Influence of Atmospheric Pressure Dielectric Barrier Discharge Plasma Treatment on the Surface Properties of Wheat Straw

The effects of atmospheric pressure dielectric barrier discharge (DBD) plasma on the surface properties of wheat straw were investigated in this work. The surface wettability changes in the wheat straw were determined using contact angle measurements, the surface morphology was observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the chemical characteristics were scanned using X-ray photoelectron spectroscopy (XPS). Moreover, the shear strength was measured using a paper tension meter. The results indicated that after plasma treatment, the urea-formaldehyde (UF) resin had lower instantaneous and equilibrium contact angles on the wheat straw surfaces than the untreated specimens did, which decreased by 34% and 64%, respectively. Obvious etching was observed on the wheat straw surface after plasma treatment. There was an increase in the O/C ratio along with an increase in the C2, C3, and C4 proportions based on the XPS analysis after plasma treatment on wheat straw surface. Moreover, the shear strength between glued surfaces of the wheat straw was greatly improved after plasma treatment, indicating that atmospheric pressure DBD plasma treatment was an effective method for improving the surface properties of wheat straw, which were helpful for UF resin penetration and application of wheat straw.