Detection of Fungal Degradation at Low Weight Loss by Differential Scanning Calorimetry
Keywords:
Incipient decay, thermal analysis, differential scanning calorimetry (DSC), hybrid poplar, <i>Populus maximowiczii</i> x <i>trichocarpa</i>, <i>Lenzites trabea</i>Abstract
A thermo-analytical method to detect incipient fungal degradation was investigated. Hybrid poplar (Populus maximowiczii x trichocarpa) specimens were degraded by the brown-rot fungus Lenzites trabea and analyzed at five sequential, 3-day intervals to a weight loss of 5%. To measure the extent of decay, cold water, hot water, and sodium hydroxide solubilities, ethanol-benzene extractive content as well as lignin, holocellulose, and alpha-cellulose were determined. Viscometric analysis was conducted to determine changes in the weight average degree of polymerization (DPw), and thermal analysis by differential scanning calorimetry (DSC) was performed to determine endothermic transitions in the whole decayed wood, extractive-free wood, and holo- and alpha-cellulose. Chemical analyses provided results consistent with those expected in wood decayed by a brown-rot fungus. DPw changes of both holo- and alpha-cellulose were significant with regard to decay interval. Analysis of DSC data revealed that this methodology was a reliable means of evaluating fungal degradation in extractive-free wood and holo- and alpha-cellulose preparations from the decayed wood but not the whole wood.References
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