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Popescu C.-M.,Romanian Academy P Poni Institute Of Macromolecular Chemical | Manoliu A.,Romanian Institute of Biological Research | Lisa G.,Technical University Gheorghe Asachi | Gradinariu P.,Romanian Institute of Biological Research | Vasile C.,Romanian Academy P Poni Institute Of Macromolecular Chemical
Carbohydrate Research | Year: 2010

The effects of the soft-rot fungus Trichoderma viride Pers., on the thermal behavior of lime wood (Tillia cordata Mill.) were investigated. The lime wood pieces were inoculated with the fungus over a 12-week period. At pre-established time intervals two samples were withdrawn from the medium and analyzed by thermogravimetry and differential calorimetry, and the results were correlated with mass loss. Fungal activity was indicated by continuous decrease of sample mass. Modification of the wood because of the presence of the fungus was evidenced by structural changes that affected its thermal properties, both in respect to the hydrophilicity of the wood (evidenced mainly in desorption process) and in its decomposition behavior. The shape of DTG curves depends on the exposure time of wood to the action of microorganisms. The peak temperature assigned to the decomposition of wood components increases, while the global kinetic parameters for the main peak decrease with increasing exposure time of the wood to the attack by microorganisms. The increased characteristic temperatures of water desorption and cellulose decomposition processes and lower thermal stability could be explained by newly formed structures, mainly the oxidized ones. © 2010 Elsevier Ltd. All rights reserved. Source


Popescu C.-M.,Romanian Academy P Poni Institute Of Macromolecular Chemical | Popescu M.-C.,Romanian Academy P Poni Institute Of Macromolecular Chemical | Vasile C.,Romanian Academy P Poni Institute Of Macromolecular Chemical
Microchemical Journal | Year: 2010

The action of soft-rot fungus Chaetomium globosum has been studied. The decayed lime wood samples were observed for different periods of exposure. The degree of decay was determined by weight loss which was of 50.4% after 133 days. The samples were analyzed by FT-IR and 2D IR correlation spectroscopy. The intensity bands assigned to different vibrations from cellulose and hemicelluloses show a decrease, while the intensities of the bands assigned to C-O vibrations due to the formation of oxidized structures increase. At the same time, the intensity of the band assigned to C-O in metoxyl groups from lignin shows a decrease with increasing exposure time. The differences between reference and decayed wood spectra were examined in detail using 2D correlation spectroscopy and the second derivative analysis for two exposure time periods - of 0-70 days and 70-133 days. The formation of reactive species due to oxidation reactions induced by enzymes and the demethoxylation of the lignin structure was evidenced. © 2010 Elsevier B.V. All rights reserved. Source


Popescu C.-M.,Romanian Academy P Poni Institute Of Macromolecular Chemical | Popescu M.-C.,Romanian Academy P Poni Institute Of Macromolecular Chemical | Vasile C.,Romanian Academy P Poni Institute Of Macromolecular Chemical
Carbohydrate Polymers | Year: 2010

The changes in structure of lime wood (Tilia cordata Mill.) decayed by Trichoderma viride Pers. have been investigated by FT-IR and 2D IR correlation spectroscopy. Wood was exposed to fungi for different durations up to 84 days, with decay assessed through mass loss and FT-IR. A decrease of intensities bands assigned to different vibrations from cellulose and hemicelluloses, with increasing intensities of the bands assigned to C{single bond}O vibrations due to formation of oxidized structures was observed; and examined in details using 2D-correlation spectroscopy and the second derivative analysis in the exposure time range of 0-35 days. The formation of reactive species due to oxidation reactions induced by enzymes was evidenced. It has been also established that after longer degradation period oligomers and oxidized structures result, and finally small fragments containing carboxyl or carbonyl groups are formed, which lead to loss of structural integrity of the lime wood. © 2009 Elsevier Ltd. All rights reserved. Source

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