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Karakterizacija anatomske zgradbe in osnovnih fizikalnih lastnosti velenjskega ksilita
Gorišek, Željko (Author), Čufar, Katarina (Author), Straže, Aleš (Author)

URLURL - Presentation file, Visit http://eprints.gozdis.si/110/1/zbgl%2D98%2D3.pdf This link opens in a new window

Abstract
Ksilit je litotip lignita, ki ga poznamo predvsem kot kurivo. Les, iz katerega je nastal, je v obdobju skoraj dveh milijonov let doživel drastične spremembe, struktura lesa pa je delno še prepoznavna. Ksilit po videzu pogosto spominja na lesne vrste s temno jedrovino. Opravili smo karakterizacijo ksilita z vidika anatomije lesa, iz katerega je nastal, raziskali njegovo ohranjenost in določili osnovne fizikalne značilnosti. Prepoznali smo osnovno tkivo iz traheid, enoredno in homocelularno trakovno tkivo, taksodioidne piknje v križnih poljih in obilico aksialnega parenhima z vključki. To nakazuje, da je ksilit nastal iz lesa golosemenk (iglavcev) iz družine Taxodiaceae (taksodijevke) ali Cupressaceae (cipresovke). Barvnometrično je ksilit v sistemu CIELab* primerljiv z jedrovino lesa ebenovine ali wengeja. Proučeni ksilit je imel gostoto v absolutno suhem stanju 1216 kg/m3, zaradi velikega volumenskega skrčka (v povprečju 28.2 %) paje bila srednja osnovna gostota samo 873 kg/m3. Celotni linearni skrčki so veliki, kar se kot posledica kaže v neugodnih kazalnikih dimenzijske stabilnosti (qT = 0.65 %/%, qR = 0.30 %/%). Nadpovprečno visoke so tudi ravnovesne vlažnosti ksilita v procesu desorpcije, sorpcijska kapaciteta v procesu adsorpcije pa je podobna kot pri lesnih vrstah z visoko gostoto. Sorpcijski model GAB se je izkazal kot primeren za izravnavo sorpcijskih podatkov.

Language:Slovenian
Keywords:ksilit, anatomska zgradba, les, barva, gostota, sorpcija, krčenje, dimenzijska stabilnost
Work type:Scientific work (r2)
Tipology:1.01 - Original Scientific Article
Organization:BF - Biotechnical Faculty
Year:2012
Number of pages:str. 27-38
Numbering:Št. 98
UDC:630*89:630*81(045)=163.6
ISSN on article:0351-3114
COBISS.SI-ID:3581094 Link is opened in a new window
Views:1065
Downloads:147
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Record is a part of a journal

Title:Zbornik gozdarstva in lesarstva
Shortened title:Zb. gozd. lesar.
Publisher:Gozdarski inštitut Slovenije, Biotehniška fakulteta, Oddelek za gozdarstvo in obnovljive gozdne vire, Biotehniška fakulteta, Oddelek za lesarstvo
ISSN:0351-3114
COBISS.SI-ID:6206978 This link opens in a new window

Secondary language

Language:Slovenian
Abstract:
Xylite is a lithotype of lignite, mainly used for fuel. The wood from which it was formed in a long term process (duration ca. 2 millions of years) was subjected to drastic changes. We conducted anatomical characterization of xylite, evaluated preservation of wood from which it was formed, defined its basic physical properties, and compared it with modern wood. We recognized ground tissue composed of tracheids, uniseriate and homocellular rays, taxodioid like cross-field pits, and abundant axial parenchyma with inclusions. The observed features are typical of coniferous wood species of the Taxodiaceae and Cupressaceae families. Colourimetric properties of xylite in CIELab* system are comparable to those of heartwood of ebony or wenge. The xylite had high oven dry density (1,216 kg/m3), but due to very high volumetric shrinkage (28.2 % on average), its basic density was much lower (873 kg/m3). Total linear shrinkage was considerable in all anatomical directions. Consequently it was characterized by low dimensional stability (qT= 0.65 %/%, qR = 0.30 %/%). The equilibrium moisture content (EMC) in desorption process was high, and that of adsorption was comparable to EMCs of high density wood species. GAB sorption model proved to be appropriate for fitting the data obtained in the sorption process.


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