Possibilities for use of thermally modified poplar veneer were evaluated for the production of plywood boards in industrial conditions. Formats of poplar veneer were treated at temperatures of 190 °C, 200 °C, 210 °C, and 215 °C for 1 h. By combining the treated and non-treated formats of veneer, thirteen different types of board were made. Analyses showed that the examined physical and mechanical properties were influenced by both the type of construction and the applied thermal treatment. Boards composed only of thermally modified veneer achieved the best results regarding moisture absorption and dimensional stability, and boards composed of the combined veneers had better mechanical properties. Treatments at 200 °C and 210 °C proved to be optimal, while the treatment at 215 °C was too harsh and should not be used for the thermal modification of poplar veneer.
Nine-layer laminated veneer lumber (LVL) 1300 by 850 mm, in nominal thickness of 20 mm, was produced using beech veneer and reinforced LVL (RLVL), by inserting carbon fiber fabric between the veneer sheets. The research aimed to assess the enhancement of flexural properties, both in edgewise and flatwise bending, of beech LVL reinforced with carbon fiber fabric. Two types of reinforcements were made, using two types of adhesives: phenol-formaldehyde (PF) and polyurethane (PUR), in the industrial conditions. In the first group of samples (K1), the reinforcements were placed further from the neutral axis, and in the second group (K2) closer to the neutral axis. These groups were compared to the unreinforced control sample (K). Some physical properties, bending behavior parallel to the grain, and failure mode were determined and analyzed. Edgewise bending strength of the RLVL was about 11% higher than the control in the case of PF adhesive, while flatwise bending strength was about 40% lower than the control in the case of PUR adhesive. The experimental data were verified using the ANOVA model. The most important results of the study define different behavior and fracture mechanisms for each reinforcement and adhesive, highlighting the potential of RLVL for structural applications.