Določitev stopnje toplotne modifikacije jesenovine

Rašl, Katja (author), Cerc Korošec, Romana (mentor)

Toplotna modifikacija je postopek, ki se uporablja z namenom izboljšanja lastnosti lesa (zmanjšana higroskopnost, izboljšana dimenzijska stabilnost in povečana odpornost proti lesnim škodljivcem). Zaradi dobrih mehanskih lastnosti in velike gostote jesenovega lesa smo izbrali to lesno vrsto, ki smo jo modificirali v odsotnosti kisika pri 180, 190, 200, 210 in 220 °C. Toplotno modificirane vzorce smo nato analizirali s termogravimetrijo v temperaturnem območju od 25 do 600 °C v pretoku argona in iz podatkov skonstruirali umeritvene krivulje, ki so prikazovale izgubo mase pri TG meritvi v odvisnosti od izgube mase med toplotno modifikacijo. Vse umeritvene krivulje imajo linearno odvisnost, najvišji korelacijski koeficient pa so imele v območju izgube mase od 130 do 280 °C, od 130 do 290 °C in od 130 do 300 °C. Adsorbirano vlago toplotno modificiranih vzorcev smo preverjali s postopkom navlaževanja v kontrolirani atmosferi z nadzorovano vlažnostjo. Vzorce smo navlažili v zaprtem eksikatorju, v katerem se je nahajala nasičena raztopina Mg(NO3)2 oziroma KNO3 pri 25 °C. Iz podatkov o izgubi mase med sušenjem navlaženih vzorcev in izgubi mase med toplotno modifikacijo smo spet izrisali umeritvene krivulje. Pri obeh postopkih navlaževanja je bila odvisnost eksponentna, le da je imela krivulja navlaževanja z Mg(NO3)2 višji korelacijski koeficient.

• Language: Slovenian
• Keywords: toplotna modifikacija, termogravimetrija, jesenovina
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2019
• PID: 20.500.12556/RUL-110782
• COBISS.SI-ID: 1538434243
• Publication date in RUL: 19.09.2019

Secondary language

• Language: English
• Title: Determination of thermal modification degree of ash wood

Abstract

Thermal modification is a process which is used to improve the quality of wood (reduced hygroscopicity, improved dimension stability and increased resistance to wood pests). Ash wood was selected for the process because of its good mechanical properties and high density. The wood was modified in the absence of oxygen at 180, 190, 200, 210 and 220 °C. Thermally modified samples were then analysed by thermogravimetry in the temperature range from 25 to 600 °C under argon flow. Calibration curves were constructed showing the mass loss during the TG measurement as a function of the mass loss during thermal modification. All calibration curves show a linear dependence, with the highest correlation coefficient in the range from 130 to 280 °C, 130 to 290 °C, and 130 to 300 °C. The adsorbed moisture of thermally modified samples was checked by a humidification process in a controlled atmosphere with known humidity. Samples were moistened in a closed desiccator that contained saturated solutions of either Mg(NO3)2 or KNO3. From the data of the mass loss during drying of the previously moistened samples and the mass loss during thermal modification, calibration curves were again plotted. Both calibration curves showed exponential dependence, while the calibration curve from the humidification processes with Mg(NO3)2 had a higher correlation coefficient.

• Keywords: thermal modification, thermogravimetry, ash wood