Chromophores' Contribution to Color Changes of Thermally Modified Tropical Wood Species
The result's identifiers
Result code in 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>
Result on the web
<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>
Alternative languages
Result language
angličtina
Original language name
Chromophores' Contribution to Color Changes of Thermally Modified Tropical Wood Species
Original language description
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.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
20502 - Paper and wood
Result continuities
Project
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Continuities
S - Specificky vyzkum na vysokych skolach
Others
Publication year
2023
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
POLYMERS
ISSN
2073-4360
e-ISSN
2073-4360
Volume of the periodical
15
Issue of the periodical within the volume
19
Country of publishing house
CH - SWITZERLAND
Number of pages
26
Pages from-to
1-26
UT code for WoS article
001152750000001
EID of the result in the Scopus database
2-s2.0-85173836401