Résumé
Water movement and diffusion in wood is a well-documented research topic. It is strongly linked to the physical and mechanical properties of wood, and thus it has a high degree of importance and prominence for real-life application, particularly in wood drying. Here we employed the terahertz (THz) spectroscopy and imaging techniques to study the diffusion of water in wood. For our first experiments, we used balsa, a species of wood with a relatively homogenous structure (at the tissue level) and a low density that turns into fast diffusion rates and low absorption of the terahertz beam. This enables us to conduct several consecutive observations from various conditions (angles, diffusion directions, etc.) in a short time. These preliminary studies confirm the feasibility of terahertz spectroscopy and imaging techniques as a tool to observe the water diffusion in wood as a function of the direction (Fig. 1). We have also measured the evolution of the attenuation coefficient of the terahertz beam on wet and drying wood at different times. A model of the diffusion behavior based on these measurements, and according to the water content, will be developed and compared with other conventional water diffusion models based on gravimetry methods for the identification of the diffusion coefficients.