Easy Preparation, High Water Resistance Glucose-Based Environment-Friendly Wood Adhesives

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Recently, formaldehyde-free environment-friendly bio-based wood adhesives have been a hot research topic in the wood industry. Glucose is a widely sourced biomass material, presenting also good reactivity, which has made it a focus of cutting-edge research. In the work presented here, a new formulation was developed for preparing a glucose-based biomass adhesive with excellent bonding strength and water resistance. Glucose was oxidized by sodium periodate at room temperature to generate bioaldehydes (OG), which were then reacted with a polyurea (HU) synthesized by reaction of hexamethylene diamine (HMD) with urea (U) via deamination. This resulted in an environmentally friendly green glucose-based adhesive (OGHU resin) containing neither formaldehyde nor other toxic volatile aldehydes. The effect of the mass ratio of HU/OG on the resin properties was investigated. The results showed that the OGHU resin imparted to the plywood bonded with excellent bonding strength and water resistance. The dry shear strength, 24 h cold water soaking wet strength, 3 h hot water (63 °C) wet strength, and 3 h boiling water wet strength were as high as 1.48 1.16, 1.26, and 1.12 MPa, respectively. Its superior bonding performance exceeded the expectations of the GB/T 9846–2015 standard (≥0.7 MPa) sufficiently to be considered as a substitute for the currently used urea-formaldehyde wood panel adhesives.