Effects of semi-isostatic densification on anatomy and cell-shape recovery on soaking
-
Jonas Blomberg
Abstract
Images obtained by scanning electron microscopy (SEM) helped to clarify the question as to how anatomy influences the deformation on compression and the springback of densified wood on water soaking. Transverse sections of Norway spruce (Picea abies), Scots pine (Pinus sylvestris), black alder (Alnus glutinosa), Swedish aspen (Populus tremula), European birch (Betula pubescens), European beech (Fagus sylvatica) and pedunculate oak (Quercus robur) were studied. Wood is reinforced with rays in the radial direction and with dense latewood in the tangential direction. When strained radially, rays buckle or tilt tangentially. Softwoods were mainly compressed radially, owing to low number of rays and since latewood is much denser than earlywood. The diffuse-porous hardwoods with low density variation between latewood and earlywood were mainly deformed tangentially, except birch, which has high density at the annual ring border and is mainly compressed radially. The ring-porous hardwoods were relatively equally deformed in the radial and tangential directions because of the high number of rays and high latewood density. Moisture-induced springback (shape recovery) was proportional to the degree of compression. Rays remained deformed, which also influenced the surrounding wood. Longitudinal wood cells almost resumed their original shape. Wood with low density and a low degree of compression showed the highest structural recovery. Shearing deformation was particularly pronounced and permanent in woods with high strength anisotropy. Thin-walled and sheared cells, such as earlywood in softwood, tended to crack on compression. Cracks usually stopped at the middle lamella and had a lesser influence on strength properties than for lumen-to-lumen cracks.
References
Ando, K., Onda, H. (1999) Mechanism for deformation of wood as a honeycomb structure I: effect of anatomy on the initial deformation process during radial compression. J. Wood Sci.45:120–126.10.1007/BF01192328Suche in Google Scholar
Arakawa, T., Funato, M., Hoshino, A. (1998) Development of a novel treatment process and its applications. In: Proceedings of the 29th Annual Meeting of the IRG, Maastricht, Netherlands. Document IRG-WP-98-40111.Suche in Google Scholar
Back, E.L., Allen, L.H. Pitch Control, Wood Resin and Deresination. Tappi Press, Atlanta, GA, 2000.Suche in Google Scholar
Blomberg, J. (2005) Elastic strain at semi-isostatic compression of Scots pine (Pinus sylvestris). J. Wood Sci.51:401–404.10.1007/s10086-004-0666-7Suche in Google Scholar
Blomberg, J., Persson, B. (2004) Plastic deformation in small clear pieces of Scots pine (Pinus sylvestris) during densification with the CaLignum process. J. Wood Sci.50:307–314.10.1007/s10086-003-0566-2Suche in Google Scholar
Blomberg, J., Persson, B. (2005) An algorithm for comparing density in CT-images taken before and after compression of Pinus sylvestris. Holz Roh Werkst.63:23–29.10.1007/s00107-004-0544-4Suche in Google Scholar
Blomberg, J., Persson, B., Blomberg, A. (2005) Effects of semi-isostatic densification of wood on the variation in strength properties with density. Wood Sci. Technol.39:339–350.10.1007/s00226-005-0290-8Suche in Google Scholar
Bodig, J. (1965) The effect of anatomy on the initial stress-strain relationship in transverse compression. For. Prod. J.15:197–202.Suche in Google Scholar
Bucur, V., Garros, S., Barlow, C.Y. (2000) The effect of hydrostatic pressure on physical properties and microstructure of spruce and cherry. Holzforschung54:83–92.10.1515/HF.2000.013Suche in Google Scholar
Ellis, S., Steiner, P. (2002) The behaviour of five wood species in compression. IAWA J.23:201–211.10.1163/22941932-90000298Suche in Google Scholar
Johannisson, T.G. (1994) High pressure forming of body parts using flexible tools. Sheet Met. Ind.71:20–22.Suche in Google Scholar
Kellogg, R.M., Wangaard, F.F. (1969) Variation in the cell-wall density of wood. Wood Fiber1:180–204.Suche in Google Scholar
Kennedy, R.W. (1968) Wood in transverse compression. For. Prod. J.18:36–40.Suche in Google Scholar
Kollmann, F.F.P. (1959) The problem of transverse compressive strength of timber. Holzforschung Holzverwertung11:109–121.Suche in Google Scholar
Kunesh, R.H. (1961) The inelastic behaviour of wood: a new concept for improved panel forming processes. For. Prod. J.11:395–406.Suche in Google Scholar
Kunesh, R.H. (1968) Strength and elastic properties of wood in transverse compression. For. Prod. J.18:65–72.Suche in Google Scholar
Lindhe, C., Castwall, L. (1997) Process for producing hard elements of wood. U.S Patent No. 5,678,618.Suche in Google Scholar
Richter, H.G., Dallwitz, M.J. (2000 onwards) Commercial timbers: descriptions, illustrations, identification and information retrieval. Online: http://delta-intkey.com/wood/english/index.htm (accessed May 2005).Suche in Google Scholar
