Bending properties of wood after its decay with Coniophora puteana and subsequent modification with selected chemicals

IRG/WP 99-40146

L Reinprecht, S Varinska

Mechanical properties of wood are often decreased due to decay processes caused by biotic and/or abiotic factors. Damaged wooden elements (e.g. historical structures) can be reinforced by more methods, including their modification with convenient chemicals. This paper presents influences of selected chemicals on basic bending properties (modulus of elasticity - MOE, modulus of rupture - MOR) of sound and decayed wood. Norway spruce (Picea abies L. Karst.) and European beech (Fagus sylvatica L.) samples 8.5 x 8.5 x 120 mm (RxTxL) were deteriorated with the brown-rot fungus Coniophora puteana in laboratory conditions in the interval from 2 to 10 weeks. These rot samples as well as the sound ones were subsequently modified with 5 different chemicals (shellac, epoxy resin, melamineformaldehyde resin, polybutylmethacrylate, or polyethyleneglycol) using pressure impregnation technique (p = 0.8 MPa, t = 6 h). The MOE were evaluated continually for each sample in its sound, rot and modified state (or in sound and modified state), while the MOR just for groups of sound and modified samples. An apparently positive effect on the MOE was achieved with the melamineformaldehyde and epoxy resins, while the polybutylmethacrylate and shellac had only a gentle positive effect. The MOR was increased mainly with the epoxy resin. On the other hand, the polyethyleneglycol - PEG 1000 had an apparently negative effect on both bending properties.


Keywords: NORWAY SPRUCE; EUROPEAN BEECH; ROT; CONIOPHORA PUTEANA; MODIFICATION; SHELLAC; EPOXY RESIN; MELAMINEFORMALDEHYDE RESIN; POLYBUTYLMETACRYLATE; POLYETHYLENEGLYCOL; MODULUS OF ELASTICITY; MODULUS OF RUPTURE

Conference: 99-06-06/11 Rosenheim, Germany


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