Polenta cornstarch-mimosa tannin-based urea formaldehyde adhesives for interior grade particleboard
Résumé
This study investigated the physical properties (rheological and thermogravimetric) of adhesive mixtures of (i) polenta cornstarch, (ii) -mimosa tannin, and (iii) -urea formaldehyde (UF) and various mechanical properties (internal bond, modulus of rupture and modulus of elasticity, surface soundness and withdrawal of screws) of laboratory particleboard made with such adhesive mixtures. It was found that the best results were given with the mass ratio of 10:4:86 for polenta cornstarch, mimosa tannin and UF resin. Both, the polenta cornstarch and the mimosa tannin were introduced into the UF resin in order to replace a certain proportion of the UF resin. The laboratory results showed that particleboards bonded with the optimal mixture of polenta cornstarch, mimosa tannin and UF resin exhibited better mechanical properties than boards made from commercial UF resins. Rheological results show excellent structural stability of the mixture. The formaldehyde emission levels from the boards were lower by 18% to those obtained from boards bonded with the control UF. UF resins, hence, could be partially substituted by addition of polenta cornstarch and mimosa tannin barks extracts.