Thermoplastic behavior of wood powder compacted materials

To investigate the possibility and problems in recycling techniques for wood powder compacted material (WPCM) obtained by steam compression, a dynamic mechanical thermal analysis (DMTA) was conducted in dry and wet conditions. The results obtained show that mechanical properties such as the static Young’s modulus and bending strength of WPCM increased with an increasing steam temperature up to 170 °C during the compression of the wood powder. It is emphasized that WPCM having a bending strength of 80 MPa with a Young’s modulus of 8 GPa can be prepared by steam compressing of wood powder only due to a auto-condensation of wood components. The DMTA showed that the relative storage Young’s modulus of WPCM dramatically decreased in water exposure by heating, although it slightly increased in the dry condition. This indicates that WPCM is softened under heat in the presence of water, but it becomes harder by heating without water. The loss tangent peaks showed that the softening behavior of WPCM seems to result from lignin. Consequently, it is thought that WPCM can be shaped by compressing in water, and after obtaining the desired shape, the drying process should be conducted to fix the shape and harden the WPCM.