Effects of epoxy resin doping on properties of geopolymer wood adhesive

Objective In order to solve the problems of poor interfacial compatibility of geopolymer wood adhesive, epoxy resin was used as an organic dopant to construct organic-inorganic crosslinking network, so as to improve the comprehensive performance of epoxy resin doping on geopolymer wood adhesive.

Method Geopolymer-based wood adhesive was prepared by blending geopolymer with epoxy resin, polyether amine, and silane coupling agent KH550. The effects of different organic dopants on performance of the adhesive were analyzed, and the mechanism of organic dopants was analyzed by combining FTIR, XPS, SEM-EDS, and conical calorimeter.

Result Different organic doping improved the viscosity of geopolymer slurry. Given the mass fraction of epoxy resin of 4.8% and polyether amine of 1.2% (GECS₆), the viscosity of geopolymer slurry was lower, which was conducive to the uniform application of adhesive. Different doping substances improved the bond strength of geopolymer-based plywood to varying degrees. The wet bond strength of GECS₆ reached a better value of 0.87 MPa, which was higher than that of pure geopolymer adhesive by 248%. Compared with pure geopolymer adhesive, the heat release rate and total heat release of the organically doped geopolymer plywood decreased by 7.01% and 17.95%, respectively, and the fire resistance properties were improved to a certain extent.

Conclusion The synergistic effect of epoxy resin and silane coupling agent constructs an organic-inorganic crosslinking network, which can improve the compatibility between geopolymer adhesive and wood, improve the densification of paste, and solve the problem of poor interfacial compatibility of geopolymer wood adhesive, thus enhance bond strength and fire resistance of plywoods.