Papers by Author: Kozo Kanayama

Abstract: A uni-axial compression test of solid wood containing a melamine formaldehyde resin and moisture at a heating condition was carried out to investigate fluidity of solid wood aiming at application of wood-flow-forming with an acceptable pressure level. Results show that there is a preferable moisture condition for initiation of flow phenomenon of the resin-treated wood. Since the decrease in the flow stress of wood generating pronounced size change in the drying process was distinguished, there might be a positive effect of the non-equilibrium state in moisture on the ease in generation of flow deformation.

Abstract: To investigate the effect of the additive agents such as polyethylene glycols (PEGs), melamine formaldehyde resin (MF-resin) and phenol formaldehyde resin (PF-resin) on the flow deformability of solid wood, free compression tests during heating were performed. Various molecular weights ranging from 200 to 20,000 for PEGs and almost similar molecular weight around 380 for MF-resin and PF-resin were applied. It was found from the compression tests that the yield stress indicating wood cell deformation resistance was drastically decreased with smaller molecular PEGs in wood, whereas the initiation of flow behavior, which is derived from detachment/slippage between cells, occurred at lower pressure with larger molecular PEGs. For generating the flow behaviors of solid wood, smaller molecular resin/substance was not always suitable. Thermosetting agents also act as a plasticizer during heating and especially the PF-resin showed better softening effect as well as a promoter of flow behavior than the MF-resin with almost similar molecular weight. This indicates that it is important for generating flow behavior to consider affinity/compatibility of resin to wood constituents. A maximum flow deformation ratio in the tangential direction of wood reached 180 % when using PEG 20,000 and MF-resin as an additive agent. It was also demonstrated that using PF-resin and MF-resin deep cup products shaped by a backward extrusion process had a better size stability against water, steam, and acetone.

Abstract: Compressed wood has different grading structure in an annual ring from one of natural wood. This paper treats the relationship between grading structures and effective thermal conductivity of natural and compressed woods. The Lorentz function and the power function are assumed as grading patterns of thermal conductivity. The grading thermal conductivity shows smaller effective thermal conductivity than the homogeneous wood with same average density. The sharper grading pattern gives much smaller effective thermal conductivity. The grading pattern of compressed wood is assumed as a model with locally compressed region. The calculated effective thermal conductivity by the model agrees with the measured thermal conductivity.