood, as there are significant correlations of E values with treatment intensity, the mass loss, and the thermal process used (Candelier et al 2015). However, a correlation related to evolution of heattreated wood color, which is valid for a certain treatment method cannot be used to compare the color changes resulting from different methods.…”

Chemical Alterations of Pine Wood Lignin during Heat Sterilization

“…This weakness limits the possible applications of wood treated by this method. The reduction of these properties is correlated to the severity of the time and temperature of the treatment (Candelier et al 2015). An increase in lignin content reduces the tensile modulus and tensile strength of the composites; however, the flexural and torsional modulus are improved with increasing lignin content (Faruk and Sain 2015).…”