2021 Volume 57 Issue 4 Pages 145-151
This study investigated a nondestructive imaging method for morphological characterization of adhesive
bondlines in wood-based materials using X-ray micro-computed tomography（ CT）. Softwood and hardwood
plywood were prepared using phenol-formaldehyde resin adhesive（ PF）; hardwood glulam was prepared using
water-based polymer-isocyanate adhesive. These materials were scanned using six industrial X-ray CT apparatuses.
Each resulting scan was reconstructed into three-dimensional grayscale voxel data and saved as a
stack of grayscale slice images. In softwood plywood images with field of view（ FOV） of approximately 30 mm
diameter, tracheids and PF resin in tracheid lumen but were not clearly visualized. In contrast, in softwood
plywood images with FOV of 3.6 mm diameter, tracheids and PF resin in tracheid lumen were clearly visualized.
In hardwood plywood images with FOV of 3.6 mm diameter, PF resin in vessels and its crack were clearly
visualized, probably owing to resin shrinkage during solidification in the vessels. In hardwood glulam images
with FOV of 0.8 mm diameter, resin at the bondline and its internal heterogeneity were visualized. The developed
method realizes morphological observations in wood-based materials with FOV of several mm diameter
and can be applied to a wide variety of wood adhesion studies such as the investigation of the effects of morphological
characteristics on material strengths.
