Bonding processes play a significant role in the wood and furniture industry. They allow for the creation of fixed joining of construction elements, creation of new materials and, last but not least, aesthetic appreciation of parts. However, the quality of bonded joints is affected by many factors, one of which is the moisture of the bonded materialwood. The main objective of this research was to determine the influence of wood moisture on the strength of bonded joints formed by polyvinyl acetate (PVAc) and polyurethane (PUR) adhesives. In current practice these adhesives are being increasingly used for their properties and zero formaldehyde content. The procedure for determining the bond strength (tensile shear strength of lap joints) corresponded to standard EN 205. It was ascertained that in addition to actual moisture of bonded wood, the quality of the joint is also affected by the environment to which the glued joint is subsequently subjected. In a normal environment, the strength of the tested joint PVAc adhesive decreases with increasing wood moisture, but it still meets the requirement of the standard. In a humid environment, the strength falls below the limit of the standardized value. In a normal environment the joint strength bonded with PUR adhesive is similar, but the decrease in strength is lower. In a humid environment it shows the highest strength at 20% wood moisture and meets the specified standard minimum strength (4 MPa). Graphs were created from the measured values that clearly show the influence of wood moisture on the final bond strength of a joint.

• This article is focused on evaluating the differences between the upper and lower faces of OSB/3 -Superfi nish in the course

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The purpose of this study was to evaluate the impact of glue line thickness on joint strength properties while using two types of PVAc adhesive (i.e., one-component Rhenocell 3W, 4B Plus, resistivity class D3, and two-component Protovil VP244/2C, resistivity class D4) belonging to the group of thermoplastic adhesives intended for nonconstruction joints. Joint strength testing was carried out using the transverse tensile test for estimation of the joint strength method. It was proven that if specimens were conditioned for 7 days at 20°C ± 2°C and a relative air humidity of 65 ± 5 percent, when testing one-component Rhenocell 3W, 4B Plus (D3) adhesive, increasing thickness of the glue line results in falling strength of the bonded joint. When testing the two-component Protovil VP244/2C (D4) adhesive, increasing thickness of the glue line always results in increasing joint strength, even under conditions when water is directly affecting the joint or under increased temperatures.

The objective of this study was to determine a correlation between the dynamic modulus of elasticity (MOEd) and the static modulus of elasticity (MOEs), and to assess the potential of using nondestructive (NDT) methods as a grading tool for both treated and untreated wood exposed to weathering. In the experiment, test samples made from spruce and oak were exposed for four months to natural weathering. Half of the specimens were treated with a silicon-based nano-protection. The MOEd was determined using acoustic NDT methods-ultrasound transmission (MOEdu) and the vibration methods (MOEdv), while the MOEs was determined by a destructive three-point bending test. The results showed that there was no statistical significance for the influence of the time of exposure and the surface treatment on the modulus of elasticity. The ultrasound method, measured in the longest distance of the sample, had the most significant correlation with the MOEs. The vibration method also reached a similar correlation with the MOEs. The mean values of the MOEdu and MOEdv were higher than the MOEs. The influence of density on the acoustic wave velocity was not confirmed.