Elastic Properties of Hot-Pressed Aspen Strands
Keywords:
Wood-strand composite, strand elastic properties, hot-pressing, oriented strand panelsAbstract
The in-situ elastic constants of a wood strand are affected by the physical changes that it experiences during the manufacturing process of a wood-strand composite. The hot-pressing conditions and the location in the mat govern the environmental conditions surrounding each strand, which in turn influence the adhesive cure and final strand density. Few studies have examined systematically the changes in strand elastic constants as influenced by strand density, location, and/or resin content. Understanding these interactions is important to determine the role of pressing variables on altering strand properties and to accurately model structure-property relationships in wood-strand composites. The following presentation will discuss the results of a study conducted to investigate the influence of strand location and resin content on changes in strand density and elastic properties within a pressed panel. In-situ properties of the strands were evaluated after isolating the strands from resinated hot-pressed oriented strandboards. Response models based on mixture design, considering the hot-pressing effects, were developed to predict the in-situ elastic constants of strands. Addition of resin positively influenced the strand stiffness and decreased strand's Poisson's ratio. Strand stiffness greatly increased with increasing resin content in regions of higher densification.References
Andrews, C. K., P. M. Winistorfer, and R. M. Bennett. 2001. The influence of furnish moisture content and press closure rate on the formation of the vertical density profile in oriented strandboard. Forest Prod. J.51(5):32-39.nAmerican Society for Testing and Materials (ASTM). 2000. Standard Test Methods for Tensile Properties of Plastics. Standard D 638-99. American Society of Testing and Materials. Volume 8.01. Conshohocken, PA.nAmerican Society for Testing and Materials (ASTM). 2001. Standard Test Methods for Specific Gravity of Wood and Wood-Based Materials. Standard D 2395-93. American Society of Testing and Materials. Volume 4.10.nBodig J., and J. R. Goodman. 1973. Prediction of elastic properties for wood. Wood Science5(4):249-264.nBodig J., and B. A. Jayne. 1982. Mechanics of wood and wood composites. Van Nostrand Reinhold Company, New York, NY.nBreyfogle III, F. W. 1992. Statistical Methods for Testing, Development, and Manufacturing. John Wiley & Sons, Inc., New York, NY.nCasey, L. J. 1987. Changes in wood-flake properties in relation to heat, moisture, and pressure during flakeboard manufacture. Master's Thesis, Dept. of Forestry and Forest Products, Virginia Polytechnic Institute and State University, Blacksburg, VA. 162 pp.nCornell, J. A. 1981. Experiments with mixtures: Designs, Models, and the Analysis of Mixture Data. John Wiley & Sons, New York, NY.nGardner, D. J., D. W. Gunnells, M. P. Wolcott, and L. Amos. 1993. Changes in wood polymers during the pressing of wood-composites. In Cellulosics: Chemical, Biochemical and Material Aspects. Editors J. F. Kennedy, G. O. Phillips, and P. A. Williams. Ellis Horwood, New York, NY. pp. 513-518.nGeimer, R. L., R. J. Mahoney, S. P. Loehnertz, and R. W. Meyer. 1985. Influence of processing-induced damage on strength of flakes and flakeboards. USDA Forest Service Research Paper FPL 463. 15 pp.nJahan-Latibari, A. 1982a. The response of aspen flakes and flake-board to flake surface modifications. Proceedings of 6th Washington State University International Symposium on Particleboard. pp. 331-351.nJahan-Latibari, A. 1982b. The response of aspen flakes and flake-board to flake surface modifications. Ph.D. Dissertation, Washington State University. 135 pp.nJahan-Latibari, A., W. E. Johns, and R. V. Subramanian. 1984. Technique for isolating flakes from the pressed mat. Forest Products Journal.34(2):33-34.nJohnson, S. E. and F. A. Kamke. 1992. Quantitative analysis of gross adhesive penetration in wood using fluorescence microscopy. Journal of Adhesion.40:47-61.nJones, R. M. 1999. Mechanics of composite materials. 2nd Edition. Taylor & Francis, Philadelphia, PA.nKamke, F.A. and L. J. Casey. 1988a. Fundamentals of flakeboard manufacture: internal-mat conditions. Forest Products Journal.38(6):38-44.nKellogg, R.M. and G. Ifju. 1962. Influence of specific gravity and certain other factors on the tensile properties of wood. Forest Products Journal.12(10):463-470.nLaborie, M-P. G. 2002. Investigation of the wood/phenolformaldehyde adhesive interphase morphology. Ph.D. Disseration. Virginia Polytechnic Institute and State University, Blacksburg, VA.nMahoney, R. J. 1980. Physical changes in wood particles induced by the particleboard hot-pressing operation. M.S. Thesis. Washington State University. 35 pp.nMarra, A. A. 1992. Technology of Wood Bonding Principles in Practice. Van Nostrand Reinhold, New York, NY.nMeyers, K. L. 2001. Impact of strand geometry and orientation on mechanical properties of strand composites. Master's Thesis. Dept. of Civil and Environmental Engineering, Washington State University. 115 pp.nPalka, L. C. 1973. Predicting the effect of specific gravity, moisture content, temperature and strain rate on the elastic properties of softwoods. Wood Science and Technology.7:127-141.nPrice, E. W. 1976. Determining tensile properties of sweet-gum veneer flakes. Forest Products Journal.26(10):50-53.nSAS Institute Inc. 1999. SAS for Windows Version 8. Cary, North Carolina.nYadama, V. 2002. Characterization and modeling of oriented strand composites. Ph.D. Dissertation. Washington State University.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.
