Hyperspectral Imaging Surface Analysis for Dried and Thermally Modified Wood: An Exploratory Study

Naturally seasoned, kiln-dried, and thermally modified wood has been studied by hyperspectral near-infrared imaging between 980 and 2500 nm in order to obtain spatial chemical information. Evince software was used to explore, preprocess, and analyse spectral data from image pixels and link these data to chemical information via spectral wavelength assignment. A PCA model showed that regions with high absorbance were related to extractives with phenolic groups and aliphatic hydrocarbons. The sharp wavelength band at 2135 nm was found by multivariate analysis to be useful for multivariate calibration. This peak represents the largest variation that characterizes the knot area and can be related to areas in wood rich in hydrocarbons and phenol, and it can perhaps be used for future calibration of other wood surfaces. The discriminant analysis of thermally treated wood showed the strongest differentiation between the planed and rip-cut wood surfaces and a fairly clear discrimination between the two thermal processes. The wavelength band at 2100 nm showed the greatest difference and may correspond to stretching of C=O-O of polymeric acetyl groups, but this requires confirmation by chemical analysis.

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Quality control of vacuum thermally modified wood with near infrared spectroscopy

Vacuum ◽

10.1016/j.vacuum.2014.12.027 ◽

2015 ◽

Vol 114 ◽

pp. 44-48 ◽

Cited By ~ 11

Author(s):

Anna Sandak ◽

Jakub Sandak ◽

Ottaviano Allegretti

Keyword(s):

Quality Control ◽

Infrared Spectroscopy ◽

Near Infrared Spectroscopy ◽

Near Infrared ◽

Thermally Modified Wood ◽

Modified Wood

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Colour stability of surface finishes on thermally modified beech wood

Annals of WULS, Forestry and Wood Technology ◽

10.5604/01.3001.0015.2391 ◽

2021 ◽

Vol 114 ◽

pp. 116-124

Author(s):

Gabriela Slabejová ◽

MÁRIA ŠMIDRIAKOVÁ

Keyword(s):

Surface Finish ◽

Beech Wood ◽

Surface Finishing ◽

Colour Stability ◽

Colour Difference ◽

Surface Finishes ◽

Before And After ◽

Thermally Modified Wood ◽

Wood Surfaces ◽

Modified Wood

Colour stability of surface finishes on thermally modified beech wood. The paper deals with the influence of the type of transparent surface finish on the change of colour of the surfaces of native beech wood and thermally modified wood. At the same time, the colour stability of three surface finishes on the surfaces of native and thermally modified beech wood was monitored. Beech wood was thermally modified at temperature of 125 °C for 6 hours. The thermal treatment was performed in a pressure autoclave APDZ 240, by the company Sundermann s.r.o in Banská Štiavnica. Three various types of surface finishes (synthetic, wax-oil, water-based) were applied onto the wood surfaces. The colour of the surfaces of native wood and thermally modified wood was measured in the system CIELab before and after surface finishing; the coordinates L*, a*, b*, C*ab and h*ab were measured. From the coordinates measured before and after surface finishing, the differences were calculated and then the colour difference ∆E* was calculated. Subsequently, the test specimens with the surface finishes were exposed to natural sunlight, behind glass in the interior for 60 days. The surface colour was measured at specified time of the exposure (10, 20, 30, 60 days). The results showed that the colour of the wood surfaces changed after application of the individual surface finishes; and the colour difference reached a change visible with a medium quality filter up to a high colour difference. The wax-oil surface finish caused a high colour difference on native wood and on thermally modified wood as well. On native beech wood, the lowest colour difference after exposure to sunlight was noticeable on the synthetic surface finish. On the surface of wood thermally modified, after exposure to sunlight, the lowest colour difference was noticeable on the surface with no surface finish.

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The effect of air plasma treatment at atmospheric pressure on thermally modified wood surfaces

Wood Science and Technology ◽

10.1007/s00226-016-0856-7 ◽

2016 ◽

Vol 50 (6) ◽

pp. 1227-1241 ◽

Cited By ~ 18

Author(s):

Daniela Altgen ◽

Georg Avramidis ◽

Wolfgang Viöl ◽

Carsten Mai

Keyword(s):

Plasma Treatment ◽

Atmospheric Pressure ◽

Air Plasma ◽

Thermally Modified Wood ◽

Wood Surfaces ◽

Air Plasma Treatment ◽

Modified Wood

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Use of Thermo-Modified Wood Massif in Making Parametric Exterior Furniture

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i4.36.25045 ◽

2018 ◽

Vol 7 (4.36) ◽

pp. 1112 ◽

Cited By ~ 3

Author(s):

A. R. Shaikhutdinova ◽

R. R. Safin ◽

F. V. Nazipova ◽

S. R. Mukhametzyanov

Keyword(s):

Treated Wood ◽

Thermal Modification ◽

Saturated Steam ◽

Polished Surface ◽

Duration Of Treatment ◽

Heat Treated ◽

Different Temperatures ◽

Convective Thermal ◽

Thermally Modified Wood ◽

Modified Wood

This paper proposes the use of an array of heat-treated wood of various species to make parametric furniture for the purpose of operation in the exterior, and on objects in conditions of high humidity. The dependence of change in the color range of thermowoods depending on the temperature and duration of treatment is presented. Experiments were carried out to study the biological stability of thermally modified wood treated by various technologies including: vacuum-convective thermal modification in superheated steam, convective thermal modification in high-pressure saturated steam, as well as in hydrophobic liquids, in flue gas and vacuum-conductive thermal-modifying. The degree of resistance of wood was determined, which allows to conclude that the mass losses of heat-treated specimens caused by the destructive action of fungi are significantly lower compared to untreated ones. The researchwas conducted to determine the numerical characteristics of microroughness of the polished surface of wood, thermally modified at different temperatures.

