Bonding characteristics of Gigantochloa scortechinii

The adhesion and bonding properties of bamboo, Gigantochloa scortechinii, were studied. The variables studied were adhesive types, grain orientation (parallel-ply or cross-ply) and bonding properties of strips taken from different parts of bamboo culm, i.e. strips taken near the periphery or near the inner layer or a combination of both. Commercially available adhesives, phenol formaldehyde (PF), urea formaldehyde (UF) and melamine urea formaldehyde (MUF), were used to bond the bamboo strips. The bonded specimens were subjected to plywood shear test in both dry and wet conditions. The study showed that PF resin formulation suitable for the production of tropical plywood was found to be most compatible for bonding bamboo strips; nevertheless, a slightly longer press time is required to ensure sufficient curing of resin. All shear strengths and wood failure percentage of the PF-bonded laminates met the minimum requirement of British standards. The bonding properties of UF-bonded laminates achieved the standard only when tested in dry conditions. Hot press parameters employed for pressing the MUF-bonded laminates was not sufficed to cure the resin. The grain orientation (parallel or cross-ply) of the strips bonded with either PF or UF had no significant effect on the glue bond quality when tested dry. In extreme wet conditions, the parallel-ply laminates were apparently more stable than the cross-ply laminates. Different parts of the bamboo culm significantly affect the resulting glue bond quality. In all conditions, laminates made from peripheral strips gave more stable products than those made either from inner strips or from the combination of both.