Abstract
The technology of steam explosion was applied to pre-treat sub-alpine fir (Abies lasiocarpa (Hook.) Nutt.) lumber and to improve its drying characteristics. Effects of steam explosion on the appearance and structure of the lumber are discussed in this paper. The structure of the wood was examined using light microscope (LM) and scanning electron microscope (SEM). The following results were obtained. With increasing temperature, pressure, and explosion cycles the color of the lumber darkened gradually. No significant structural difference between treated and untreated samples was observed using LM when the treatments were carried out at temperatures below 130°C with ten explosion cycles (group A or B). Some fractures were observed in bordered pit pairs between tracheids after 20 explosion cycles at 130°C (group C). More fractures occurred in bordered pit pairs between earlywood tracheids at a temperature of 160°C (group D). More or less fractures in pits between ray parenchyma cells and earlywood tracheids were observed using SEM in all four cases of treatments. Although no change in bordered pits in the tracheid walls between group A and the control group was discovered, groups B, C, and D showed different extents of ruptures in bordered pits, which may lead to break aspirated pits and improve permeability. In these groups, wrinkles and separations in the inner tracheid walls and detachments in middle lamella also occurred and became more serious as temperature or cycles of the treatment increased.
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Acknowledgements
Forintek Canada Corporation would like to thank its industry members, Natural Resources Canada (Canadian Forest Service), and the Provinces of British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, Nova Scotia, New Brunswick, as well as Newfoundland and Labrador, for their guidance and financial support for this research. Special thanks to Mr. Jean Baribeault from Hydro Quebec for providing the steam explosion equipment and Mr. Bill Mundie from Weldwood of Canada Ltd. (West Fraser Timber) for providing the sub-alpine fir lumber.
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Zhang, Y., Cai, L. Effects of steam explosion on wood appearance and structure of sub-alpine fir. Wood Sci Technol 40, 427–436 (2006). https://doi.org/10.1007/s00226-005-0053-6
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DOI: https://doi.org/10.1007/s00226-005-0053-6