Changes in Nanostructure of Wood Cell Wall during Deformation
| Autor: | Marko Peura, Seppo Andersson, Ari Salmi, Mika Torkkeli, Ritva Serimaa, Edward Hæggström, Timo Karppinen |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
040101 forestry
Nanostructure Materials science Softwood Mechanical Engineering 04 agricultural and veterinary sciences 02 engineering and technology 15. Life on land 021001 nanoscience & nanotechnology Condensed Matter Physics Poisson's ratio chemistry.chemical_compound symbols.namesake chemistry Mechanics of Materials Ultimate tensile strength symbols 0401 agriculture forestry and fisheries General Materials Science Microfibril Crystallite Deformation (engineering) Cellulose Composite material 0210 nano-technology |
| Zdroj: | Materials Science Forum. 599:126-136 |
| ISSN: | 1662-9752 |
| Popis: | The excellent mechanical properties of wood arise from its cellular and cell wall structure. X-ray scattering, ultrasound, and mechanical testing is combined to study the effects of strain on crystalline cellulose in wood. Results for dry and re-moistened softwood samples are reviewed and new results are presented for native, never-dried samples of Silver birch. When softwood is stretched parallel to the cell axis, the mean microfibril angle diminishes significantly in compression wood, but only slightly in clear wood. The cellulose chains in the crystallites elongate and their distance diminishes. In the never-dried Silver birch samples, axial strain caused the mode of the microfibril angle distribution to slightly decrease from the initial value of 14 degrees to 12 degrees. Unlike in softwood, in never-dried birch crystalline cellulose showed auxetic tensile behaviour. The distance of the chains increased and the X-ray Poisson ratio νca was negative, -0.3 ± 0.2. Dehydration of never-dried Silver birch caused no difference to the microfibril angle distribution. |
| Databáze: | OpenAIRE |
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