Fungal decay and bending properties of beech plywood overlaid with tropical veneers
2012
Kmetová, l. | Reinprecht, l. | Iždinský, J.
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 (Entandrophragmasp.) 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 veneeringwere performed by hot pressing process using waterproof phenol-formaldehyde resin in order to producepanels suitable to be used in exterior exposure without ground contact, i.e. in use class 3. Durability of theveneered plywood was assessed by their exposure to two brown-rot fungi (Serpula lacrymansandConiophoraputeana) and two white-rot fungi (Phanerochaete chrysosporiumandTrametes versicolor) for 16 weeks accordingto the modified EN 113 using edge protected specimens. Beech plywood overlaid with padouk veneers hadthe lowest mass loss after fungal attack. However, good antifungal effects were also accomplished usingthe iroko, bubinga and wengé veneers. Bending characteristics (MOR, MOE) of the veneered plywoodboards were partly influenced by the type of surface veneers, with the lowest values for iroko veneers andthe highest values for wengé.
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