scholarly journals Discolouration of thermally modified wood during simulated indoor sunlight exposure

BioResources ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 434-446 ◽  
Author(s):  
Josip Miklečić ◽  
Vlatka Jirouš-Rajković ◽  
Alan Antonović ◽  
Nikola Španić
Keyword(s):  
Ftir Spectroscopy ◽  
Uv Light ◽  
Window Glass ◽  
Colour Change ◽  
Chemical Changes ◽  
Wood Discoloration ◽  
Two Component ◽  
Transparent Coatings ◽  
Thermally Modified Wood ◽  
Modified Wood

This paper deals with the effect of UV light through window glass on the changes in colour of surfaces of uncoated and clear-coated thermally modified wood, and on chemical changes of surfaces of uncoated thermally modified and unmodified wood. Discoloration of the uncoated wood samples and those treated with three commercial transparent coatings (two-component polyurethane varnish, water-borne varnish, and nano-impregnation) was measured spectrophotometrically using CIELAB parameters (L*, a*, b* and DE*). FTIR spectroscopy was used to study chemical changes caused by UV irradiation. Colour change (DE*) was recorded in all tested wood samples after exposure to UV light, and the smallest discoloration was recorded in wood samples coated with two-component polyurethane varnish. FTIR spectroscopy results show that thermal treatment and exposure to UV light modified the chemical structure of wood surface and that the thermally modified samples exposed to UV light showed similar changes as unmodified samples exposed to UV light, but less pronounced.

scholarly journals Effect of Water Leaching on Photodegraded Scots Pine and Spruce Timbers Monitored by FTIR Spectroscopy

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 833
Author(s):  
Edina Preklet ◽  
László Tolvaj ◽  
Eszter Visi-Rajczi ◽  
Tamás Hofmann
Keyword(s):  
Ftir Spectroscopy ◽  
Scots Pine ◽  
Uv Irradiation ◽  
Chemical Elements ◽  
Uv Light ◽  
Carbonyl Groups ◽  
Water Leaching ◽  
Absorption Bands ◽  
Chemical Changes ◽  
Absorption Increase

The goal of this research was the systematic study and comparison of the divided individual effects of UV light irradiation and water leaching during artificial weathering. Spruce (Picea abies Karst.) and Scots pine (Pinus sylvestris L.) samples were irradiated by ultraviolet (UV) light. Another sequence of samples was treated with the combination of UV irradiation and water leaching. The total extent of UV treatment was 20 days for both series of samples. Time relation of UV irradiation and water leaching was 2:1. The chemical changes were observed by FTIR spectroscopy. The difference spectrum was used for determination of the chemical changes. Degradation of lignin was greater for the leached samples than for the pure UV treated samples. Scots pine suffered greater lignin degradation than spruce, and produced higher absorption increase on the absorption region of unconjugated carbonyls. The unconjugated carbonyl groups were the most responsive chemical elements to leaching. Spruce was more susceptible to leaching of unconjugated carbonyl groups than Scots pine. Two absorption bands of unconjugated carbonyl groups at 1706 and 1764 cm−1 wavenumbers were produced by photodegradation. The absorption band at 1764 cm−1 was more sensitive to water leaching than the band at 1706 cm−1.

scholarly journals Flammability Characteristics of Thermally Modified Meranti Wood Treated with Natural and Synthetic Fire Retardants

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2160
Author(s):  
Milan Gaff ◽  
Hana Čekovská ◽  
Jiří Bouček ◽  
Danica Kačíková ◽  
Ivan Kubovský ◽  
...  
Keyword(s):  
Burning Rate ◽  
Flame Retardants ◽  
Thermal Modification ◽  
Positive Contribution ◽  
Spearman Correlation ◽  
Chemical Changes ◽  
Combustion Properties ◽  
Flammability Characteristics ◽  
Thermally Modified Wood ◽  
Modified Wood

This paper deals with the effect of synthetic and natural flame retardants on flammability characteristics and chemical changes in thermally treated meranti wood (Shorea spp.). The basic chemical composition (extractives, lignin, holocellulose, cellulose, and hemicelluloses) was evaluated to clarify the relationships of temperature modifications (160 °C, 180 °C, and 210 °C) and incineration for 600 s. Weight loss, burning speed, the maximum burning rate, and the time to reach the maximum burning rate were evaluated. Relationships between flammable properties and chemical changes in thermally modified wood were evaluated with the Spearman correlation. The thermal modification did not confirm a positive contribution to the flammability and combustion properties of meranti wood. The effect of the synthetic retardant on all combustion properties was significantly higher compared to that of the natural retardant.

