Modifying Wood Surfaces with Atmospheric Diffuse Coplanar Surface Barrier Discharge Plasma (original) (raw)
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Holzforschung, 2020
Plasma treatment is becoming a mature technique for modification of surfaces of various materials, including wood. A better insight in the treatment process and the impact of the plasma on properties of wood bulk are still needed. The study was performed on Norway spruce and common beech wood, as well as their thermally modified variations. The formations of the airborne discharge, as well as mass changes of the treated wood, were monitored. The impact of such treatment on wood-coating interaction was investigated by evaluating the dynamic wettability and penetration into wood. At the wood surface, plasma streamers were observed more intense on denser latewood regions. Wood mass loss was higher with increasing number of passes through the plasma discharge and was lower for thermally modified wood than for unmodified wood. Plasma treatment increased the surface free energy of all wood species and lowered the contact angles of a waterborne coating, these together indicating enhanced wettability after treatment. Finally, the distribution and penetration depth of the coating were studied with X-ray microtomography. It was found that the coating penetrated deeper into beech than into spruce wood. However, the treatment with plasma increased the penetration of the coating only into spruce wood.
Modifying wood surfaces with diffuse coplanar barrier discharge plasma
Wood and fiber science: journal of the Society of Wood Science and Technology
This work 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 (DCSBD - Diffuse Coplanar Surface Barrier Discharge) in various conditions of the plasma treatment. Effect of mutual distance between surface of the electrode and plasma treated wood surface (from 0 to 1.2 mm), effect of plasma treatment duration (3, 5, 10 s) utilizable on indutry lines as well as the effect of the atmosphere used during the plasma treatment (air, N2, CO2) were studied. Effects of plasma treatment on the wood surface were evaluated by the measurement of water droplet contact angle, which expressed changes in the surface polarity. Mutual distance between surface of DCSBD planar electrode and surface of treated wood sample plays crucial role in the final change of the surface polarity. If the mutual distance is set in ...
In this work, surface activation of European beech wood (Fagussylvatica) treated by diffuse coplanar surface barrier discharge plasma (DCSBD) is presented. Plasma activation was performed in air atmosphere. The power of plasma in the treatment was 400 W and exposure times were of 3, 5 and 10 s. The wettability of wood was investigated through the measurement of water droplet contact angle. DCSBD plasma generates a wide range of reactive species in ambient air. These species react with the treated sample surface and provide a convenient resource for surface activation of wood material and its components. DCSBD plasma activation demonstrated that plasma treatment is an effective method for changing the wood surface wettability depending on the surface/electrode distance (from 0 to 1.6 mm). At a distance of up to 0.4 mm, the surface becomes hydrophilic when compared with the untreated sample. On the contrary, if the distance exceeds 0.8 mm, the surface becomes hydrophobic.The hydrophobic effect evolved during storage time.
Modification of wood by low-temperature atmospheric discharge plasma
Modification of wood by low-temperature atmospheric discharge plasma. Discharge plasma at atmospheric pressure was used to improve the wetting and adhesion properties of wood. Although also lowpressure plasma processes and namely atmospheric pressure processes are more attractive for wood industry applications because of their lower cost, higher throughput, and ability to operate in-line without vacuum systems. Atmospheric pressure plasma system is typically based on volume diffuse barrier discharge arrangement, where the treated material is placed between the discharge electrodes. However, using the sessile droplet technique, we have identified a significant increase of polar component of surface free energy. Polar part of surface free energy is associated with the presence of acid/base forces (electron donor-acceptor bonds). The treatment of wood exhibited a substantial aging effect; nevertheless the treated surface never recovers to its initial hydrophobic state. The enhancement of wood wettability is a necessary condition to promote a better adhesion with a water-based adhesives and coatings, which is currently being studied. The involvement of planar plasma source in our case makes the quality of the plasma treatment completely independent on the thickness and electrical conductivity of the wood material treated.
Modification of Wood by Atmospheric Discharge Plasma
2011
The atmospheric discharge plasma has been used to improve the wetting and adhesion properties of wood. The low-temperature plasma processes are attractive for wood industry applications because of their lower cost, and ability to operate in-line without vacuum systems. However, using the sessile droplet technique, we have identified a significant increase of polar component of surface free energy. Polar part of surface free energy is associated with the presence of acid/base forces (electron donor–acceptor bonds). The treatment of wood exhibited a substantial aging effect; nevertheless the treated surface never recovers to its initial hydrophobic state. The enhancement of wood wettability is a necessary condition to promote a better adhesion with a water-based adhesives and coatings, which is currently being studied.
Plasma Activation of Wood Surface by Diffuse Coplanar Surface Barrier Discharge
Plasma Chemistry and Plasma Processing, 2008
Radial cuts of Pedunculate oak (Quercus robur L.) heartwood was activated by Diffuse Coplanar Surface Barrier Discharge (DCSBD) plasma. The plasma treatment resulted in a considerable increase of free surface energy and in the substantial reduction of 50 ll water droplet uptake time. FTIR analysis confirmed the formation of additional polar functional groups on the wood surface due to the plasma treatment. This is consistent with the shift of wood surface pH level towards more acidic values. The energy efficiency of the DCSBD plasma treatment is better comparing to the known volume dielectric barrier discharge treatment method.
European Journal of Wood and Wood Products, 2013
Sample material from spruce (Picea abies), beech (Fagus sylvatica) and ash (Fraxinus excelsior) with radial and tangential section was treated by diffuse coplanar surface barrier discharge (DCSBD) plasma generated in air at atmospheric pressure. Plasma activated samples exhibited significantly lower water uptake times of 50 ll droplets and minimal differences in wetting between the two cutting planes (radial and tangential), when compared to the untreated surface. Simultaneously, more uniform spreading of the droplets and increased area of wetting on the activated surface were achieved. The plasma treatment had no effect on the water absorption coefficient of the wood samples. FTIR measurements confirmed the presence of oxygen containing functional groups and structural changes in lignin on the activated wood surface. The minimal heating of the treated samples suggests this method to be applicable to treat heat sensitive wooden materials.
Plasma Chemistry and Plasma Processing, 2010
Surface inactivation is a phenomenon that causes poor adhesion. A wood surface exposed to contaminants such as dust or atmospheric grime can experience surface inactivation. Inactivation mechanisms can reduce the attractive forces on the wood surface and lead to a decrease in wettability. Plasma treatment has been applied to recover inactivated wood surfaces for better adhesion and bonding. Plasma treatment technology is very simple and the cost is rather low. In addition, this treatment produces no environmental pollution. In this study, low pressure plasma treatment was applied to reactivate the surfaces of spruce wood for glue bonding and to increase wettability after a 9-year period of natural surface inactivation. Changes in contact angles, surface energy, surface colour and bonding strength of inactivated and oxygen plasma treated wood surfaces were studied. Wettability, bonding and other mechanical strength properties of plywood panels increased with the oxygen plasma treatment.
Pre-treatment of beech wood by cold plasma
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology, 2013
Pre-treatment of beech wood by cold plasma. Adhesive joints of wood could be strengthened by plasma treatment of the surface. The low-temperature discharge plasma has been used to improve the wetting and adhesion properties of wood. The contact angle of water drop showed a steep decrease after activation by RF plasma in air and the surface energy and its polar component of beech wood were increased with time of plasma activation.