Modification of Tannin-soy Based Adhesive Coordination with Plasma in Plywood

Tannin-soy based adhesive (SFT) was prepared with acacia tannin extract and soy protein, and properties of plasma modified poplar wood and pine wood were studied by the investigation of bonding strength and water resistance of plywood with SFT in this paper. The results indicated that bonding strength and water resistance of plywood with SFT improved obviously than that of soy-based adhesive, and crosslinking system formation of tanin-soy based adhesive and introduction of catechol groups may be the key. After plasma treating on surface of poplar wood and pine wood, contact angle decrease, surface energy increase, and wettability was improved. The bonding strength and water resistance of plywood combination plasma with SFT were significantly improved, and the increasing degree of pine-plywood was higher than poplar-plywood greatly. FT-TR and SEM results showed that the physical and chemical action happened on the wood surface after plasma treatment. Plasma could produce active groups on wood surfaces by the degradation of fiber and lignin of wood, and the wood surface was etched from the smooth into the coarse. In addition, the fats might oxide and degrade to some degree, and converted into what was conducive to adhesive and adhesion, which led to performance improvement of pine-plywood than that of poplar-plywood.