FUNGAL DECAY AND BENDING PROPERTIES OF BEECH PLYWOOD OVERLAID WITH TROPICAL VENEERS

Abstract

REINPRECHT L, KMEŤOVÁ L & IŽDINSKÝ J. 2012. Fungal decay and bending properties of beech plywood overlaid with tropical veneers. Both surfaces of three-layer beech plywood were separately overlaid with thin veneers of seven tropical species: aningré (Aningeria robusta), bubinga (Guibourtia demeusei), iroko (Milicia sp.), khaya (Khaya ivorensis), padouk (Pterocarpus sp.), sapelli (Entandrophragma sp.) and wengé (Millettia laurentii), and one domestic species: beech (Fagus sylvatica), in order to assess their influence on the natural durability of the final panels against basidiomycetes. Laboratory preparation of beech plywood and its veneering were performed by hot pressing process using waterproof phenol-formaldehyde resin in order to produce panels suitable to be used in exterior exposure without ground contact, i.e. in use class 3. Durability of the veneered plywood was assessed by their exposure to two brown-rot fungi (Serpula lacrymans and Coniophora puteana) and two white-rot fungi (Phanerochaete chrysosporium and Trametes versicolor) for 16 weeks according to the modified EN 113 using edge protected specimens. Beech plywood overlaid with padouk veneers had the lowest mass loss after fungal attack. However, good antifungal effects were also accomplished using the iroko, bubinga and wengé veneers. Bending characteristics (MOR, MOE) of the veneered plywood boards were partly influenced by the type of surface veneers, with the lowest values for iroko veneers and the highest values for wengé.