Thermogravimetric Evaluation of Fungal Degradation of Wood
Keywords:Thermal analysis, isothermal TG, dynamic TG, <i>Betula alleghaniensis</i>, white rot, brown rot, <i>Polyporus versicolor</i>, <i>Poria monticola</i>, biodegradation, decay
AbstractYellow birch (Betula alleghaniensis Brit.) was degraded by a white rot fungus (Polyporus versicolor L. ex Fr.; now Coriolus versicolor (L.) Quél.) and a brown rot fungus (Poria monticola Murr.; now Poria placenta (Fr.) Cke.) under controlled conditions. Samples of known weight loss from fungi were milled to pass a 40-mesh screen, oven-dried, and then measured for rate of mass loss over selected temperature ranges. Rates of mass loss of nominal 4-mg samples were obtained isothermally in flowing oxygen using a thermo-gravimetric (TG) system containing a Cahn electrobalance. Activation energy (E) was found using zero-order kinetics for the initial mass loss. White-rotted birch (to 60% weight loss) had an E of 35 to 43 kcal/mole over the range of approximately 190 to 210 C. On the basis of TG data, the weight loss from fungal attack could be predicted within about 5%. Brown-rotted birch had more variation in E (30 to 44 kcal/mole), over a temperature range of 170 to 195 C. The rate of mass loss of brown-rotted birch (to 52% weight loss) was more sensitive to temperature because of the known nonlinear decrease in cellulose DP during fungal attack. Dynamic thermogravimetry, a much simpler method, indicated a similar degree of instability from fungal attack as did the isothermal tests. TG appears to be a viable research method to evaluate fungal attack of wood.
Beall, F. C. 1968. Thermal degradation analysis of wood and wood components. Ph.D. thesis, SUNY Coll. of For., Syracuse, N.Y. 240 pp.nCowling, E. B. 1961. Comparative biochemistry of the decay of sweetgum sapwood by white-rot and brown-rot fungi. USDA Tech. Bull. No. 1258. 79 pp.nFlynn, J. H., and L. A. Wall. 1966. General treatment of the thermography of polymers. J. Res. NBS70 A (6): 487-523.nSmith, R. S. 1975. Respiration methods to follow wood decay and evaluate toximetric potential of wood preservatives. Mat. Organ.10(4): 241-253.nTimell, T. E. 1965. Wood and bark polysaccharides. Pages 127-156 in W. A. Côté, ed. Cellular ultrastructure of woody plants. Syracuse Univ. Press, Syracuse, N.Y.n
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.