20.500.12556/RUL-103296 Alternativne metode za vrednotenje kakovosti termično modificiranega lesa Alternative methods for quality assesment of thermally modified wood 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). 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). modifikacija lesa/termična modifikacija/gostota lesa/sorpcijske lastnosti/ kontrola kakovosti modification of wood/thermal modification/wood density/sorption properties/quality control true false false [R. Repič] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2018-09-15 07:47:20 2018-09-15 07:47:21 2022-08-16 03:41:12 0000-00-00 00:00:00 2018 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 630*84 156306 2946953 4103.pdf 4103.pdf 1 9D55D087CED9E922936130827F5D2043 8f7ced0b65aa3ae9f1a49e6d5fc6543435415a04bbea048a8f320552fcaa6287 c49d14cb-a1b5-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=113709 Biotehniška fakulteta 0 0 0