CHEMICAL ALTERATIONS OF HARDWOOD VENEERS DUE TO THERMAL TREATMENT
DOI:
https://doi.org/10.17770/etr2019vol1.4147Keywords:
FTIR, termovuoto, veneers, WTTAbstract
Wood is the most popular building material in the world due to its universal versatility, although it has disadvantages - the difficulty to apply small diameter logs in construction, hygroscopicity and anisotropic swelling and shrinking. To solve these disadvantages, plywood from wood material is produced. Plywood is a material that can solve anisotropy, but it is still biodegradable by rot and stain fungi. Thermal treatment is a methodology that improves the durability of wood. In this paper aspen (Populus tremula L.), poplar (Populus x canadensis Moench) and birch (Betula pendula Roth) were treated by steam (WTT) and vacuum (TERMOVUOTO) devices under 160°C/50 min (birch and aspen), 204°C/2 h, 214°C/2 h, 217°C/3 h, 218°C/30 min (birch and poplar). Chemical changes in treated veneers were investigated by ATR-FTIR (Attenuated Total Reflection Fourier Transform Infrared Spectroscopy) in a range 2000 cm-1 – 800 cm-1. ATR-FTIR is a non-destructive methodology, which is important during manufacturing process quality control. Untreated poplar wood and aspen wood had similar ATR-FTIR spectra because both species belong to Populus genus. Untreated birch wood had higher absorption intensity peak at 1740 cm-1, which indicates the C=O bond stretching in the carboxyl group depicting more acetyl groups in birch wood than in aspen/poplar. According to spectral data, birch wood, treated in TERMOVUOTO process at 200°C for 2 hours is chemically almost identical to untreated one. WTT process causes the most significant changes in the chemistry of both in aspen and birch. Therefore, regime 160°C/50 min in water vapour is more aggressive than treatments at higher temperatures and under reduced pressure. It is expected that plywood produced from WTT treated veneers will have reduced strength in comparison with TERMOVUOTO process produced ones.Downloads
References
C.A.S. Hill, “Thermal Modification of Wood,” in Wood modification - Chemical, Thermal and Other Processes, John Wiley&Sons, 2006, pp. 99–127.
A. Lovrić, V. Zdravković, R. Popadić, and G. Milić, “Properties of Plywood Boards Composed of Thermally Modified and Non-modified Poplar Veneer,” BioResources, vol. 12 (4), pp. 8581–8594, 2017.
B. F. Tjeerdsma and H. Militz, “Chemical changes in hydrothermal treated wood: FTIR analysis of combined hydrothermal and dry heat-treated wood,” Holz als Roh - und Werkst., vol. 63 (2), pp. 102–111, 2005
G. Rep, F. Pohleven, and S. Košmerl, Development of Industrial Kiln for Thermal Wood Modification by a Procedure with Initial Vacuum and Commercialisation of Modified Silvapro® Wood. European Conference on Wood Modification, September 17-18, 2012, Ljubjana, Slovenia, pp 13–20.
J. Van Acker, S. Michon, J. Van Den Bulcke, and I. De Windt, “Limited variability in biological durability of thermally modified timber using vacuum based technology,” International Research Group of Wood Preservation, p. IRG/WP 11-40567, 2011.
S. Ferrari, I. Cuccui, and O. Allegretti, “Thermo-vacuum Modification of some European Softwood and Hardwood Species Treated at Different Conditions,” BioResources, vol. 8 (1), pp. 1100–1109, Jan. 2013.
C. M. Simonescu, Application of FTIR Spetroscopy in Environmental Studies in Advanced Aspects of Spectroscopy. InTech, 2012.
R. Herrera, X. Erdocia, R. Llano-Ponte, and J. Labidi, “Characterization of hydrothermally treated wood in relation to changes on its chemical composition and physical properties,” Journal of Analytic and Applied Pyrolysis, vol. 107, pp. 256–266, May 2014
. [9] K. Srinivas and K. K. Pandey, “Photodegradation of thermally modified wood,” Journal of Photochemistry and Photobiology B: Biology, vol. 117, pp. 140–145, 2012.
A. Tarmian and A. Mastouri, “Changes in moisture exclusion efficiency and crystallinity of thermally modified wood with aging,” iForest - Biogeosciences and Forestry, vol. 12 (1), pp. 92–97, 2019.
J. Grinins et al., “Thermo-hydro treated (THT) birch veneers for producing plywood with improved properties,” Holzforschung, vol. 70 (8), Jan. 2016.
A. Sandak et al., Thermal modification of poplar veneers in vacuum conditions,”European Conference on Wood Modification, October 26-28, 2015, Helsinki, Finland
Y. Liu et al., “Wood Veneer Dyeing Enhancement by Ultrasonic-assisted Treatment,” BioResources, vol. 10 (1), pp. 1198–1212, Jan. 2015.
D. Kocaefe, S. Poncsak, and Y. Boluk, “Effect of thermal treatment on the chemical composition and mechanical properties of birch and aspen,” BioResources, vol. 3 (2), pp. 517–537, Apr. 2008.
J. Coates, “Interpretation of Infrared Spectra, A Practical Approach,” Encyclopedia of Analytical Chemistry, pp. 10815–10837, 2000.
M. Kacuráková, “FT-IR study of plant cell wall model compounds: pectic polysaccharides and hemicelluloses,” Carbohydrate Polymers, vol. 43 (2), pp. 195–203, Oct. 2000.
B. S. Gupta, B. P. Jelle, and P. Rüther, FTIR Spectroscopy as a Tool to Predict Service Life of Wooden Cladding. CIB World Congress 2010 - Building a Better World, May 10-13, 2010, Salford, United Kingdom.
O. Faix, Fourier Transform Infrared Spectroscopy, Springer, Berlin, Heidelberg, 1992, pp. 233–241.
R. Bodirlau and C. A. Teaca, “Fourier transform infrared spectroscopy and thermal analysis of lignocellulose fillers treated with organic anhydrides,” Romanian Reports in Physics, vol. 54 (1–2), pp. 93–104, 2009.
A. Attia, R. Aboelenin, S. Kheder, G. Mohmed, and S. El-Shafey, “The Effect of Activation Method on the Adsorption Performance of Saw-Dust Activated Carbon,” British Journal of Applied Science and Technology vol. 7(3), pp. 302–315, Jan. 2015.
M. Veizović, A. Straže, N. Todorović, K. Čufar, M. Merela, and G. Milić, Characterization of subfossil oak wood from central Serbia using SEM and FTIR spectroscopy, Conference Living with modified wood, December 12-13, 2018, Belgrade, Serbia
D. Erçin and Y. Yürüm, “Carbonisation of fir (Abies bornmulleriana) wood in an open pyrolysis system at 50-300 °C,” Journal of. Analytic and Applied Pyrolysis, vol. 67 (1), pp. 11–22, 2003.
E. Windeisen and G. Wegener, “Behaviour of lignin during thermal treatments of wood,” Industrial. Crops and Products vol. 27 (2), pp. 157–162, 2008.
