Physicochemical properties of starch adhesives enhanced by esterification modification with dodecenyl succinic anhydride

Starch-based adhesives were prepared by esterification modification with dodecenyl succinic anhydride (DDSA) and polyaryl polymethylene isocyanate (PAPI) as a crosslinking agent. DDSA modified starch (DMS) adhesives could significantly enhance the viscosity and adhesion strength of starch adhesives, making it beneficial to be applied in the field of plywood industry. This paper investigated the physicochemical properties of starch modified by dodecenyl succinic anhydride. Solid content, viscosity, adhesion, structural change and morphological features were characterized in detail. Viscosity and solid content of the modified starch (MF) adhesives was improved remarkably when DDSA was introduced. Three-ply plywood was fabricated with DMS adhesives, and its wet shear strength was measured. The results showed that the water resistance of the adhesive with 6wt% DDSA improved by 72.4% compared to that without DDSA. The wet shear strength plywood bonded by the adhesive reached 1MPa and could meet the requirement set by the China National Standard. Incorporating DDSA into the starch adhesive formed a dense crosslinking structure due to chemical reactions between DDSA and active groups on the starch molecules and thus improve the water resistance of the cured adhesives. The introduction of DDSA improving the viscosity and solid content remarkably, which increased the amount of the adhesive that penetrated the wood surface and formed more interlocks. Using DDSA promoted a smooth and homogeneous fracture surface of cured adhesive, which effectively prevented water intrusion and improved water resistance. The modified adhesive proved practical as a plywood adhesive for industrial application.