Moisture desorption isotherms and thermodynamic properties of two dense tropical woods: Tali (Erythrophleum suaveolens Brenan) and Bilinga (Nauclea diderrichii Merr).

Autor: Fonyuy, Banyuy Godwin, Tamba, Jean Gaston, Mfomo, Joseph Zobo, Fopah-Lele, Armand, Diboma, Benjamin Salomon, Bengono, Dominique Martial Manga, Fedoung, Evariste Fongnzossie, Biwolé, Achille Bernard
Zdroj: European Journal of Wood & Wood Products / Holz als Roh- und Werkstoff; Jun2023, Vol. 81 Issue 3, p733-745, 13p
Abstrakt: The aim of this study was to determine moisture desorption isotherms and some thermodynamic properties of two dense tropical woods from Cameroon: Tali (Erythrophleum suaveolens) and Bilinga (Nauclea diderrichii), which are classified as medium-heavy (Bilinga) and heavy (Tali) woods with high economic values. Equilibrium moisture contents (EMC) were determined using the static gravimetric method at three temperatures (30 °C, 40 °C, 60 °C) and relative humidities (RH) between 5.5 and 83.6%. For thermodynamic properties, Gibbs free energy (GFE), net isosteric heat (qst,n) and differential entropy (ΔS) were determined using Clausius Clapeyron and Avramidis equations. To interpret hygroscopic behavior and thermodynamic properties, anatomical and chemical structures were analyzed using microscopic images and infrared (IR) spectroscopy respectively. EMC decreased from 19.39 to 1.99% for Bilinga and from 11.17 to 0.51% for Tali as temperature increased. GAB model best described desorption isotherms data. Desorption isotherms recorded type II sigmoids. Anatomical analysis revealed that Tali and Bilinga had porosities of 40.52 and 50.32%, 3–6 and 6–12 vessels/mm2, 400–700 µm and 700–1000 µm rays respectively. Specific Surface Areas (SSA) decreased from 155.602 to 57.115 m2/g for Tali and 287.692 to 175.688 m2/g for Bilinga. This result supports the isotherms measurement in terms of hygroscopic capacity of woods. Positive thermodynamic properties revealed that desorption was non-spontaneous and the difference between harmonic mean and isokinetic temperatures confirms an enthalpy-entropy compensation theory. qst,n is higher for Tali implying it is less hygroscopic and requires more energy than Bilinga. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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