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.
Composite wood products
Saeid Ismaeilimoghadam; Afsaneh Shahraki; Fatemeh Dehdast; Samaneh Pourkarami
Abstract
The objective of this study was the evaluation of the addition of silica particles in composite on natural resistance and morphology of wood plastic composite against of white rot fungi (Trametes Versicolor). Wood flour at the ratio of 60% (w/w), polypropylene and 2 per hundred compound (phc) MAPP was ...
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The objective of this study was the evaluation of the addition of silica particles in composite on natural resistance and morphology of wood plastic composite against of white rot fungi (Trametes Versicolor). Wood flour at the ratio of 60% (w/w), polypropylene and 2 per hundred compound (phc) MAPP was mixed. Nano and micro silica at 0, 1, 3 and 5 (phc) were added as filler. The mixing process in internal mixer (HAAKE) was done and test specimens were prepared using injection molding. The test specimens were exposed to Trametes Versicolor fungi for 8, 12 and 16 weeks at 25 oC and 75% humidity according to BS 838:1961. Then the mass loss, long-term water absorption and humidity coefficient diffusion of the samples were measured. The formation of hydrogen bonds between silica and wood flour was determined by Fourier Transform Infrared (FTIR) spectroscopy and the morphology of composite was stydied using scanning electron microscopy (SEM). The result showed that with increasing period of samples exposure to fungi, the mass loss, long-term water absorption and humidity coefficient diffusion in wood plastic composite increased. However at higher silica, decay in the samples was decreased. The effect of silica nanoparticles on natural resistance of wood plastic composite was higher than sample containing silica micro particles. Infrared spectroscopy showed hydrogen bonds between wood flour and silica. The result of scanning electron microscopy showed that with increasing of exposure time to fungi, small and large cracks in composite were created. However increasing silica addition, these cracks were decreased.
Management and Economics wood
Aliakbar Aenayati; Hamid Hatefnia
Abstract
Microbiological degradation of wood and wood products is one of the most important of disadvantage which reduce its useful life. There are various methods to increase the natural durability of wood and wood products and most of them using chemical reagents. In the past, the thermal ...
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Microbiological degradation of wood and wood products is one of the most important of disadvantage which reduce its useful life. There are various methods to increase the natural durability of wood and wood products and most of them using chemical reagents. In the past, the thermal modification has been used as a ecofriendly method in many times. In this research the effects of steam pretreatment on the fungal durability of particleboard were studied. Steam pre-treatment was applied on the poplar wood particles using a stainless steel reactor at four temperature levels (155, 165, 175 and 185 ºc) and three retention times (15, 30 and 45 min). The amount of hemicelluloses, acetone extractives of wood particles as well as EMC and Mass loss of test panels were measured.The results indicated that the steam pretreatment significantly decreased the amount of hemicelluloses of wood particles, EMC and mass loss of test samples where as the amount of extractives of wood particles increased.According to the results, the variation of Mass loss of particleboard test samples showed a significant correlation to the variation of EMC of test samples, hemicelluloses and extractives amount of wood particles when the wood particles thermally pre-treated at 165ºC for 30 minutes
Management and Economics wood
Arash Hassan poor; Behzad Bazyar; Habib alah Khademi eslam; Amir Hooman Hamasi
Abstract
Wood polymer composites (wpc) have been extracting used for building Products, Automotive, Packaging materials and another applications. Wpc is subject to fungal attack due to wood components. Early detection of wood decay is critical because decay fungi can cause mass loss and rapid structure failure. ...
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Wood polymer composites (wpc) have been extracting used for building Products, Automotive, Packaging materials and another applications. Wpc is subject to fungal attack due to wood components. Early detection of wood decay is critical because decay fungi can cause mass loss and rapid structure failure. The objective of this study was to compare the effects of two fungi Trametes versicolorand Coniophora puteana on the mass loss of wood plastic composites. Specimens as four various treatments: contain 40,50,60,70 percent of wood flour in composition, were exposed to brown rot and white rot for 4, 8, 12, 16 week. After each of mentioned time Mass loss was measured and its amount increased for each of treatments. As seen, most amount of mass loss occurred on 16th week after contamination and in samples with 70% wood flour about two fungi .Results shown that contamination time and wood flour percent in composition have direct correlation with composites mass loss. Also at same treatments and contamination times white rot has more severe effects on mass loss factor than brown rot.
