Effect of Panel Moisture Content and Density on Moisture Movement in MDF
Keywords:
Medium density fiberboard, effective water conductivity, diffusion coefficient, sorption isotherm, moisture content, densityAbstract
This study examined the effect of medium density fiberboard (MDF) density and sorption state on the sorption isotherms and the effect of panel moisture content and density on the effective water conductivity and diffusion coefficient of MDF panels. A total of 39 laboratory-made MDF panels with dimensions 650 mm X 650 mm X 12 mm divided into 3 density groups (540 kg/m3, 650 kg/m3, and 800 kg/m3) was produced. The surface layers of each panel were removed, and the thickness of the remaining core layer of homogeneous density was reduced by sanding to 6 mm. The sorption isotherms were determined by exposing MDF samples to controlled relative humidities. The effective water conductivity was determined by the instantaneous profile method. Medium density fiberboard from all density levels displayed a marked sorption hysteresis. Both in adsorption and in desorption, the MDF specimens with higher density levels equilibrated at higher levels of moisture content. Moisture content had a stronger effect than density on the effective water conductivity. In desorption, the higher the moisture content level, the higher the effective water conductivity. Conversely, in adsorption, the effective water conductivity decreased as moisture content increased. The effective water conductivity in desorption and the diffusion coefficients both in desorption and adsorption were significantly higher for panels with a density of 540 kg/m3 than for densities of 650 and 800 kg/m3. In adsorption, the effective water conductivity of panels with a density of 540 kg/m3 was significantly higher than for a density of 800 kg/m3.References
American Society of Testing and Materials (ASTM). E 96-94. 1994. Standard test methods for water vapor transmission of materials. Annual Book of ASTM Standards, Vol. 04.06. ASTM, Philadelphia, West Conshohocken, PA.nBolton, A. J., and P. E. Humphrey. 1994. The permeability of wood-based composite materials. Part 1. A review of the literature and some unpublished work. Holzforschung 48:95-100.nCloutier, A., and Y. Fortin. 1991. Moisture content-water potential relationship of wood from saturated to dry conditions. Wood Sci. Technol. 25(4):263-280.nCloutier, A., and Y. Fortin. 1993. A model of moisture movement in wood based on water potential and the determination of the effective water conductivity. Wood Sci. Technol. 27:95-114.nCloutier, A., Y. Fortin., and G. Dhatt. 1992. A wood drying finite element model based on the water potential concept. Drying Technol. 10(5):1151-1181.nDefo, M., Y. Fortin, and A. Cloutier. 1999. Determination of the effective water conductivity of sugar maple sapwood and white spruce heartwood under vacuum. Wood Fiber Sci. 31(4):343-359.nDefo, M., A. Cloutier, and Y. Fortin. 2000. Modeling vacuum-contact drying of wood: The water potential approach. Drying Technol. 18(8): 1737-1778.nFischer, A., and G. Merkle. 1963. Testing of particle-board surfaces. (In German with summary in English) Holz Roh-Werkst. 21:96-104.nFortin, Y. 1979. Moisture content-matrix potential relationship and water flow properties of wood at high moisture contents. Ph.D. dissertation, The University of British Columbia, Vancouver, BC.nGreubel, D., and H. Drewes. 1987. Ermittlung der Sorptionisothermen von Holzwekstoffen bei verschiedenen Temperaturen mit einem neuen Meßverfahren. (In German) Holz Roh-Werkst. 45:289-295.nHernandez, R. 1989. Influence des composantes secondaires et du contrefil sur les propriétés physico-méchaniques des bois tropicaux. Thèse de Ph.D. (In French) Département des sciences du bois. Université Laval, Québec, Canada. 186 pp.nJann, O., and H. J. Depple. 1990. Zur Berücksichtigung der Materialfeuchte bei der Formaldehydmessung von Spanplatten. (In German) Holz Roh-Werkst. 48:365-369.nKamke, F. A., and S. C. Zylkowski. 1989. Effects of wood-based panel characteristics on thermal conduçtivity. Forest Prod. J. 39(5): 19-24.nKehr, E. 1966. On the improvement of particleboard surfaces. (In German with summary in English) Holz Roh-Werkst. 7:295-305.nKoponen, H. 1984. Dependencies of moisture diffusion coefficients of wood and wooden panels on moisture content and wood properties. Paperi ja Puu 12:740-745.nLundgren, A. 1958. The hygroscopic properties of fibre-board. (In German with summary in English) Holz Roh-Werkst. 16(4): 122-127.nNelson, M. N. Jr. 1983. A model for sorption of water vapor by wood cellulosic materials. Wood Fiber Sci. 15(1):8-22.nPlanche, A. 1999. Caractérisation mécano-physique des panneaux MDF. (In French). Revue des composites et des matériaux avancés 9:32-50.nRoffael, E., and A. Schneider. 1979. On the sorption behavior of wood particleboards. II. Effect of wood species on the equilibrium moisture content. (In German with summary in English). Holz Roh-Werkst. 37(7):259-264.nRosenkilde, A., and O. Söderström. 1997. Surface phenomena during drying of MDF. Holzforschung 51:79-82.nSamuelsson, A., and O. Söderström. 1994. Measurements of surface emission factors in wood drying. Pages 107-113 in A. Haslett and N. F. Layther, eds. COS. Proc. 4th IUFRO International Wood Drying Conference, Rotorua, New Zealand.nSchneider, A., E. Roffael, and H. A. May. 1982. Investigations on the influence of density resin level and flake dimensions on the sorption behavior and thickness swelling of particleboards. (In German with summary in English.) Holz Roh-Werkst. 40:339-344.nSeifert, J. 1972. Influences on the sorption of wood based materials. (In German with summary in English) Holz Roh-Werkst. 30:99-111.nSekino, N., A. Suimatsu, H. Kohrai, and E. Yasui. 1998. Measurements of sorption isotherms of selected commercial wood-based panels and predictions of moisture content changes in service. Wood Assoc. Mag. 45(3):237-243.nSiau, J. F. 1995. Wood: Influence of moisture to its physical properties. Department of Wood Science and Forest Products, Virginia Polytechnic Institute and State University, Blacksburg, VA. 227 pp.nSuchsland, O. 1972. Linear hygroscopic expansion of selected commercial particleboards. Forest Prod. J. 22(11):28-32.nSuchsland, O., and J. D. McNatt. 1986. Computer simulation of laminated wood panel warping. Forest Prod. J. 36(11/12):16-23.nTremblay, C., A. Cloutier, and B. Grandjean. 1999. Experimental determination of the ratio of vapor diffusion to the total water movement in wood during drying. Wood Fiber Sci. 31(3):235-248.nVital, B. R., and J. B. Wilson. 1979. Factors affecting the water adsorption of particleboard and flakeboard. Pages 97-101 in USDA Forest Service. Forest Products Laboratory. Proc. Wood Moisture Content-Temperature and Humidity Relationships Symposium, Virginia Polytechnic Institute and State University, Blacksburg, VA.nWu, Q. L. 1999. Application of Nelson's sorption isotherm to wood composites and overlays. Wood Fiber Sci. 31(2): 187-191.nWu, Q. L., and O. Suchsland. 1996. Prediction of moisture content and moisture gradient of an overlaid particle-board. Wood Fiber Sci. 28(2):227-239.nWu, Q. L., and Y. Ren. 2000. Characterization of sorption behavior of oriented strandboard under long-term cyclic humidity exposure condition. Wood Fiber Sci. 32(2):404-418.n
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