Shear Strength and Microscopic Characterization of a Bamboo Bonding Interface with Phenol Formaldehyde Resins Modified with Larch Thanaka and Urea
The aim of this study was to understand the microscopic characteristics of the bamboo bonding interface with phenol formaldehyde resin modified with larch thanaka and urea (PTUF) and its effect on the shear strength of two-ply bamboo laminated lumber. Bleached and carbonized bamboo strips were used, and two assembly patterns (outer-to-outer and inner-to-inner) were adopted to make two-ply bamboo laminated lumber with PTUF. The microstructure of the bonding interface and the bond-line thickness were investigated using a scanning electron microscope. The average depth and effective depth of PTUF on bamboo surfaces were evaluated by fluorescent microscopy characterization. The shear strength of two-ply bamboo laminated lumber was also examined. The results revealed a shallow depth of penetration of PTUF into the bamboo surface that was distributed primarily in the broken cell cavities formed during preparation, as well as between the cell walls. When the assembly pattern was inner-to-inner, the depth of penetration and bond-line thickness were higher, but the shear strength was lower than that of the outer-to-outer pattern. The carbonized bamboo laminated lumber provided a greater resin penetration and bond-line thickness, but lower shear strength, than the bleached bamboo laminated lumber.
Shear Performance of Adhesive Bonding of Cross-Laminated Bamboo
AbstractTests were conducted of the bonding shear strength of different bamboo configurations in terms of grain direction, adhesive, and clamping pressure. The bonding shear tests were carried out ...
Characterization on bamboo bonding interface by fluorescent track
The bonding interfaces of carbonized bamboo and bleached bamboo were stained and located by using toluidine blue.Then we optimized the gray value diversity and spectral background noise of interface and conducted the contrast experiments by changing stain concentration and staining time by using image analysis technology.The results showed that toluidine blue staining carbonized bamboo was better than bleached bamboo,and they both got the best parameters at 0.5 % fluorescent dye and 30 min staining time.It was also confirmed from the 3D gray image that there was a great difference of the gray value diversity from three-dimensional view between adhesive and substrate,and it is more suitable to calculate the average penetration depth of the bonding interface by the fluorescent staining.