Preparation And Property Research Of Chemical Crosslinking Modification Of Soybean Meal-based Adhesive

To improve the water-resistance of soybean meal-based adhesive (SM-adhesive), three kinds of coupling agent, ethylene glycol diglycidyl ether (EGDE) and others used as crosslinking agent were introduced into the soybean meal-based adhesive. The effect of modification on the adhesion property was studied, and the enhancement mechanism was investigated. Meanwhile, the amount of amino group of macromolecular chain was regulated and controlled by adding chitosan into the adhesive system to improve the adhesion property, and demonstrate the enhancement mechanism. The main conclusions were summarized as followed:1. The silane coupling agent KH560 could improve the water-resistance adhesion property of the SM-adhesive. As the dosage of KH560 was 3 wt%, the water-resistance adhesion strength of plywood prepared by modified SM-adhesive was increased by 139%.2. The EGDE could significantly decrease the viscosity of SM-adhesive and increase the adhesion strength. The epoxy groups of EGDE could react with the amino group of soybean meal. Thus, the three-dimensional network structure would be formed, so the water resistance was improved and the viscosity of adhesive was significantly decreased. As the dosage of EGDE was 8 wt%, the wet shear strength was increased by 165%.3. The amount of amino group of macromolecular chain in the adhesive system was important for the occurrence of the degree of crosslinking reaction. The amount of amino groups on the chitosan was much higher than on the molecule of soybean protein. With the introduction of chitosan, the degree of crosslinking reaction was more completely, thus the water resistance of plywood bonded with the adhesive was improved significantly. As the dosage of chitosan was 4 wt%, the wet shear strength was increased by 25%.