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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.

Due to the significant and harmful effect of the global warming on our communities, health, and climate, the usage of thermal insulation material in building is must to decrease the energy consumption and to improve energy efficiency. On the other hand, the utilization of waste and biomass resources for developing new bio-based composite materials is attracting much attention for the environmental and socioeconomics. Therefore, in this study, thermal insulation bio-based composite panels from Tetra Pak® waste and wool fiber waste with different ratios were manufactured. Likewise, other sandwich bio-based composite panels were manufactured using Tetra Pak waste as a core material with glass woven fabric and jute wove fabric as skin materials. Thermal conductivity and thermal resistance results showed a significant improvement on thermal insulation properties of the developed biocomposite panels compared to the control samples made of plain Tetra Pak®.

Aim of study: Formaldehyde content of most of resins used in wood based composite production, wood composite materials have been seen a threat on human health and environment. Therefore, numerous studies have been made to develop an effective method to decrease formaldehyde emission from the wood based panels and various methods have been tried. The aim of the study was to investigate those effects of press parameters on some technological properties of polystren composite plywood.

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An ideal veneer surface is crucial for good panel properties in plywood manufacturing. The aim of this study was to compare plasma treatments and sanding (mechanical) processes with respect to the surface roughness of veneers. Rotary-cut veneers with a thickness of 2 mm from Scots pine (Pinus sylvestris) logs were used as material. After rotary peeling, veneer sheets were dried at 110 °C in a veneer dryer. Veneer sheets were divided into 4 main groups. The surfaces of the control veneer sheets were left untreated. Two different grits of sandpaper, 80 and 180, were used for sanding the surfaces of veneers. Plasma treatment was applied to the last veneer group with 3 different gases (oxygen, nitrogen, and ammonia) and 3 different plasma times (1 min, 5 min, and 15 min). The Mitutoyo Surftest SJ-301 instrument was used to determine surface roughness of samples. Average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Rmax) parameters were measured to evaluate the surface roughness of the samples based on DIN 4768. It was found that the smoothest veneer surfaces were obtained with the sanding processes. Surface roughness values (Rz) of veneer sheets sanded with 180 grit sandpaper were lower than those of veneers sanded with 80 grit sandpaper. Compared with the plasma treatment in terms of surface roughness, plasma-treated veneers had higher Rz values. It was also determined that Rz values were the lowest in the veneers treated with nitrogen plasma. Additionally, the surface roughness values of Scots pine veneers treated with ammonia plasma were a little higher than those of veneer sheets treated with oxygen plasma. The effect of plasma treatment time on surface roughness was not found to be statistically significant.