Russ, J.C. The Image Processing Handbook. 2nd ed. CRC, Boca Raton, FL, 1995.Suche in Google Scholar
Sandberg, D. (1998) Inverkan av isostatisk komprimering på cellstrukturen (The influence of isostatic compression on the cell wall structure of wood). Technical report TRITA-TRÄ-R-98-35. Royal Institute of Technology, Stockholm, Sweden.Suche in Google Scholar
Schoch, W., Heller, I., Schweingruber, F.H., Kienast, F. (2004) Wood anatomy of central European Species. Online version: http://www.woodanatomy.ch/ (accessed May 2005).Suche in Google Scholar
Skötte, A. (1976) Quintus sheet-metal forming presses – a new means for metal forming with high pressures and single tools. Sheet Met. Ind.53:212, 215–216, 219–220.Suche in Google Scholar
Tabarsa, T., Chui, Y.H. (2001) Characterizing microscopic behavior of wood under transverse compression. Part II. Effect of species and loading direction. Wood Fiber Sci.33:223–232.Suche in Google Scholar
Trenard, Y. (1977) Study of the isostatic compressibility of some timbers. Holzforschung31:166–171.10.1515/hfsg.1977.31.5.166Suche in Google Scholar
Wingate-Hill, R. (1983) A review of processes which involve compressing wood perpendicular to the grain. Aust. For. Res.13:151–164.Suche in Google Scholar
©2006 by Walter de Gruyter Berlin New York
Artikel in diesem Heft
- Brightness stabilisation of bleached high-yield pulps by novel sulfur-containing inhibitors
- Application of UV-Vis and resonance Raman spectroscopy to study bleaching and photoyellowing of thermomechanical pulps
- Characteristics of NAEM salt-catalyzed alcohol organosolv pulping as a biorefinery
- Effect of poly(ethylene oxide) molecular mass on miscibility and hydrogen bonding with lignin
- Calculation of the relative bonded area and scattering coefficient from sheet density and fibre shape
- Formic and acetic acids in archaeological wood. A comparison between the Vasa Warship, the Bremen Cog, the Oberländer Boat and the Danish Viking Ships
- Time-domain 1H NMR characterization of the liquid phase in greenwood
- Chemical reaction of alkoxysilane molecules in wood modified with silanol groups
- Dimensional stability of MDF panels produced from heat-treated fibres
- Multivariate modeling of MDF panel properties in relation to wood fiber characteristics
- Viscoelastic behaviour of solid wood under compressive loading
- The creep of wood destabilized by change in moisture content. Part 3: The influence of changing moisture history on creep behavior
- Air permeability of aspen veneer and glueline: Experimentation and implications
- Fracture cleavage analysis of PVAc latex adhesives: Influence of phenolic additives
- Effect of a waterproof agent on gypsum particleboard properties
- Effects of semi-isostatic densification on anatomy and cell-shape recovery on soaking
- Analytical tools to predict changes in properties of oriented strandboard exposed to the fungus Postia placenta
- The effect of CaCl2 on growth rate, wood decay and oxalic acid accumulation in Serpula lacrymans and related brown-rot fungi
Artikel in diesem Heft
- Brightness stabilisation of bleached high-yield pulps by novel sulfur-containing inhibitors
- Application of UV-Vis and resonance Raman spectroscopy to study bleaching and photoyellowing of thermomechanical pulps
- Characteristics of NAEM salt-catalyzed alcohol organosolv pulping as a biorefinery
- Effect of poly(ethylene oxide) molecular mass on miscibility and hydrogen bonding with lignin
- Calculation of the relative bonded area and scattering coefficient from sheet density and fibre shape
- Formic and acetic acids in archaeological wood. A comparison between the Vasa Warship, the Bremen Cog, the Oberländer Boat and the Danish Viking Ships
- Time-domain 1H NMR characterization of the liquid phase in greenwood
- Chemical reaction of alkoxysilane molecules in wood modified with silanol groups
- Dimensional stability of MDF panels produced from heat-treated fibres
- Multivariate modeling of MDF panel properties in relation to wood fiber characteristics
- Viscoelastic behaviour of solid wood under compressive loading
- The creep of wood destabilized by change in moisture content. Part 3: The influence of changing moisture history on creep behavior
- Air permeability of aspen veneer and glueline: Experimentation and implications
- Fracture cleavage analysis of PVAc latex adhesives: Influence of phenolic additives
- Effect of a waterproof agent on gypsum particleboard properties
- Effects of semi-isostatic densification on anatomy and cell-shape recovery on soaking
- Analytical tools to predict changes in properties of oriented strandboard exposed to the fungus Postia placenta
- The effect of CaCl2 on growth rate, wood decay and oxalic acid accumulation in Serpula lacrymans and related brown-rot fungi
