Effect of Moisture on The Flexural Properties of Commercial Oriented Strandboards
Keywords:
Bending, modulus of elasticity, modulus of rupture, strength and stiffness loss, structural wood composite, thickness swellingAbstract
Moisture content (MC), thickness swelling (TS), and bending properties of five commercial oriented strandboards (OSBs) made of two wood species were measured. The measurements were made after specimens were conditioned to equilibrium at 35, 55, 75, 85, 95% relative humidity (RH) and 24°C. It was shown that bending modulus of elasticity (MOE) and modulus of rupture (MOR) decreased with increases in board MC. Both MOE and MOR followed a linear relation with MC over the given MC change. Thickness swelling of these OSBs was shown to have a large nonrecoverable component, which mainly occurred with MC increases above the 8 to 10% level. For an MC change from 4 to 24%, the combined effect of increased MC and TS led to an average MOE loss of 72% in the parallel direction and 83% in the perpendicular direction; and to an average MOR loss of 58% in the parallel direction and 67% in the perpendicular direction. Predictive equations expressing the bending MOE/MOR and thickness swelling as a function of MC and MOE/MOR loss as a function of thickness swelling were established for various products.References
American Society For Testing and Materials. 1984. Establishing structural grades and related allowable properties for visually-graded lumber. ASTM D 245-81. Philadelphia, PA.nAmerican Society For Testing and Materials. 1983. Evaluating the properties of wood-based fiber and particle panel materials. ASTM D 1037-78, Section 4: 225-267. Philadelphia, PA.nAnonymous. 1993. Siempelkamp promotion literature. 1 p.nGeimer, R. L. 1982. Dimensional stability of flakeboards as affected by board specific gravity and flake alignment. Forest Prod. J. 32(8):44-52.nGerhards, C. C. 1982. Effect of moisture content and temperature on the mechanical properties of wood: An analysis of immediate effects. Wood Fiber 14(1):4-36.3.nSAS Institute Inc. 1994. SAS/STAT User's Guide. Version 6. SAS Institute Inc. Cary, NC. 1688 pp.nSuchsland, Otto. 1973. Hygroscopic thickness swelling and related properties of selected commercial particle-boards. Forest Prod. J. 23(7):26-30.nUSDA Forest Service. 1987. Wood handbook: Wood as an engineering material. Agric. Handb. 72. U.S. Department of Agriculture, Washington D.C. 466 pp.nWilson, T. R. C. 1932. Strength-moisture relations for wood. Technical Bulletin No. 282. U.S. Depanment of Agriculture, Washington D.C. 88 pp.nHalligan, A. F. 1970. A review of thickness swelling in particleboard. Wood Sci. Technol. 4:301-312.nHalligan, A. F., and A. P. Schniewind. 1974. Prediction of particleboard mechanical properties at various moisture contents. Wood Sci. Technol. 8:68-78.nHiziroglu, S. S. 1989. Swelling stresses and deformations in wood composites. Ph.D. dissertation, Michigan State University, East Lansing, MI. 160 pp.nKelly, M. W. 1977. Critical literature review of relationships between processing parameters and physical properties of particleboard. Gen. Tech. Rep. FPL-20. USDA Forest Service, Forest Products Laboratory, Madison, WI.nLehmann, W. F. 1978. Cyclic moisture conditions and their effect on strength and stability of structural flake-board. Forest Prod. J. 28(6):23-31.nPu, Jianhua, R. C. Tang, and W. C. Davis. 1991. Creep behavior of commercial oriented strandboard under high relative humidity. Forest Prod. J. 42(4):49-54.n
Downloads
Published
Issue
Section
License
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.
