An Optimal Thermo-Hydro-Mechanical Densification (THM) Process for Densifying Balsam Fir Wood

To better utilize low-density softwood, a thermo-hydro-mechanical densification process performed in an open system was studied to enable the manufacture of densified wood with a hard surface, strong bonding, and good dimensional stability. This study was aimed at optimizing three densification parameters, i.e., compression ratio (CR), temperature, and time, for balsam fir (Abies balsamea (L.) Mill.). The Brinell surface hardness, bond strength, and thickness recovery ratio of densified fir were examined. It was found that the optimal densification parameters were a CR of 60%, a temperature of 230 oC, and a time of 20 minutes. The surface hardness and bond strength of optimized densified fir were about 30 and 8 MPa, respectively. The thickness recovery ratio of the densified fir after a 2-hour cold water soaking and another 2-hour boiling treatment was about 10%. Because the densified fir in this study was used for indoor applications only, its thickness recovery ratio could be minimal under conditions of use.

[1]  M. Hughes,et al.  Hardness and density profile of surface densified and thermally modified Scots pine in relation to degree of densification , 2013, Journal of Materials Science.

[2]  L. Li.  RECOVERY OF MECHANICALLY INDUCED RESIDUAL STRESSES IN DENSIFIED SOFTWOODS CREATED DURING A DENSIFICATION PROCESS , 2012 .

[3]  Ahmed Koubaa,et al.  Densification of wood veneers by compression combined with heat and steam , 2011, European Journal of Wood and Wood Products.

[4]  F. Kamke,et al.  Transverse compression behavior of wood in saturated steam at 150-170°C. , 2010 .

[5]  S. Poncsák,et al.  Effect of heat treatment on the mechanical properties of North American jack pine: thermogravimetric study , 2010, Journal of Materials Science.

[6]  M. Gong,et al.  Interactive effect of surface densification and post-heat-treatment on aspen wood , 2010 .

[7]  Robert J. Ross,et al.  Wood handbook : wood as an engineering material , 2010 .

[8]  F. Kamke,et al.  Density profile and morphology of viscoelastic thermal compressed wood , 2009, Wood Science and Technology.

[9]  R. Rowell,et al.  Fixation of compressive deformation in wood by pre-steaming , 2008 .

[10]  Y. Sasaki,et al.  COMPRESSIVE DEFORMATION PROCESS OF JAPANESE CEDAR (CRYPTOMERIA JAPONICA ) , 2007 .

[11]  M. Gong,et al.  Optimization of pressing parameters for mechanically surface-densified aspen , 2007 .

[12]  A. Halligan.  A review of thickness swelling in particleboard , 1970, Wood Science and Technology.

[13]  P. Blanchet,et al.  Comparative study of four adhesives used as binder in engineered wood parquet flooring , 2003 .

[14]  P. Navi,et al.  Effects of Thermo-Hydro-Mechanical Treatment on the Structure and Properties of Wood , 2000 .

[15]  T. Ohgama,et al.  Tangential Youngs Modulus of Coniferous Early Wood Investigated Using Cell Models , 1999 .

[16]  Y. Shinoda,et al.  Compressive-Molding of Wood by High-Pressure Steam-Treatment: Part 1. Development of Compressively Molded Squares from Thinnings , 1998 .

[17]  R. Rowell,et al.  Treatments that enhance physical properties of wood , 1987 .

[18]  L. Salmén.  Viscoelastic properties ofin situ lignin under water-saturated conditions , 1984 .

[19]  G. M. Irvine,et al.  The glass transitions of lignin and hemicellulose and their measurement by differential thermal analysis , 1984 .

[20]  E. L. Back,et al.  Glass transitions of wood components hold implications for molding and pulping processes [Wood and paper materials]. , 1982 .

[21]  L. Salmén,et al.  Temperature and water induced softening behaviour of wood fiber based materials , 1982 .

[22]  V. Sergeeva,et al.  Variability of the properties of Spruce wood fibres under the influence of heating. , 1960 .