Alternativne metode za vrednotenje kakovosti termično modificiranega lesa

Repič, Rožle (author), Humar, Miha (mentor)

Termična modifikacije lesa je postopek, pri katerem v odsotnosti atmosferskega kisika les segrevamo pri temperaturah med 180 °C in 240 °C in s tem spremenimo določene lastnosti lesa. Glavne prednosti TML (termično modificiran les) so izboljšana odpornost proti škodljivcem, nižja ravnovesna vlažnost in boljša dimenzijska stabilnost. Zaradi vedno večjega povpraševanja po TML se je pojavila potreba po enostavnem in hitrem določanju kakovosti. Smrekovino, bukovino, jesenovino in topolovino smo termično modificirali po treh različnih postopkih pri temperaturah od 180 °C do 230 °C. Primerjali smo vpliv lesne vrste, temperature in postopka modifikacije na relevantne lastnosti lesa. Vzorcem smo gravimetrično določili izgubo mase med modifikacijo, izmerili smo barvo po CIE L*a*b* sistemu, določili osnovno gostoto in gostoto celične stene, tlačno trdnost in modul elastičnosti, izmerili vrednost pH, stični kot vodne kapljice na površini spremljali smo navzem vode in vodne pare. Izguba mase je višja pri vzorcih modificiranih pri višji temperaturi, enako je s spremembo barve. Stični kot vodne kapljice je pri vzorcih modificiranih pri višji temperaturi večji. Kratkotrajni navzem skozi čelno površino vzorca pri bukovini je manjši pri višji temperaturi modifikacije, tudi ravnovesna vlažnost je nižja. Kot najbolj indikativna metoda za določanje stopnje modifikacije se je izkazala metoda DVS (dinamična sorpcija vodne pare).

• Language: Slovenian
• Keywords: modifikacija lesa/termična modifikacija/gostota lesa/sorpcijske lastnosti/ kontrola kakovosti
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [R. Repič]
• Year: 2018
• PID: 20.500.12556/RUL-103296
• UDC: 630*84
• COBISS.SI-ID: 2946953
• Publication date in RUL: 15.09.2018

REPIČ, Rožle, 2018, Alternativne metode za vrednotenje kakovosti termično modificiranega lesa [online]. Master’s thesis. R. Repič. [Accessed 31 May 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=103296

Secondary language

• Language: English
• Title: Alternative methods for quality assesment of thermally modified wood

Abstract

Thermal modification of wood is a process in which, in the absence of atmospheric oxygen, wood is heated at a elevated temperature in the range of 180 °C in 240 °C, thereby changing certain properties of the wood. Main advantages of TMW (thermally modified wood) are improved resistance to decay, lower equilibrium moisture and better dimensional stability. Due to increasing demand for TMW, the need for simple and quick quality control has emerged. Spruce wood, beech wood, ash wood and poplar wood were thermally modified according to three different processes at temperatures ranging from 180 °C to 230 °C. We compared the influence of wood species, temperature and modification process on relevant wood properties. Mass loss during modification was gravimetrically determined, colour was measured using CIE L*a*b* colour scale, »envelope« and »true« density were determined, compressive strength and modulus of elasticity were measured, pH was measured, the contact angle of water droplet on surface was monitored, so was water and water vapour uptake. Mass loss is higher for samples modified at a higher temperature and so is colour change. Contact angle is higher on samples treated at a higher temperature. Short-term absorption through end surface of the sample in beech wood is lower at a higher temperature of modification; equilibrium moisture content is lower respectively. As most indicative method for determining degree of modification has proven to be DVS (dynamic sorption of water vapour).

• Keywords: modification of wood/thermal modification/wood density/sorption properties/quality control