Effect of plasma treatment on the surface characteristics and adhesive penetration performance of heat-treated wood

Abstract

Abstract The present study used an atmospheric dielectric barrier discharge (DBD) plasma treatment to modify the interfacial properties of heat-treated wood (HTW). The changes in the wood surface characteristics, such as the microstructure, chemical structure, and wettability, were investigated using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), Fourier-transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Further, the fluorescent tracer technique was used to analyze the effect of plasma treatment on the adhesive penetration inwood. Results showed that the wettability of water and phenol-formaldehyde adhesives on the surface of HTW significantly improved after plasma treatment due to the increase in the hydrophilic and oxygen-containing functional groups. The average penetration (AP) and effective penetration (EP) of the phenolic adhesive into HTW also increased significantly after plasma treatment; the AP value of the E-E (earlywood bound to earlywood) HTW samples increased from 909 to 1674 μm, and the EP value from 60 to 183 μm upon plasma treatment. These observations indicate that the DBD plasma treatment is a promising method to improve the bonding properties of the glued HTW products.