Development of an industrial applicable dielectric barrier discharge (DBD) plasma treatment for improving bondability of poplar veneer

Dielectric barrier discharge (DBD) plasma treatment in a larger scale, which has the potential for industrial application, was studied for modification of poplar veneer surface for enhancing its interface adhesion. Chemical property, morphology, surface wetting, adhesion property and the stability of the activation after plasma treatment were investigated. ESR, XPS, AFM, contact angle (CA), and shear strength test were carried out to evaluate the effect of plasma treatment. The following properties increased after treatment: the surface free radical concentration, O/C ratio, surface roughness of wood fiber, veneer surface wetting, and surface free energy. Consequently, the plywood composite prepared after plasma treatment showed higher adhesion strength than that prepared from untreated veneer. The best plywoods were obtained from veneers treated at processing power of 4.5 kW of DBD. The time-dependent analysis by surface wetting indicated a modified stability in the first two days after plasma treatment, after which the polar component of the surface decreased and its dispersive component kept the level observed after plasma treatment. In summary, veneer surface modification by DBD plasma is promising for industrial application.