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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

  • Czech description

Classification

  • Type

    J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database

  • CEP classification

  • OECD FORD branch

    20502 - Paper and wood

Result continuities

  • Project

  • 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