Mesut Yalcin

Changes in the chemical structure and decay resistance of heat-treated narrow-leaved ash wood

We analyzed the effects of heat treatment on the chemical structure of wood from narrow-leafed Ash (Fraxinus angustifolia), a fast-growing and economically valuable species. We also analyzed the effects of heat treatment on the wood’s resistance to four decay fungi. Narrow-leafed Ash wood samples were heated with saturated steam to 140, 180, 200, and 220°C for 2, 4, and 6 h. The relative contents of extractable components were analyzed, as well as the levels of holocellulose, cellulose, and lignin. In addition, the density, equilibrium moisture content, and pH of the samples were measured. To determine the effects of heat treatment on resistance to decay fungi, the samples were exposed to the white rot fungus Trametes versicolor, dry rot fungus Serpula lacrymans, and the brown rot fungi Coniophora puteana and Gloeophyllum trabeum. Changes in the chemical composition of the wood due to heat treatment were correlated with increased resistance to fungal decay. While the hemicellulose content was dramatically reduced with increasing temperature and treatment duration, the lignin content increased proportionately. Thus, heat treatment is an environmentally friendly method of preserving narrow-leafed Ash wood against various decay fungi.

Determination of biological performance, dimensional stability, mechanical and thermal properties of wood–plastic composites produced from recycled chromated copper arsenate-treated wood:

The aim of this study was to investigate the dimensional stability, mechanical and biological performance and thermal degradation of wood–plastic composites made from high-density polyethylene and recycled wood treated with chromated copper arsenate (CCA), a commonly used wood preservative chemical. Virgin pine wood samples were also prepared with and without a coupling agent and used as the control group. Samples of CCA-treated Scots pine (Pinus sylvestris L.) with varying wood content were produced by adding different ratios of the coupling agent. The recycled CCA-treated wood-filled composites exhibited better flexural and tensile strength properties and dimensional stability than the control group, whilst their impact strength was less. Biological test values showed improved durability against termites and fungus with the recycled CCA-treated wood-filled composites. In addition, the leaching of heavy metals was significantly diminished when the coupling agent was utilized at a level of 5% (w/w), thus presenting a much lower impact on the environment.

ACTIVITY OF COMMERCIAL STILL WATERS FROM VOLATILE OILS PRODUCTION AGAINST WOOD DECAY FUNGI

The antifungal properties of some commercial plant waters obtained as side products in producing distilled oils were investigated. Paper disc samples were impregnated with various plant waters and exposed to wood decay fungi for 3 months in Petri dishes. Ten types of plant water (Laurus nobilis, Calluna vulgaris, Lavandula stoechas, Thymus vulgaris, Myrtus communis, Eucalyptus globulus, Mentha pulegium, Urtica dioica, Melissa officinalis, and Matricaria chamomilla were examined. Seven fungi were used (Phanerochaete chrysosporium, Ceriporiopsis subvermisphora, Gloeophyllum trabeum, Trametes versicolor, Oligoporus placenta, Pleurotus ostreatus, and Coniophora puteana). The antifungal activities of the plant waters obtained from thyme and lavender were particularly high.

LARVICIDAL ACTIVITIES OF SOME BARK AND WOOD EXTRACTS AGAINST WOOD-DAMAGING INSECTS

This study investigates the larvicidal activities of plant extracts and tannins against wood-damaging insects. Scots pine (Pinus sylvestris), beech (Fagus orientalis), and poplar wood (Populus tremula) were subjected to larvae of Spondylis buprestoides (Coleoptera: Cerambycidae) by impregnating them with mimosa (Acacia mollissima), quebracho (Schinopsis lorentzii) and redpine bark (Pinus brutia) extracts. At the end of the 6-month experiment, the numbers of dead and live larvae as well as the mean mass losses of woods were determined. In terms of wood species, the lowest larva resistance was observed in Scots pine wood, while the highest larva resistance was achieved by beech wood. The lowest mass losses and the highest dead termite rates in all tree species were observed when the concentration of mimosa and quebracho extracts was 12%. On the other hand, the pine bark extract showed a lower larvicide effect than the other two extracts.