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Journal of Materials Science

, Volume 49, Issue 5, pp 2027–2034 | Cite as

Micromorphological studies of surface densified wood

  • Kristiina LaineEmail author
  • Kristoffer Segerholm
  • Magnus Wålinder
  • Lauri Rautkari
  • Graham Ormondroyd
  • Mark Hughes
  • Dennis Jones
Article

Abstract

Scots pine (Pinus sylvestris L.) wood was surface densified in its radial direction in an open press with one heated plate to obtain a higher density on the wood surface whilst retaining the overall thickness of the sample. This study investigated the effect of temperature (100, 150 and 200 °C) and press closing speed (5, 10 and 30 mm/min, giving closing times of 60, 30 and 10 s, respectively) on the micromorphology of the cell-wall, as well as changes occurring during set-recovery of the densified wood. The micromorphology was analysed using scanning electron microscopy (SEM) combined with a sample preparation technique based on ultraviolet-excimer laser ablation. Furthermore, the density profiles of the samples were measured. Low press temperature (100 °C) and short closing time (10 s) resulted in more deformation through the whole thickness, whilst increasing the temperature (150 and 200 °C) and prolonging the closing time (30 and 60 s) enabled more targeted deformation closer to the heated plate. The deformation occurred in the earlywood regions as curling and twisting of the radial cell-walls, however, no apparent cell-wall disruption or internal fracture was observed, even at low temperatures and fast press closing speed, nor after soaking and drying of the samples. In the SEM-analysis after soaking and drying, it was noticed that the cells did not completely recover their original form. Thus, part of the deformation was considered permanent perhaps due to viscoelastic flow and plastic deformation of the cell-wall components.

Keywords

Laser Ablation Closing Time Densified Wood Growth Ring Resin Canal 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

The authors wish to thank Joachim Seltman (SP, Sweden) and Marielle Henriksson (SP, Sweden) as well as Nick Laflin (Biocomposites Centre, UK) for technical support. The study was supported by the EcoBuild Centre, Stiftelsen Nils och Dorthi Troëdssons forskningsfond and the COST Action FP0904 in the form of a short-term-scientific-mission.

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Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Kristiina Laine
    • 1
    Email author
  • Kristoffer Segerholm
    • 2
    • 3
  • Magnus Wålinder
    • 3
  • Lauri Rautkari
    • 1
  • Graham Ormondroyd
    • 4
  • Mark Hughes
    • 1
  • Dennis Jones
    • 2
  1. 1.Department of Forest Products Technology, School of Chemical TechnologyAalto UniversityAaltoFinland
  2. 2.Wood TechnologySP Technical Research Institute of SwedenStockholmSweden
  3. 3.Division of Building MaterialsKTH – Royal Institute of TechnologyStockholmSweden
  4. 4.BioComposites CentreBangor UniversityBangorUK

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