20.500.12556/RUL-163140 Simulacija toplotne modifikacije jelke s spremljanjem sprememb v njenih lastnostih Simulation of the thermal modification of fir wood and the associated changes in its properties Toplotna modifikacija je ena izmed metod, pri kateri s segrevanjem v odsotnosti kisika lesu izboljšamo lastnosti in podaljšamo trajnost. Termična razgradnja lesu spremeni zgradbo celične stene, to pa močno vpliva na njegove lastnosti. Izbrali smo drevesno vrsto jelka, ki smo jo izpostavili temperaturam 170 °C, 180 °C, 190 °C, 200 °C, 210 °C ter 220 °C. Toplotno modificirane vzorce smo analizirali s termogravimetrijo v temperaturnem območju od 25 °C do 600 °C v pretoku dušika. Na podlagi rezultatov analize smo skonstruirali umeritvene krivulje za več izbranih temperaturnih območij, ki prikazujejo izgubo mase med TG meritvijo v odvisnosti od izgube mase med toplotno modifikacijo. Te bi nam lahko služile za določevanje stopnje termične modifikacije neznanih vzorcev. Najvišji korelacijski koeficient ima umeritvena premica v temperaturnem območju med 130 °C in 320 °C, ki se je izkazala za optimalno. Izvedli smo tudi FTIR analizo toplotno nemodificiranega vzorca ter vzorca, modificiranega pri 210 °C. Spektri so bili posneti v območju med 400–4000 cm$^{−1}$. Rezultati so pokazali značilne vrhove za kemijsko strukturo lesa. Vrhovi so bolj intenzivni pri vzorcu, ki ni bil predhodno toplotno modificiran. Izvedli smo tudi meritev kontaktnega kota vodne kapljice na vseh toplotno modificiranih vzorcih jelke. Rezultati so pokazali, da se kontaktni kot vodne kapljice znatno povečuje z naraščajočo stopnjo toplotne modifikacije, kar kaže na povečanje hidrofobnosti površine. Thermal modification is one of the methods used to improve the properties of wood and extend its durability. It is based on exposing the wood to elevated temperatures in the absence of oxygen. Thermal modification changes the structure of the wood's cell wall, which greatly influences its properties. We selected fir wood that we exposed to temperatures of 170 °C, 180 °C, 190 °C, 200 °C, 210 °C and 220 °C. The thermally modified samples were analysed using thermogravimetry in the temperature range between 25 °C and 600 °C in a nitrogen flow. Based on the analysis results, we constructed calibration curves for several selected temperature ranges. The calibration curves represent the correlation between the mass loss during TG measurement and the mass loss during thermal modification. The calibration curves can be used to determine the degree of thermal modification of unknown samples. The highest correlation coefficient showed the calibration curve for the temperature range between 130 °C and 320 °C, which turned out to be the optimal. We also performed a FTIR analysis of the thermally unmodified sample and the sample that was thermally modified at 210 °C. The spectra were measured in the range between 400 cm$^{−1}$ and 4000 cm$^{−1}$. The results showed characteristic peaks corresponding to the chemical structure of wood. The spectrum of the sample that was not previously thermally modified exhibited more intense peaks than the sample that was thermally modified. We also measured the contact angle of a water droplet for all thermally modified samples of fir wood. The results showed that the contact angles of water droplets on the wood surface increased significantly with the increased degree of thermal modification, indicating an increase in the hydrophobicity of the surface. toplotna modifikacija jelka termogravimetrija umeritvene premice thermal modification fir wood thermogravimetry calibration curves true false false Slovenski jezik Angleški jezik Diplomsko delo/naloga 2024-10-02 14:50:00 2024-10-02 14:50:02 2024-12-05 11:37:57 0000-00-00 00:00:00 2024 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 25338 217809411 Kosak_Tjasa_-_Simulacija_toplotne_modifikacije_jelke_s_spremljanjem_sprememb_v_njenih_lastnostih.pdf Kosak_Tjasa_-_Simulacija_toplotne_modifikacije_jelke_s_spremljanjem_sprememb_v_njenih_lastnostih.pdf 1 EB422A3269FF02EBE52585213CACD229 ce1afb19c6c1ded51901a292c99caa32bf2665e16a4c4911330e87da39927336 aec57f42-80bc-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=192645 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0