Thermal Reactions and Industrial Uses of Bark
A kinetic study indicated that the phenolic substances in Douglas-fir and red alder bark can be polymerized by high-temperature heating. Organic extractives that may be leached out by the action of water are condensed to water insolubles. Heat-treated bark is shown to be an appropriate material for the cleaning up of oil spills on water without contributing to high BOD and possible toxieity to fish. The oil absorption of bark, depending on its particle size, is two to seven times its weight.
A vacuum system was developed for hot pressing bark boards, which technnique avoids blister formation caused by the evolution of gases from condensation and dehydration reactions in thick boards. Bark boards made under an appropriate time-temperature schedule have both internal bond strength and bending modulus of rupture similar to bark boards made with 4.5% phenolic resin and subsequently pressed at a moderate time-temperature schedule, precluding polymerization of the bark extractives. Hot stacking increased the internal bond strength of boards.
Dimensional stability is the most significant property of these bark boards. Properly made bark boards have a much smaller thickness swelling and linear expansion than bark boards made with 4.5% phenolic resin after soaking in water for 72 hr.
Cnow, S., and K. J. Pickles. 1971. Thermal softening and degradation of wood and bark. Wood and Fiber 3(3): 166-178.nJohnson, E. S., ed. 1956. Wood particle board handbook. N.C. State Coll., Sch. Eng., Raleigh. 302 p.nLevin, E. D., N. D. Barabash, and A. A. Sinorov. 1971. Electron paramagnetic resonance study of the mechanism of semicoke formation. Khim. Drevesiny (Riga) 7:73-77. ABIPC 42:abstr. 2832 (original not seen).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.