Wood Modification and Wood Preservation
Atiye Sadat Mousavi-Sangdehi; Reza Oladi; Davood Efhamisisi; Maliheh Akhtari
Abstract
Biological protection is one of the rather new and environmentally friendly methods of wood protection, in which living microorganisms have replaced chemical substances. This research was carried out with the aim of investigating the biological protection of beech wood against the white rot fungus (Trametes ...
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Biological protection is one of the rather new and environmentally friendly methods of wood protection, in which living microorganisms have replaced chemical substances. This research was carried out with the aim of investigating the biological protection of beech wood against the white rot fungus (Trametes versicolor) using Trichoderma harzianum. For this purpose, the antagonistic ability of Trichoderma against wood rotting fungus was evaluated in dual culture medium as well as on wood. Trichoderma was incubated on wood samples in two time periods of four and eight weeks, and then samples were exposed to white rot for 16 weeks. The dual culture test proved the antagonism of Trichoderma against wood-destroying fungi, in a way that after 14 days, Trichoderma had not only prevented the spread of T. versicolor hyphae, but also overgrew on its mycelia. Cellulase enzyme assay showed that this isolate of Trichoderma had little ability to secrete this enzyme, and for that reason, sample weight loss due to fungal treatment was neglectable; a result that was also confirmed by infrared spectroscopy. The duration of wood incubation with Trichoderma was an important factor in the efficiency of treatment: increasing the time by one month significantly reduced weight loss of treated samples from 15% to below 1%, while the weight loss of the control samples was more than 30%. It can be concluded that the long-term treatment of beech wood with Trichoderma does not have a destructive effect on the wood and protects it against the white rot. Therefore, it is suggested to use this type of biological agent as a pretreatment of beech wood or to combine it with other preservative materials.
Management and Economics wood
Neda Esmaeili; Maryam Ghorbani; Porya Biparva
Abstract
In this study, the mechanical and biological properties of modified poplar wood with glutaraldehyde and paraffin were investigated. Modification was performed with glutaraldehyde at different concentrations of glutaraldehyde, 5, 10 and 20% using magnesium chloride as a catalyst and then subsequently ...
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In this study, the mechanical and biological properties of modified poplar wood with glutaraldehyde and paraffin were investigated. Modification was performed with glutaraldehyde at different concentrations of glutaraldehyde, 5, 10 and 20% using magnesium chloride as a catalyst and then subsequently with paraffin by vacuum-pressure method. Increasing concentration of glutaraldehyde caused to weight gain and bulking wood cell wall, subsequently reduced paraffin penetration into the porous structure of wood. Biological resistance exposed to white rot fungi and mechanical properties were measured according to the standards EN113 and ASTM D143-94, respectively. Scanning electron microscopic images showed bulking of cell walls and paraffin presence in cell cavities. According to results of TGA, increasing of modification intensity decreased mass loss due to cross linking formation between glutaraldehyde and cell wall polymers. Paraffin at combined modification containing 10% and 20% glutaraldehyde improved significantly the modulus of elasticity. Glutaraldehyde reduced bending strength, but paraffin present in the modified samples improved it. The Glutaraldehyde increased compression strength parallel to grain and hardness that the improvement was more obvious in combined modification. Modification with glutaraldehyde enhanced decay resistance exposed to white rot fungi, and this improvement intensified at the presence of paraffin. Inhibitory influence of chemical modification on wood attacking white rot fungi can be attributed to decreases the wood moisture, bulking of cell walls and blocking cell cavities.
