Termična modifikacija različnih vrst lesa

diplomsko delo - visokošolski strokovni študij

Tine Veg (Author), Marko Petrič (Reviewer), Franc Pohleven (Mentor)

Abstract

S postopkom termične modifikacije lesu povečamo dimenzijsko stabilnost, obenem mu poslabšamo mehanske lastnosti in spremenimo barvo. Spremembe so zelo odvisne od temperature modifikacije. Postopek lahko uravnavamo tako, da s pomočjo parametrov modifikacije (temperature in časa) dosežemo želeno stopnjo spremembe strukture celične stene. Izbira vrednosti omenjenih parametrov se razlikuje glede na vrsto lesa. Termično smo modificirali 6 domačih drevesnih vrst: bor, smreko, jelko, kostanj, gaber in bukev. Polovico smo jih termično modificirali pri temperaturah 150 °C, 170 °C, 190 °C in 210 °C, ugotavljali izgubo mase in spremembo barve. Izguba mase se povišuje z naraščanjem temperature postopka, enako pa je tudi s potemnitvijo lesa; ta je zelo odvisna od drevesne vrste. Tako je npr. pri temperaturi 210 °C les gabra izgubil 16,27 % mase. Opazili smo, da pri nekaterih vzorcih že pri nižjih temperaturah prihaja do spremembe barve (170 °C). Gabrov les je potemnel za 39,7 % pri temperaturi modifikacije 210 °C. Z merjenjem barve obrušenih površin vzorcev smo ugotovili, da je notranjost lesa manj barvno spremenjena kot zunanja površina.

Keywords

les;lesne vrste;termična modifikacija;vakuum;

Data

Language:	Slovenian
Year of publishing:	2009
Source:	Ljubljana
Typology:	2.11 - Undergraduate Thesis
Organization:	UL BF - Biotechnical Faculty
Publisher:	[T. Veg]
UDC:	630*841
COBISS:	1778825
Views:	1374
Downloads:	242
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Thermal modification of different wood species
Secondary abstract:	The process of thermal modification of wood increases dimensional stability of wood. At the same time, its mechanical characteristics are decreased and its colour changed. The changes are highly dependent on the temperature of modification. The procedure can be controlled by some parameters (temperature and time) to reach the acquired degree of structural changes in wood cell walls. However, these parameters vary as regards to the type of wood. We thermally modified 6 national wood species: Scots pine, Norway spruce, fir, chestnut, hornbeam and beech. Half of them were thermally modified at temperatures of 150 °C, 170 °C, 190 °C and 210 °C. We were studying the influence of modification temperature on mass loss and a colour change. We established that the loss of mass increases with a modification temperature and at the same time, the wood darkens. Darkening of wood during modification very much depends on of wood species. At a temperature of 210 °C mass loss of hornbeam wood reached 16.27 %. We also established, that at some species, the change of colour occurs at lower temperatures (170 °C), whilst the hornbeam darkens for 39.7 % at 210 °C. With colour measurements of sanded surfaces we established that the interior of wood exhibited lower colour changes than the wood's surfaces.
Secondary keywords:	wood;wood species;thermal modification;vacuum;
Type (COBISS):	Undergraduate thesis
Thesis comment:	Univ. v Ljubljani, Biotehniška fakulteta, Odd. za lesarstvo
Pages:	IX, 32 f., [15] f. pril.
Keywords (UDC):	applied sciences;medicine;technology;uporabne znanosti;medicina;tehnika;agriculture and related sciences and techniques;forestry;farming;wildlife exploitation;kmetijstvo ter sorodne vede in tehnologije;forestry;gozdarstvo;forest products and their utilization;gozdni proizvodi in njihova uporaba;
ID:	21751