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The surface properties of wood particles are one of the key factors for the development of mechanical and physical properties of particleboards. Particles were treated with plasma at atmospheric pressure with ambient air in order to enhance the polarity of wooden surfaces. One-layer particle boards were produced from the plasma-treated particles by using 3, 5, and 8 % urea formaldehyde adhesive (related to the particles). For all adhesive ratios, internal bond strength was increased by approximately 0.1 MPa compared to the respective controls. The modulus of rupture, modulus of elasticity and water related properties were only improved compared to the respective controls at the lowest adhesive content. It is therefore concluded that the plasma treatment can improve the bonding quality and water related properties of particleboards particularly at low adhesive contents

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In order to provide a database which documents the influence of plasma treatment on water uptake of wood veneers, veneers of 27 wood species underwent immersion tests in untreated and plasma-treated states. Plasma treatment was executed using an air driven dielectric barrier discharge at atmospheric pressure. The results showed that plasma treatment led to significantly improved water uptake for most of the wood species, but some wood species remained unaffected after plasma treatment

This study investigates the dimensional stability and mechanical properties of plywood boards made of thermally modified and unmodified beech veneers that have undergone plasma pre-treatment before melamine resin impregnation. The water and melamine resin uptake and resulting weight percent gain of the veneers were investigated, whereby the air plasma pre-treated veneers showed improved liquid uptake. Five-layer plywood boards were then manufactured and tested for their dimensional stability, compressive strength, bending strength, and tensile strength. Plywood boards made of thermally modified and plasma pre-treated veneers showed a significantly improved dimensional stability, along with small influences on their mechanical properties.

This study investigated the effect of a plasma treatment at atmospheric pressure on the absorption characteristics of beech veneers by using a dielectric barrier discharge on the DMDHEU (1,3-dimethylol-4,5-dihydroxyethylene urea). Immersion tests with varying immersion durations showed that plasma treatment significantly accelerated the DMDHEU-solution uptake of the veneers. Additionally, improved bulking characteristics were observed for plasma-treated and DMDHEU-immersed veneers

Thermally modified and unmodified beech veneers in untreated and plasma-treated state were immersed in melamine solution at different concentrations. The plasma pre-treated veneers exhibited significantly higher melamine loads than the untreated veneers at equal impregnation duration. Subsequently the veneers were manufactured into 5-layer plywood boards; the plywood samples then underwent an extreme testing procedure based on DIN-EN 314-1/2 in order to proof the bonding quality by means of shear strength. The plywood boards made of plasma pre-treated veneers exhibited up to 2.7-fold improvement in shear strength compared to plywood made of untreated veneers. Results differed markedly based on material (unmodified/thermally modified veneer) and concentration of melamine solution

This study addresses the question of whether the extractives or the main components of wood are responsible for the alterations in surface energy after air-plasma treatment. For this purpose, x-ray photoelectron spectroscopy was carried out on untreated, microtomed and air-plasma-modified beech wood surfaces. A dielectric barrier discharge at atmospheric pressure was used for plasma modification. The results indicate that air-plasma treatment affects the O/C-ratio and surface energy characteristics of wood surfaces by oxidative alteration and exposition of the wood main components