Microstructural and physical aspects of heat treated wood. Part 1. Softwoods
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| Natura: | Artículo científico |
| Lingua: | en |
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Universidad del Bío Bío
2006
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| _version_ | 1876461326353563648 |
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| author | M.J. Boonstra |
| author_facet | M.J. Boonstra |
| contents | Microstructural and physical aspects of heat treated wood. Part 1. Softwoods M.J. Boonstra J.F. Rijsdijk C. Sander E. Kegel B. Tjeerdsma H. Militz J. van Acker M. Stevens Agrociencias softwood microscopy heat treatment Wood modification Heat treatment of wood is an effective method to improve the dimensional stability and durabilityagainst biodegradation. Optimisation of a two-stage heat treatment process at relatively mild conditions(<200°C) and its effect on the anatomical structure of softwoods were investigated by means of a lightand scanning electron microscopic analysis. Heat treatment did have an effect on the anatomical structureof wood, although this depends on the wood species considered and on the process method and conditionsused. Softwood species with narrow annual rings and/or an abrupt transition from earlywood into latewoodwere sensitive to tangential cracks in the latewood section. Radial cracks occurred mainly in impermeablewood species such as Norway spruce, caused by large stresses in the wood structure during treatment.Sapwood of treated pine species revealed some damage to parenchyma cells in the rays and epithelialcells around resin canals, whereas this phenomenon has not been noticed in the heartwood section.Treated radiata pine resulted in a very open and permeable wood structure limiting the applications ofthis species. Broken cell walls perpendicular to the fibre direction resulting in transverse ruptures havebeen noticed in treated softwood species. This contributes to abrupt fractures of treated wood as observedin bending tests which can lead to considerably different failure behavior after impact or mechanicalstress. In some treated softwood species maceration (small cracks between tracheids) was noticed afterheat treatment. Heat treatment did not cause damage to the ray parenchyma pit membranes, borderedpits and large window pit membranes; the margo fibrils appeared without damage. Compared to theother softwood timbers tested European grown Douglas fir was the timber that stands heat treatment thebest. 2006 artículo científico 0717-3644 https://www.redalyc.org/articulo.oa?id=48580306 en http://www.redalyc.org/revista.oa?id=485 Maderas. Ciencia y Tecnología application/pdf Universidad del Bío Bío Maderas. Ciencia y Tecnología (Chile) Num.3 Vol.8 |
| format | Artículo científico |
| id | redalyc_48580306 |
| institution | Redalyc |
| language | en |
| publishDate | 2006 |
| publisher | Universidad del Bío Bío |
| spellingShingle | Microstructural and physical aspects of heat treated wood. Part 1. Softwoods M.J. Boonstra Agrociencias softwood microscopy heat treatment Wood modification Microstructural and physical aspects of heat treated wood. Part 1. Softwoods M.J. Boonstra J.F. Rijsdijk C. Sander E. Kegel B. Tjeerdsma H. Militz J. van Acker M. Stevens Agrociencias softwood microscopy heat treatment Wood modification Heat treatment of wood is an effective method to improve the dimensional stability and durabilityagainst biodegradation. Optimisation of a two-stage heat treatment process at relatively mild conditions(<200°C) and its effect on the anatomical structure of softwoods were investigated by means of a lightand scanning electron microscopic analysis. Heat treatment did have an effect on the anatomical structureof wood, although this depends on the wood species considered and on the process method and conditionsused. Softwood species with narrow annual rings and/or an abrupt transition from earlywood into latewoodwere sensitive to tangential cracks in the latewood section. Radial cracks occurred mainly in impermeablewood species such as Norway spruce, caused by large stresses in the wood structure during treatment.Sapwood of treated pine species revealed some damage to parenchyma cells in the rays and epithelialcells around resin canals, whereas this phenomenon has not been noticed in the heartwood section.Treated radiata pine resulted in a very open and permeable wood structure limiting the applications ofthis species. Broken cell walls perpendicular to the fibre direction resulting in transverse ruptures havebeen noticed in treated softwood species. This contributes to abrupt fractures of treated wood as observedin bending tests which can lead to considerably different failure behavior after impact or mechanicalstress. In some treated softwood species maceration (small cracks between tracheids) was noticed afterheat treatment. Heat treatment did not cause damage to the ray parenchyma pit membranes, borderedpits and large window pit membranes; the margo fibrils appeared without damage. Compared to theother softwood timbers tested European grown Douglas fir was the timber that stands heat treatment thebest. 2006 artículo científico 0717-3644 https://www.redalyc.org/articulo.oa?id=48580306 en http://www.redalyc.org/revista.oa?id=485 Maderas. Ciencia y Tecnología application/pdf Universidad del Bío Bío Maderas. Ciencia y Tecnología (Chile) Num.3 Vol.8 |
| title | Microstructural and physical aspects of heat treated wood. Part 1. Softwoods |
| topic | Agrociencias softwood microscopy heat treatment Wood modification |
| url | https://www.redalyc.org/articulo.oa?id=48580306 |