Chitosan-Based Adhesive for Fabrication of Organic–Inorganic Hybrid Wood Composites with Robust Interfacial Bonding and Flame Retardancy

Abstract

High Resolution Image Download MS PowerPoint Slide In this study, a flame-retardant functional wood composite based on interfacial engineering enhancement was developed to address the demand for fire protection in buildings and the problems of traditional wood composites, such as flammability and formaldehyde release from adhesives. A chitosan-based adhesive (CPG) with strong bonding and flame retardant properties was prepared by physical-chemical synergistic cross-linking of phytic acid-solubilized chitosan (CS), glycerol triglycidyl ether (GTE), and in situ polymerized polyacrylamide to form an interpenetrating entanglement structure. Meanwhile, the wood substrate was modified by impregnating sodium silicate (SS) and aluminum hydroxide (AH) as flame retardants, and then the wood surface was grafted by using APTES to provide the reaction site between the adhesive and the wood substrate. The CPG adhesive showed superior cohesive strength and water resistance by forming an interpenetrating three-dimensional network structure and a wood bonding interface. The dry strength of plywood was 2.62 MPa, which was maintained at 1.42 MPa after the “4 + 4 + 1” harsh test (the plywood immersed in boiling water for 4 h, then dried at 63 ± 3 °C for 16 h, then immersed in boiling water for another 4 h, then immersed in 20 ± 3 °C water for 1 h). The flame retardant performance test shows that the limiting oxygen index (LOI) of the composite material has been improved from 25.3% to 60.1%, and the composite material has passed the UL-94 flame test to reach V-0 level, the peak heat release rate (pHRR) has been reduced by 53.1%, and the total smoke production (TSP) has been reduced by 87.4%. This study provides a new strategy for the development of environmentally friendly, high-bonding strength, and flame-retardant wood composites.

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