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Caractérisation des transformations physico-chimiques intervenant lors de la thermodégradation du bois. Influence de l'intensité de traitement, de l'essence et de l'atmosphère

Abstract : Thermal treatment is based on biopolymer chemical degradation by heat transfer, without additional chemical products impregnation. This process improves the dimensional stability and the decay resistance of wood. These improvements come at the expense of wood mechanical properties of wood which weak. Several types of heating processes exist currently differing mainly by the nature of the inert atmosphere used during treatment. The durability of this new wood material is correlated to the degree of polymers thermal degradation depending on the conditions and the treatment intensity. A conducting heat treatment pilot using nitrogen or vacuum and allowing dynamic record of mass loss is used to understand better the atmosphere influence. The results show that utilization of vacuum permit the elimination of volatile products formed during heat treatment and accumulated in oven, leading to lower extractives and Klason lignin contents due to the non recondensation of thermal degradation products. Limitation of the formation of recondensation products generates a lower mass loss for same treatment intensity and explains the lower polysaccharides degradation during a vacuum process. Fine chemical analyses and the study about thermal degradation reaction kinetics have allowed confirming the higher sensibility of hardwood than softwood to thermal degradation. In addition, these analyses have permitted the volatile thermal degradation products identification related to the treatment intensity. Subsequently, results have shown a higher thermal sensibility of lignin than holocelluloses for temperatures below 230°C. This work is a significant increase in basic knowledge about the mechanisms of wood thermal degradation and their relations with the processing parameters
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Kévin Candelier. Caractérisation des transformations physico-chimiques intervenant lors de la thermodégradation du bois. Influence de l'intensité de traitement, de l'essence et de l'atmosphère. Alimentation et Nutrition. Université de Lorraine, 2013. Français. ⟨NNT : 2013LORR0166⟩. ⟨tel-01750346⟩

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