Wooden composites from beech plywood and decorative veneers of different natural durability - their decay resistance and selected physico-mechanical properties

This work deals with decay resistance and selected physical and mechanical properties of wooden composites (WCs) prepared from 3.6 mm thick three-layer beech plywood and 0.6 mm thick decorative surface veneers of selected exotic (aningr´e, bubinga, iroko, khaya, padouk, sapelli, weng´e) and domestic (beech, European oak, sweet chestnut, walnut) wood species. Joining of veneers in the plywood and then also in the WCs was carried out by pressing processes using the PF glue Fenokol 43. The aim of the experiment was to determine the influence of surface veneers of different natural durability on rotting of the WCs, and on resistance of the WCs to water and mechanical loadings, as well. Decay resistance of individual veneers and WCs was tested by modified EN 113 against the brown-rot fungi Serpula lacrymans or Coniophora puteana, and the white-rot fungi Phanerochaete chrysosporium or Trametes versicolor. Weight losses of individual types of veneers and WCs caused by wood-destroying fungi were compared with weight losses of beech-veneer and beech-WC, respectively. The lowest weight losses at rotting processes showed the padouk-WC, i.e. WC prepared from the beech plywood and two the most durable padouk surface veneers. Density, water soaking, water swelling, tensile strength perpendicularly to the plane (?), and bending characteristics (MOR, MOE) of all WCs were determined in accordance with European standards. These physical and mechanical properties of the WCs were only partly influenced by the type of surface veneers. Selected types of the WCs, e.g. padouk-WC, could also be convenient for exterior expositions out of ground contact.