Preparation and analysis of environment-friendly and high- performance cellulose-based wood adhesive.

Conventional wood adhesives such as urea-formaldehyde (UF) resin, phenol-formaldehyde (PF) resin, melamine-formaldehyde (MF) resin, and melamine-urea-formaldehyde (MUF) resin have usually problems in formaldehyde emission and derived from petrochemical products, so developing green and environmentally friendly biomass-based wood adhesives has become a research topic of wide focus. As a biomaterial, cellulose (and its derivatives) is the largest bio-resource in the world, and developing its application in wood adhesives synthesis has outstanding raw material advantage. Therefore, in this study, a formaldehyde-free cellulose-based wood adhesive (OCHU) was prepared from carboxymethyl cellulose (CMC) by oxidizing with NaIO4 and then cross-linked with a laboratory synthetic polyurea compound (HU). The effect of oxidation time, oxidation temperature, NaIO4, and HU addition on the structures and properties of OCHU adhesive was investigated. The results showed that the adhesive OCHU prepared in 20 % (w/w based on CMC) of NaIO4 oxidized CMC at 50 °C for 8 h, and then polymerized with HU of equal mass to CMC presents excellent bonding performance. The dry strength, 24 h cold water and 3 h hot water (63 °C) soaking wet strength of its bonded plywood are as high as 1.98 MPa, 1.18 MPa, and 1.40 MPa, respectively, which conformed to the standard requirements in Chinese national standard GB/T 17657-2013. This work provides an effective scheme for preparing cellulose-based wood adhesives with high bonding strength, water resistance, and environmental friendliness. Thus this prepared OCHU adhesive has broad industrial application potential in preparing high-performance plywood.