Hygroscopic properties of thermally modified false Iroko [Antiaris toxicara (Lesch)]

2021 ◽  
Vol 18 (1) ◽  
pp. 51-57
Author(s):  
F.A. Faruwa ◽  
K. Duru
Keyword(s):  
Weight Loss ◽  
Dimensional Stability ◽  
Thermal Process ◽  
Colour Change ◽  
Wood Properties ◽  
Thermal Modification ◽  
Hygroscopic Properties ◽  
Different Temperatures ◽  
Thermally Modified Wood ◽  
Modified Wood

The study investigated the use of thermal modification to improve the hygroscopic properties of False Iroko [Antiaris toxicaria (Lesch)]. Samples of Antiaris toxicara Lesch wood were subjected to thermal modification in a furnace at temperatures of 160, 180 and 200°C for 30 and 60 minutes. Results showed that wood properties were improved with exposure to different temperatures. Subsequent to the thermal process, a colour change from pale yellow to darkish brown was observed progressively with increase in temperature, accompanied by a weight loss in the range of 12.08% to 23.67%. The outcome of these treatments resulted in a decrease in volumetric swelling and increase in dimensional stability of modified wood; this can be attributed to observed decrease in moisture intake. The thermal modification of Antiaris toxicara Lesch wood affected the dimensional stability properties. Thus, due to significant changes via modification carried out on the selected species which is classified as lesser utilized wood species, lesser utilized wood,Antiaristoxicara Lesch wood is recommended for use due to its efficient dimensional stability after modification . keywords:, Thermally modified wood ;False Iroko

scholarly journals INVESTIGATION OF CHEMICAL CHANGES IN THE STRUCTURE OF THERMALLY MODIFIED WOOD

2010 ◽  
Vol 12 (2) ◽  
Author(s):  
P Niemz ◽  
T Hofmann ◽  
T Rétfalv
Keyword(s):  
Chemical Changes ◽  
Thermally Modified Wood ◽  
Modified Wood

Prediction of Colour Change of Thermally Modified Wood by near Infrared Spectroscopy

2016 ◽  
Vol 24 (6) ◽  
pp. 563-569 ◽  
Author(s):  
Li Tong ◽  
Wenbo Zhang ◽  
Wei Lu
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Colour Change ◽  
Measurement Instrument ◽  
Nir Spectroscopy ◽  
Online Quality Control ◽  
Close Relationship ◽  
Thermally Modified Wood ◽  
Modified Wood

Colour changes of untreated and thermally modified (120°C, 180°C and 220°C) southern pine wood are predicted by near infrared spectroscopy (NIR). Colour change information originating from thermal chemical decomposition was assessed by NIR spectroscopy while wood surface colour change values in the CIE1976 L*a*b* system were determined with a colour measurement instrument. Calibration models were built using partial least squares and corresponding cross-validation. A close relationship between colour change values and NIR spectra of thermally modified wood allowed for easy clustering. The proposed colour prediction model for thermally modified wood produced very high R2 values (above 0.90) and was well suited to NIR spectra acquired from wood tangential surfaces, suggesting that the method can provide effective, online quality control.

scholarly journals Photodegradation of Unmodified and Thermally Modified Wood Due to Indoor Lighting

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1060
Author(s):  
Dace Cirule ◽  
Edgars Kuka ◽  
Matiss Kevers ◽  
Ingeborga Andersone ◽  
Bruno Andersons
Keyword(s):  
Uv Radiation ◽  
Window Glass ◽  
Colour Change ◽  
Ftir Spectra ◽  
Water Soluble ◽  
Sufficient Energy ◽  
Thermally Modified Wood ◽  
Photo Stability ◽  
Indoor Lighting ◽  
Soluble Components

Considering interior applications, sunlight, both direct through open window and through window glass, and artificial lighting are the main sources of radiation possessing sufficient energy to trigger photodegradation processes in wood. LED lamps, which emit mostly visible light, are becoming the dominant artificial light source in various interiors. In the present study, photodegradation of thermally modified (TM) and unmodified (UM) ash (Fraxinus excelsior), aspen (Populus tremula), and pine (Pinus sylvestris) due to exposure to UV radiation and LED lamps was evaluated and compared by analysing wood discolouration (CIELAB colour space), changes in reflectance and FTIR spectra, and formation of water-soluble components. The results show that, apart from UV radiation, LED lamps may cause considerable photodegradation of both TM and UM wood resulting in visually perceptible colour change, alteration in chemical structure and formation of water-soluble components. Improved photo-stability was observed for TM wood exposed to UV radiation, while even more changes in FTIR spectra were detected for TM than UM wood in the experiment with LED lamps. Comparing TM and UM wood, the changes due to photodegradation were quite similar for TM wood of all species while significant differences were observed in the case of UM wood.

scholarly journals Disparity in Discolouration of Thermally Modified Wood Exposed to Solar and Artificial Ultraviolet Irradiation

2015 ◽  
Vol 34 (329) ◽  
pp. 12-20
Author(s):  
Dace Cirule ◽  
Edgars Kuka ◽  
Andis Antons
Keyword(s):  
Uv Irradiation ◽  
Colour Change ◽  
Solar Irradiation ◽  
Chemical Transformations ◽  
Uv Spectrum ◽  
Colour Parameter ◽  
Colour Parameters ◽  
Thermally Modified Wood ◽  
Artificial Uv ◽  
Modified Wood

