Tannin-modified soybean protein concentrate for wood adhesive

ESPÓSITO, L.; CIANNAMEA, E. M.; SOLABARRIETA, I.; PITER, J.C.; RUSECKAITE, R.A.; STEFANI, P.M.

Journal of Applied Research in Technology & Engineering

Universitat Politècnica de València

Año: 2022

Soybean protein concentrate (SPC) modified with condensed mimosa tannin (CT) were employed as eco-friendly andformaldehyde-free adhesives for glued-wood joints. Eucalyptus grandis wood boards free of knots and cracks were usedas substrate. Thermogravimetric analysis (TGA) showed that tannin provided higher thermal stability to the adhesive, whichallowed expanding the temperature range for hot pressing. Apparent viscosity and dynamic contact angle were measuredto evaluate the influence of tannin content on rheological behaviour and the wettability process. A classic shear-thinningbehaviour was observed for all the adhesives. Apparent viscosity and equilibrium contact angle reached a maximum valuefor low CT content. This effect was attributed to the existence of associative interactions between CT and SPC. Bondingquality parameters (wood failure percentage and shear strength) of the glued-wood joints were measured according toEN 302-1:2004 standard. SPC adhesive modified with 1 % w/w CT showed the best performance in dry conditions. Theseadhesives were suitable for glued-wood joints for indoor environments.