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Inverkan av isostatisk komprimering på cellstrukturen
Kungliga Tekniska Högskolan. (Virkeslära)
1998 (Swedish)Report (Other academic)Alternative title
The influence of isostatic compression on the cell wall structure of wood. (English)
Abstract [sv]

Furuprover har komprimerats isostatiskt vid rumstemperatur i syfte att utvärdera vad som sker i cellstrukturen vid stora deformationer. Provema hade antingen stående eller liggande årsringar. Fuktkvoten vid komprimeringen var 10 %. Komprimeringsgraden har bestämts samt den återsvällning som erhålls när de komprimerade provema fuktas upp i vatten. Förändringar i cellstrukturen undersöktes i ESEM (Environmental Scanning Electron Microscope).

Komprimeringen var 2,3 gånger, vilket innebar att densiteten ökade från i medeltal 539 kg/m3till 1218 kg/m3. Vårveden komprimerades betydligt mer än sommarveden. Komprimeringen var störst i radiell riktning som en följd av att sommarveden ej motverkade deformationen av vårveden, vilket är fallet i den tangentiella riktningen. I longitudinell riktning var komprimeringen mycket liten.

Vid uppfuktningen av de komprimerade provema återgick komprimeringen till 90 %. I radiell riktning var återsvällningen 4 gånger större än i tangentiell riktning.

Någon inverkan av årsringsorienteringen kunde inte påvisas. Vid ESEM-studien kunde omfattande sprickbildning i cellväggarna observeras i både vår- och sommarveden.

Abstract [en]

The aim of this study was to evaluate the response of the cellwall structure in Scots pine

(Pinus sylvestris L.) samples to an isostatic compression. The annual ring orientation of the

samples was either radial or tangential. The compression set of the each samples was

determined during compression at a mean moisture content of 10 % and a temperature of 20°C. The structural changes were investigated in the Environmental Scanning Electron Microscope (ESEM).

The samples were compressed between 50 to 70 % of their original thicknesses, which means the density of the samples was between 539 Kg/m3 to 1218 Kg/m3, according to composite mechanic, we can assume that the early and latewood are in parallel in the radial direction. This suggests that in the radial direction compared to the latewood the earlywood will be compressed significantly. The longitudinal compression was insignificant.

The compressed wood retained up to 90 % of its original dimension when it was immersed in water. The swelling in the radial direction was four times greater than in the tangential direction.

Cracks as a result of the compression deformation were observed both in the early-and late wood cellwalls.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 1998. , 11 p.
Series
TRITA-TRÄ R-98-35, ISSN 1104-2117 ; 35
Keyword [en]
wood, densfication, Scots pine, ESEM, cell wall
Keyword [sv]
komprimering, densifiering, trä, furu, hårdgöring, cellvägg, ESEM
National Category
Wood Science
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
URN: urn:nbn:se:lnu:diva-21704ISRN: KTH/TRÄ/R-98/35--SEOAI: oai:DiVA.org:lnu-21704DiVA: diva2:553074
Available from: 2012-09-24 Created: 2012-09-18 Last updated: 2012-09-24Bibliographically approved

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