Abstract Artificial weathering is a widely used method for predicting wood behaviour during its service life. A study was carried out to compare the colour change of thermally modified aspen (Populus tremula L.) and grey alder (Alnus incana (L.) Moench) wood during natural solar and artificial ultra violet (UV) irradiation. Thermally modified wood specimens were exposed for 30 h to artificial UV irradiation at two different intensities, i.e.1.36 W m−2 at 340 nm and 0.68 W m−2 at 340 nm, as well as to solar irradiation outdoors and indoors. After 2.5, 5 and 10 h exposure, colour parameters and reflectance spectra (360–740 nm) were determined. Colour was expressed in accordance with the CIELAB colour model as colour parameters L*, a*, b*. The total colour change ΔEab was calculated from colour parameter differences ΔL*, Δa*, Δb*. The colour changes caused by solar and artificial UV irradiation had a similar pattern for both thermally modified hardwood species under study. Changes in the individual colour parameters in the course of the experiment altered their direction, which implies that discolouration of thermally modified wood is a complicated and dynamic process with various and different chemical transformations in wood chromophores. Colour and reflectance changes had similar trends for different intensities of the same type of irradiation, but they differed for various irradiation types – natural solar or artificial UV irradiation. Greater discolouration was detected for the specimens exposed to both solar irradiations - outdoors and indoors. The results suggest that the fluorescent lamps of the UVA-340 type, which only imitate well the sunlight UV spectrum from 290 nm to 365 nm, do not fully simulate the changes in thermally modified wood induced by solar radiation.

scholarly journals Enhancing Thermally Modified Wood Stability against Discoloration

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 81
Author(s):  
Dace Cirule ◽  
Errj Sansonetti ◽  
Ingeborga Andersone ◽  
Edgars Kuka ◽  
Bruno Andersons
Keyword(s):  
Spectral Sensitivity ◽  
Color Model ◽  
Aspen Wood ◽  
Wood Discoloration ◽  
Organic Light ◽  
Film Forming ◽  
The Stability ◽  
Thermally Modified Wood ◽  
Outdoor Weathering ◽  
Modified Wood

Thermal modification of wood has gained its niche in the production of materials that are mainly used for outdoor applications, where the stability of aesthetic appearances is very important. In the present research, spectral sensitivity to discoloration of thermally modified (TM) aspen wood was assessed and, based on these results, the possibility to delay discoloration due to weathering by non-film forming coating containing transparent iron oxides in the formulation was studied. The effect of including organic light stabilizers (UVA and HALS) in coatings as well as pretreatment with lignin stabilizer (HALS) was evaluated. Artificial and outdoor weathering was used for testing the efficiency of different coating formulations on TM wood discoloration. For color measurements and discoloration assessment, the CIELAB color model was used. Significant differences between the spectral sensitivity of unmodified and TM wood was observed by implying that different strategies could be effective for their photostabilization. From the studied concepts, the inclusion of the transparent red iron oxide into the base formulation of the non-film forming coating was found to be the most effective approach for enhancing TM wood photostability against discoloration due to weathering.

Swelling kinetics of thermally modified wood

2021 ◽  
Author(s):  
Petr Čermák ◽  
Pavlína Suchomelová ◽  
Dominik Hess
Keyword(s):  
Swelling Kinetics ◽  
Thermally Modified Wood ◽  
Kinetics Of ◽  
Modified Wood

scholarly journals Deposition of Zinc Oxide Coatings on Wood Surfaces Using the Solution Precursor Plasma Spraying Process

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 183
Author(s):  
Ghiath Jnido ◽  
Gisela Ohms ◽  
Wolfgang Viöl
Keyword(s):  
Zinc Oxide ◽  
Ftir Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Color Change ◽  
Uv Light ◽  
Beech Wood ◽  
Nitrate Solution ◽  
Ftir Spectra ◽  
Solution Precursor ◽  
Wood Surfaces

In the present work, the solution precursor plasma spray (SPPS) process was used to deposit zinc oxide (ZnO) coatings on wood surfaces using zinc nitrate solution as precursor to improve the hydrophobicity and the color stability of European beech wood under exposure to ultraviolet (UV) light. The surface morphology and topography of the wood samples and the coatings were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The formation of ZnO was detected with the help of X-ray photoelectron spectroscopy (XPS) and by Fourier transform infrared (FTIR) spectroscopy. The FTIR spectra of the coated samples showed the typical Zn–O band at 445 cm−1. According to the XPS analysis, the coatings consist of two different Zn-containing species: ZnO and Zn(OH)2. Variation of the deposition parameters showed that the most significant parameters affecting the microstructure of the coating were the solution concentration, the deposition scan speed, and carrier gas flow rate. The wettability behaviors of the coated wood were evaluated by measuring the water contact angle (WCA). The coatings that completely covered the wood substrates showed hydrophobic behaviors. UV-protection of wood surfaces after an artificial UV light irradiation was evaluated by color measurements and FTIR spectroscopy. The ZnO-coated wood surfaces were more resistant to color change during UV radiation exposure. The total color change decreased up to 60%. Additionally, the FTIR spectra showed that the wood surfaces coated with ZnO had more stability. The carbonyl groups formation and C=C-bonds consumption were significantly lower.

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