Chromophores' Contribution to Color Changes of Thermally Modified Tropical Wood Species

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60460709%3A41320%2F23%3A97943" target="_blank" >RIV/60460709:41320/23:97943 - isvavai.cz</a>

Výsledek na webu

<a href="https://pubmed.ncbi.nlm.nih.gov/37836049/" target="_blank" >https://pubmed.ncbi.nlm.nih.gov/37836049/</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3390/polym15194000" target="_blank" >10.3390/polym15194000</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Chromophores' Contribution to Color Changes of Thermally Modified Tropical Wood Species

Popis výsledku v původním jazyce

This work examines the effect of thermal modification temperature (180, 200, and 220 degrees C) in comparison with reference (untreated) samples on selected optical properties of six tropical wood species-Sp. cedar (Cedrala odorata), iroko (Chlorophora excelsa), merbau (Intsia spp.), meranti (Shorea spp.), padouk (Pterocarpus soyauxii), and teak (Tectona grandis). The main goal is to expand the existing knowledge in the field of wood thermal modification by understanding the related degradation mechanisms associated with the formation of chromophoric structures and, above all, to focus on the change in the content of extractive substances. For solid wood, the CIELAB color space parameters (L*, a*, b*, and Delta E*), yellowness (Y), ISO brightness, and UV-Vis diffuse reflectance spectra were obtained. Subsequently, these wood samples were extracted into three individual solvents (acetone, ethanol, and ethanol-toluene). The yields of the extracted compounds, their absorption spectra, and again L*, a*, b*, Delta E*, and Yi parameters were determined. With increasing temperatures, the samples lose brightness and darken, while their total color difference grows (except merbau). The highest yield of extractives (mainly phenolic compounds, glycosides, and dyes) from thermally modified samples was usually obtained using ethanol. New types of extractives (e.g., 2-furaldehyde, lactones, formic acid, some monomer derivatives of phenols, etc.) are already created around a temperature of 180 degrees C and may undergo condensation reactions at higher temperatures. For padouk, merbau, teak, and partially iroko modified at temperatures of 200 and 220 degrees C, there was a detected similarity in the intensities of their UV-Vis DR spectra at the wavelength regions corresponding to phenolic aldehydes, unsaturated ketones, quinones, stilbenes, and other conjugated carbonyl structures. Overall, a statistical assessment using PCA sorted the samples into five clusters. Cluster 3 consists of almost all samples modified at 200 and 220 degrees C, and in the other four, the reference and thermally modified samples at 180 degrees C were distributed. The yellowness of wood (Y) has a very high dependence (r = 0.972) on its brightness (L*) and the yellowness index of the extractives in acetone Yi(Ac), whose relationship was described by the equation Y = -0.0951 x Y(Ac) + 23.3485.

Název v anglickém jazyce

Chromophores' Contribution to Color Changes of Thermally Modified Tropical Wood Species

Popis výsledku anglicky

This work examines the effect of thermal modification temperature (180, 200, and 220 degrees C) in comparison with reference (untreated) samples on selected optical properties of six tropical wood species-Sp. cedar (Cedrala odorata), iroko (Chlorophora excelsa), merbau (Intsia spp.), meranti (Shorea spp.), padouk (Pterocarpus soyauxii), and teak (Tectona grandis). The main goal is to expand the existing knowledge in the field of wood thermal modification by understanding the related degradation mechanisms associated with the formation of chromophoric structures and, above all, to focus on the change in the content of extractive substances. For solid wood, the CIELAB color space parameters (L*, a*, b*, and Delta E*), yellowness (Y), ISO brightness, and UV-Vis diffuse reflectance spectra were obtained. Subsequently, these wood samples were extracted into three individual solvents (acetone, ethanol, and ethanol-toluene). The yields of the extracted compounds, their absorption spectra, and again L*, a*, b*, Delta E*, and Yi parameters were determined. With increasing temperatures, the samples lose brightness and darken, while their total color difference grows (except merbau). The highest yield of extractives (mainly phenolic compounds, glycosides, and dyes) from thermally modified samples was usually obtained using ethanol. New types of extractives (e.g., 2-furaldehyde, lactones, formic acid, some monomer derivatives of phenols, etc.) are already created around a temperature of 180 degrees C and may undergo condensation reactions at higher temperatures. For padouk, merbau, teak, and partially iroko modified at temperatures of 200 and 220 degrees C, there was a detected similarity in the intensities of their UV-Vis DR spectra at the wavelength regions corresponding to phenolic aldehydes, unsaturated ketones, quinones, stilbenes, and other conjugated carbonyl structures. Overall, a statistical assessment using PCA sorted the samples into five clusters. Cluster 3 consists of almost all samples modified at 200 and 220 degrees C, and in the other four, the reference and thermally modified samples at 180 degrees C were distributed. The yellowness of wood (Y) has a very high dependence (r = 0.972) on its brightness (L*) and the yellowness index of the extractives in acetone Yi(Ac), whose relationship was described by the equation Y = -0.0951 x Y(Ac) + 23.3485.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20502 - Paper and wood

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

POLYMERS

ISSN

2073-4360

e-ISSN

2073-4360

Svazek periodika

15

Číslo periodika v rámci svazku

19

Stát vydavatele periodika

CH - Švýcarská konfederace

Počet stran výsledku

26

Strana od-do

1-26

Kód UT WoS článku

001152750000001

EID výsledku v databázi Scopus

2-s2.0-85173836401