Doctoral candidate : Joël Hamada
University : Université de Lorraine, France
Contract duration : 2014-2016

Research topic — Study, identification and characterization of the effects of the natural variability of the forest resource to optimize the quality of the heat-treated wood

Research team and supervising scientists —
Research teams : Research Unit for the Study and Research of Wood Materials – LERMAB

PhD supervisor : P. Gérardin (LERMAB)

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Context  — The thermal treatment of wood by soft pyrolysis is a preservation process with low environmental impact constituting an alternative to treating wood by impregnation of biocides. Depending on conditions of the treatment (time, temperature), the chemical composition of the different cell wall constituents is more or less modified influencing the properties of the material with regards to its durability against fungal attacks and its dimensional stability. One of the current barriers to developing this process on an industrial scale lies in the difficulty of making a product consistent in quality (durability, dimensional stability, color). These difficulties can be explained either by inadequate command of the treatment process or by specific wood inter and intra variability.

Objectives and research questions — To investigate the effect of the natural variability of wood (density, chemical composition) on the reactions of thermo-degradation occurring during heat treatment and properties conferred on the material contributing to the heterogeneity of the finished product as a raw material and that of the process itself.

Scientific and socio-economic issues — Understanding the thermo-degradation reactions of wood to further develop monitoring and prediction of the quality of heat-treated wood tools with a view to optimizing existing industrial processes and use of the resource

Methodological approaches and expected results —

Two levels of study are planned for different deciduous and coniferous species.

• At the level of the board: boards of oak from different silvicultural conditions with varying densities allow us to characterize how density effects the kinetics of thermo-degradation of wood and the properties of the material;

• At the level of the tree ring: separation at the level of the annual tree ring of earlywood and latewood, sapwood and heartwood, and thermogravimetric analysis allow us to characterize the behavior of these different fabrics relative to thermo-degradation reactions.

The results obtained should allow us to better predict the behaviour of wood based on its initial properties, allowing for improved control of the process and higher quality of heat-treated wood.