Title : Gluability of the thermally modified aspen, birch, and poplar rotary cut veneers with suberinic acids adhesive
Abstract:
The eco-friendly lifestyle has gained significant attention at both individual and industrial levels, leading up to Europe’s “Green Deal.” Progress has been made towards waste-free production methods in the woodworking industry, including in Latvia. However, wood processing still generates by-products that require effective utilization. While burning these residues for heat and electricity is a common approach, a more sustainable alternative is repurposing them by converting birch bark residues into suberinic acids adhesive. This material is not only environmentally friendly but also safe for human use. Thermal modification is another eco-friendly method that changes the chemical composition and properties of timber, helping to prolong the life cycle of the finished material. Preliminary research suggests that thermally modified veneers of aspen, birch, and poplar (treated at temperatures and durations such as 160 °C for 50 minutes, 204 °C for 120 minutes, 214 °C for 120 minutes, 217 °C for 180 minutes, and 218 °C for 30 minutes) using the ThermoVuoto process can be bonded with the suberinic acids adhesive under specific conditions (215 °C, 1.4 MPa pressure, and a pressing time of 5 minutes). These bonded veneers meet the EN 314-2:1993 standard requirements, making them suitable for outdoor applications classified as bonding Class 3, such as uncovered wooden structures. This demonstrates a practical and sustainable use of industrial by-products. Conversely, hydrothermally modified veneers treated under certain conditions (160 °C for 50 minutes) could not be successfully bonded using the same parameters, and their compliance with bonding Class 3 requirements could not be confirmed. It is likely that the surface roughness of the veneers after thermal modification, rather than just their density, mainly influences this outcome.
Funding: This research was conducted within the Latvian State research program project No. VPP-ZM-VRIIILA-2024/2-0002 “Innovation in Forest Management and Value Chain for Latvia's Growth: New Forest Services, Products and Technologies (Forest4LV)”.
