Influence of acid and base on modified soy-based adhesive's water-resistant bonding strength

The defatted soy flour was processed by acid,base and acid-base to preparing modified soy-based adhesives,which were used on pressing three layers plywood,and its water-resistant bonding strength was tested by the request of China National Standard Plywood type Ⅱ.The results illuminated that the water-resistant of modified soy-based adhesives improved by acid or base' s processing.When the usage of acid was 11.9,the higher water-resistant bonding strength of plywood which pressed with modified soy-based adhesive was 0.48 MPa;and the usage of base was 22.6,the water-resistant bonding strength was 0.43 MPa.The acid-base as soy-based adhesives' modifier better than single acid or base,when the usage of acid and base were 11.9 and 39.9,the best water-resistant bonding strength of plywood was 0.61 MPa.The infrared spectrum analysis showed that as the modifiers of soy-based adhesives acid-base gather the merit of single acid or base modifying soy proteins,and improving the water-resistant of modified soy-based adhesive more effectively.