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Hybrid LVL panels made of eucalypt and pine woods decayed by white-rot fungus

Delucis R., Herrera R., Melo R., Muller M., Labidi J., Gatto D.

Drewno : prace naukowe, doniesienia, komunikaty

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2018

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vol. 61, nr 201

165--176

EN

LVL panels have been employed for structural purposes on a large scale, replacing not only solid wood, but also other materials, due to their high mechanical properties combined with an ecological appeal. This study aimed to investigate the degradation which occurred in hybrid LVL panels composed of pine and eucalypts woods from fast-growing plantations, layered as six different combinations of five veneers. In order to evaluate the behaviour of the panels underwater immersion, some samples were subjected to an ageing process performed prior to mycological tests. For characterization, mass loss, colourimetric properties (CIELAB method) and Janka Hardness were the used parameters. The results indicated that the panels made with adjacent eucalypts veneers were more susceptible to water immersion. The panels made with pine veneers as cores showed lower hardness. The hybrid panels combined high durability and good water resistance.

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Chemical composition and inhibitory effects of Vectandra grandiflora leaves essential oil against wood decay fungi

Silva D. T., Bianchini N. H., Muniz M. F. B., Heinzmann B. M., Labidi J.

Drewno : prace naukowe, doniesienia, komunikaty

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2016

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vol. 59, nr 197

189--198

EN

The environmental toxicity and potential human health problems that can be caused by most common wood preservatives are pushing forward the search of safe preservatives from renewable resources. Consequently, several studies have been realized to assess the potential of plant extracts in terms of fungal resistance for wood products. In this context, the present work aims to evaluate the inhibitory effects of essential oil obtained from the leaves of Nectandra grandiflora against wood decay fungi. Chemical characterization was carried out by gas chromatography and the antifungal activity was performed by the radial growth technique. Firstly, the potato sucrose agar medium was supplemented with essential oil at concentrations ranging from 0 (control) to 5.0 μL·mL-1. Afterwards, mycelial discs of Pycnoporus sanguineus and Gloeophyllum trabeum were transferred to the plates and the results were evaluated by the probit method. Chemical analysis revealed a complex mixture of sesquiterpenoids in the essential oil, which presented dehydrofukinone as a major compound. The essential oil and dehydrofukinone proved to be effective in the mycelial growth control of G. trabeum and P. sanguineus. These preliminary reports demonstrated the suitability of the N. grandiflora essential oil as a component of preservative solutions.

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Characterization of thermally modified wood at different industrial conditions

Herrera R., Krystofiak T., Labidi J., Llano-Ponte R.

Drewno : prace naukowe, doniesienia, komunikaty

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2016

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vol. 59, nr 197

151--164

EN

In this study European ash wood (Fraxinus excelsior L.) was modified at 192ºC and 202ºC in Thermo-Drewno®, Poland; and at 212ºC in Termogenik®, Spain. After modification, samples were characterized by wet chemistry according to standard methods (TAPPI) and by instrumental methods (FT-IR); in addition, surface and physical properties were measured (density, acidity, moisture, water uptake, contact angle, colour) in order to quantify changes due to treatment and temperature. The results showed that chemical composition of modified wood presents a gradual variation according to the heating regime, regardless of the industrial process applied; the greatest differences were obtained in treatment at 212°C compared to untreated wood. Furthermore, the density (< 0.68 g·cm-3) of modified wood decreased proportionally to treatment temperature. Colour measurements showed proportional changes to darker colours depending on the treatment temperature. On the other hand, some physical properties did not vary significantly between treatments, obtaining similar values of contact angle (97°-99°) and of moisture content (<7%).