Modifying Wood Surfaces with Atmospheric Diffuse Coplanar Surface Barrier Discharge Plasma

This study presents possibilities of influencing the surface properties of Sessile Oak (Quercus petraea), European Ash (Fraxinus Excelsior), Norway spruce (Picea Abies), and European Larch (Larix decidua) by a low-temperature atmospheric plasma treatment (diffuse coplanar surface barrier discharge [DCSBD]) in various conditions of the plasma treatment. Effect of mutual distance from the surface of the electrode to a plasma-treated wood surface (from 0-1.2 mm), effect of plasma treatment duration (3, 5, and 10 s) usable on industry lines as well as the effect of the atmosphere used during the plasma treatment (air, N2, and CO2) were studied. Effects of plasma treatment on the wood surface were evaluated by measurement of water droplet contact angle, which expressed changes in the surface polarity. Mutual distance from the surface of the DCSBD planar electrode to the surface of a treated wood sample plays a crucial role in the final change of the surface polarity. If the mutual distance is set in the range from 0 to 0.4 mm, the hydrophilization effect is reflected on the surface of treated wood. Increased polarity can be expressed by measuring the contact angle of water droplets. In this case, this is reflected by lower values of contact angles than those of the reference plasma-untreated wood samples. Conversely, by setting mutual distance within a range of 0.5-1.2 mm, the hydrophobization effect was observed, as demonstrated by the increase in the contact angle values of plasma-treated wood samples compared with the reference sample, which in this case was wood hydrophobization. Hygrophobization of the wood surface was unlike many other published experiments and was achieved without the addition of other specialty chemicals only by setting the appropriate mutual distance. Conditions for possible industrial use of the plasma modification for all tested wood samples were found