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Effect of artificial ageing on adhesive bonds from heat treated spruce
Kariž, Mirko (Author), Kitek Kuzman, Manja (Author), Šernek, Milan (Author)

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Abstract
One strategy for improving the treatability of refractory wood species is biological incising, and its efficiency depends on how the microorganisms modify the porous structure of the wood. Evaluation of the bioincised wood treatability on a micro-scale can thus help to better understand the treatability enhancing mechanisms. In the present study, the biodegradation pattern and micro-scale treatability of Loblolly pine (Pinus taeda L.) heartwood were determined after bioincising with the white-rot fungus Physisporinus vitreus (Pers.: Fr.) P. Karsten isolate 136 and bacterium Bacillus subtilis UTB22. Oven-dried specimens with dimensions of 50 mm × 25 mm × 15 mm (L × T × R) were incubated with the microorganisms at (23±2) °C and (65±5) % relative humidity for six weeks. The control and exposed wood blocks were then pressure treated by 1 % fluorescent dye (fluorescein)- containing water to study the treatability pattern under a fluorescence microscope. The longitudinal and tangential air permeability and compression strength parallel to the grain of the specimens were also determined at the end of the incubation period. Scanning electron microscopic (SEM) studies showed that degradation by B. subtilis UTB22 was limited to the pit membranes, but the cell walls were also degraded to some extent by P. vitreus. The fungus caused a higher mass loss compared to the bacterium, whereas the permeability enhancing ability of the bacterium was more pronounced. The fluorescent dye tracer also showed that higher treatability with more uniformity was obtained by B. subtilis UTB22. The improvement in treatability by both microorganisms was mainly due to the degradation of the earlywood tracheids

Language:English
Keywords:heat treated spruce, adhesive bond, artificial ageing, shear strength, delamination, colour change
Tipology:1.01 - Original Scientific Article
Organization:BF - Biotechnical Faculty
Year:2021
Number of pages:Str. 381-388
Numbering:Vol. 72, iss. 4
UDC:630*824.322
ISSN on article:0012-6772
DOI:10.5552/drvind.2021.2044 This link opens in a new window
COBISS.SI-ID:86849539 This link opens in a new window
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Downloads:27
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Record is a part of a journal

Title:Drvna industrija
Shortened title:Drv. ind.
Publisher:Šumarski fakultet Sveučilišta u Zagrebu, Hrvatsko šumarsko društvo, Croatiadrvo, d. d., Exportdrvo, p. o.
ISSN:0012-6772
COBISS.SI-ID:2858754 This link opens in a new window

Secondary language

Language:Croatian
Title:Utjecaj umjetnog starenja na lijepljeni spoj toplinski modificirane smrekovine
Abstract:
Jedna od metoda poboljšanog impregniranja slabo poroznih vrsta drva jest tretiranje drva mikroorganizmima, a cilj tog postupka jest promjena porozne strukture drva. Evaluacija tretmana drva mikroorganizmima može pridonijeti boljem razumijevanju mehanizama poboljšanja prodora zaštitnog sredstva u drvo. U ovom je istraživanju promatrana biorazgradnja i impregnacija srži lobodijskog bora (Pinus taeda L.) na mikrorazini nakon izloženosti drva gljivi bijele truleži Physisporinus vitreus (Pers.: Fr.) P. Karsten izolat 136 i bakteriji Bacillus subtilis UTB22. Apsolutno suhi uzorci drva dimenzija 50 mm × 25 mm × 15 mm (L × T × R) zaraženi su mikroorganizmima pri 23±2 °C i 65±5 % relativne vlažnosti zraka tijekom šest tjedana. Nakon toga kontrolni i zaraženi blokovi drva tlačnim su postupkom impregnirani fluorescentnim bojilom otopljenim u vodi (1 %-tni fluorescein) kako bi se pod fluorescentnim mikroskopom promotrio učinak tretmana drva mikroorganizmima. Na kraju inkubacije utvrđena je propusnost zraka u uzdužnom i tangentnom smjeru te izmjerena čvrstoća na tlak paralelno s vlakancima. Istraživanje pretražnim elektronskim mikroskopom (SEM) pokazalo je da je razgradnja bakterijom B. subtilis UTB22 ograničena na membrane jažica, dok su stanične stijenke u određenoj mjeri razgrađene djelovanjem gljive P. vitreus. Gljiva je uzrokovala opsežniji gubitak mase nego bakterija, dok je sposobnost bakterije da poveća propusnost bila veća. Fluorescentno bojilo također je pokazalo da je bakterijom B. subtilis UTB22 postignuta bolja propusnost, s većom ujednačenošću. Poboljšanje propusnosti primjenom obaju mikroorganizama uglavnom je posljedica razgradnje traheida ranog drva

Keywords:smrekovina, termična modifikacija, lepilni spoj, umetno staranje, sprememba barve, delaminacija

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