Impact of Steaming Mode on Chemical Characteristics and Colour of Birch Wood

Abstract

The aim of this work was to evaluate the changes of the chemical components in birch wood (Betula pendula Roth) caused by steaming with saturated steam at three temperatures—105 °C, 125 °C and 135 °C. In the samples of the original wood and wood after steaming, select chemical characteristics were determined, and wood, isolated holocellulose and Seiferts’s cellulose were analysed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The greatest changes in the birch wood characteristics were observed in steaming mode III (135 °C). The differential spectra of the birch wood samples indicated that the hemicelluloses were significantly degraded and that the dehydration reactions were able to proceed. A clear increase in both unconjugated and conjugated carbonyls was seen only in mode III. The findings also confirmed the greater sensitivity of the guaiacyl lignin contained in broadleaves to elevated steaming temperatures, as well as the course of the thermal oxidation reactions and the formation of new carboxyls in mode III. The decrease in the ratio of absorbances H 1732/2900 and H 1243/2900 demonstrated the cleavage of acyl (acetyl and formyl) groups from birch wood hemicelluloses. The qualitative and quantitative changes of the hemicelluloses and extractive substances in birch wood during steaming were well-correlated with the measured pH values and wood colour.

Physical Properties of Hydrothermally Treated Rubberwood [Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg.] in Different Buffered Media

“…Lower temperatures (160 and 180 • C) caused less color changes in pH 6, 8 and 10 compared to acidic and water media, while high temperatures (200 • C) caused the most color changes. The hydrothermal treatment changed the color of the sample significantly as the treatment temperature increased [31][32][33]. This finding was consistent with the research findings in [34].…”

Colour Stabilisation of Surface of Four Thermally Modified Woods with Saturated Water Vapour by Finishes

“…The changes in the colour of all wood species resulting from thermal modification by saturated water vapor are considered to be of a permanent nature and irreversible. The irreversibility of the changes in the colour of woods is confirmed by the differences in the lignin-carbohydrate complex of the TM wood, as well as native wood, and by the presence of monosaccharides, organic acids, and the basic structural elements of the guaiacyl-syringyl lignin in the condensate [ 1 , 4 , 5 , 6 , 7 , 8 ]. Irreversible changes in the colour of the TM wood expand the opportunities for the use of these four woods in the fields of construction-joinery, and construction art and design.…”

“…In this study, alder ( Alnus glutinosa (L.) Gaertn), European beech ( Fagus sylvatica L.), Paper birch ( Betula papyrifera Marsh), and Norway maple wood ( Acer pseudoplatanus L.) were used. Samples of 15 × 100 × 250 mm 3 (radial × tangential × longitudinal) were prepared from both TM boards and unmodified (native) boards with saturated water vapour at a 135 ± 2.5 °C temperature for 6 h. The parameters for the modification process for the selected wood species are described in more detail in the works [ 4 , 5 , 6 , 7 ]. The samples were prepared from six-month air-conditioned and sanded boards (last sand grit P 180, sanded first in the transversely and following in the longitudinal direction).…”

“…The thermal treatment of wood with saturated water vapour is traditionally used in the woodworking industry, for example, in the manufacture of furniture components with solid wood bending, lamination of veneer (laminated bending), interior tiling, and flooring. The thermally-based modification treatment is also accompanied by the chemical reactions of the cell-wall components (polysaccharides, lignin, and extractives), which cause changes in the colour of the wood [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ].…”

Color Classification and Texture Recognition System of Solid Wood Panels

“…Syafinaz [8] studied the relationship between wood color and formaldehyde emissions from plywood of seven tropical hardwood species. Anton [9] determined the chemical properties of logs and wood samples after boiling, analyzed the wood, and isolated holocellulose and Sievetz cellulose by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). It was found that the qualitative and quantitative changes in hemicellulose extracts during the cooking of birch were closely related to the measured pH value and wood color.…”