Mechanical and physical properties of plywood bonded with Bio-based Soy-tannin adhesive

Presently, because of the human health issues related to the formaldehyde gas emission initiated from traditional wood adhesives like urea formaldehyde, the bio-sbased adhesives has shown a good solution for preventing health hazards for human and the environment. To achieve an acceptable approach in wood based composites production, these adhesive need to qualify different standard limitations. This research was conducted to improve the bio-based soy-tannin adhesive for producing plywood with acceptable properties. For this goal, different adhesive formulations were prepared in the laboratory and they were treated at different temperature (40, 60, 80 ºC). Poplar wood plies with 2 mm nominal thickness were used to produce plywood specimens. The results showed the effectiveness of adhesives with heat pre-treatments at different temperature on shear strength (dry and wet) of plywood specimens. The highest shear strength of plywood specimens was achieved for 40 ºC treated adhesive in both dry and wet condition. Based on the results of shear strength test, all manufactured plywood specimens successfully met EN-314-2 standards requirement. Also, the results of delamination test revealed that plywood specimens which prepared by 40 ºC treated adhesive can successfully use for indoor condition, based on ANSI-HPV-1 requirements.