Dry Bond Strength and Water Resistance of Konjac Glucomannan, Chitosan, and Polyvinyl Alcohol Blend Adhesive

An environmentally-friendly wood adhesive was developed by blending konjac glucomannan (KGM), chitosan (CH), and polyvinyl alcohol (PVA) together. The viscosity of the KGM-CH-PVA (KCP) blend adhesive was determined, and the morphology of the film was observed using scanning electron microscopy (SEM). The KCP blend adhesive was applied to plywood during the manufacturing process, and the effects of the KGM, CH, and PVA contents on the bond strength was investigated. Results showed that KGM greatly increased the viscosity of the KCP blend adhesive, whereas the addition of PVA decreased the viscosity in the test range. The SEM observations showed that the KCP blend adhesive was homogeneous. The bond strength of the plywood that was treated with KCP blend adhesive increased with increasing KGM and CH concentrations, and desirable performance could be obtained with a total solids content of 4.6%. The KCP blend adhesive with 2.0% KGM, 2.0% CH, and 0.6% PVA exhibited a comparable bond strength with phenol formaldehyde. Findings suggest that the KCP blend adhesive can be used as a wood adhesive with all raw materials, having the advantage of being environmentally friendly