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Establishment of moisture diffusion regularities through the polymer shell of thermally modified wood

Ukrainian Journal of Forest and Wood Science ◽

10.31548/forest2021.01.005 ◽

2021 ◽

Vol 12 (1) ◽

pp. 41-47

Author(s):

Yu. V. Tsapko ◽

O. Yu. Horbachova

Keyword(s):

Dimensional Stability ◽

Experimental Studies ◽

Treated Wood ◽

Moisture Diffusion ◽

Wood Products ◽

Heating Process ◽

Polymer Shell ◽

Coating Application ◽

Thermally Modified Wood ◽

Modified Wood

An analysis of the process of thermal modification of wood, which was obtained by a controlled heating process, was done. The unique technological properties (durability, low hygroscopicity and dimensional stability) of thermomodified wood make it possible to use it in various scope. Due to the influence of temperature there are some chemical changes in the structures of the wood cell wall components (lignin, cellulose and hemicellulose). This leads to an increase in density, hardness, improved hydrophobicity (water repellency), thereby reducing their ability to absorb moisture and swell. The products absorb moisture gradually, are less prone to swelling and shrinkage, but still need the elastic coatings application. It is proved that heat-treated wood turns gray over time under the influence of sunlight, and therefore requires additional surface treatment with a coating. Additional protective substances application on the thermo-modified wood products surface promotes dimensional stability and protects against rapid weathering of the surface in open air conditions. The use of transparent coatings and oils does not protect the surface from discoloration during weathering. They are recommended for products are manufactured from thermomodified wood, which are operated away from direct sunlight and rain. The parameters of moisture penetration into wood are mathematically modeled on the basis of the moisture diffusion quasi-stationary equation through the polymer coating on the flat sample surface. The dynamics of moisture content changes in thermally modified wood by different schedules parameters has been experimentally studied. The obtained mathematical relations based on the experimental studies results make it possible to calculate the moisture diffusion coefficient in thermally modified wood in the presence of a polymer shell. It is established that the wax coating application on the surface of the product reduces the moisture diffusion process more than 10 times for surfaces treated at a temperature of 160 °C for 1 hour. That is, such products can be used on objects with high humidity.

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Quantitative prediction of moisture content distribution in acetylated wood using near-infrared hyperspectral imaging

Journal of Materials Science ◽

10.1007/s10853-021-06812-2 ◽

2022 ◽

Author(s):

Muhammad Awais ◽

Michael Altgen ◽

Mikko Mäkelä ◽

Tiina Belt ◽

Lauri Rautkari

Keyword(s):

Moisture Content ◽

Hyperspectral Imaging ◽

Near Infrared ◽

Infrared Image ◽

Moisture Distribution ◽

Quantitative Prediction ◽

Chemical Information ◽

Least Squares Regression ◽

Dynamic Vapor Sorption ◽

Wood Surfaces

AbstractThe uptake of moisture severely affects the properties of wood in service applications. Even local moisture content variations may be critical, but such variations are typically not detected by traditional methods to quantify the moisture content of the wood. In this study, we used near-infrared hyperspectral imaging to predict the moisture distribution on wood surfaces at the macroscale. A broad range of wood moisture contents were generated by controlling the acetylation degree of wood and the relative humidity during sample conditioning. Near-infrared image spectra were then measured from the surfaces of the conditioned wood samples, and a principal component analysis was applied to separate the useful chemical information from the spectral data. Moreover, a partial least squares regression model was developed to predict moisture content on the wood surfaces. The results show that hyperspectral near-infrared image regression can accurately predict the variations in moisture content across wood surfaces. In addition to sample-to-sample variation in moisture content, our results also revealed differences in the moisture content between earlywood and latewood in acetylated wood. This was in line with our recent studies where we found that thin-walled earlywood cells are acetylated faster than the thicker latewood cells, which decreases the moisture uptake during the conditioning. Dynamic vapor sorption isotherms validated the differences in moisture content within earlywood and latewood cells. Overall, our results demonstrate the capabilities of hyperspectral imaging for process analytics in the modern wood industry. Graphical abstract

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A Brief Review of near Infrared in Petroleum Product Analysis

Journal of Near Infrared Spectroscopy ◽

10.1255/jnirs.77 ◽

1996 ◽

Vol 4 (1) ◽

pp. 69-74 ◽

Cited By ~ 25

Author(s):

Jerome Workman

Keyword(s):

Functional Groups ◽

Petroleum Product ◽

Octane Number ◽

Near Infrared ◽

Scientific Literature ◽

Multivariate Calibration ◽

Nir Spectroscopy ◽

Hydrocarbon Fuel ◽

Chemical Information ◽

Product Analysis

The use of infrared spectroscopy [including near infrared (NIR) spectroscopy] for the analysis of petroleum product analysis has become an essential component of hydrocarbon processing and refining since the mid-1940s. Early scientific literature identified absorption band positions for a variety of hydrocarbon functional groups from pure compounds to complex mixtures. The short wavelength NIR region (generally designated as 750–1100 nm), and the long-wavelength NIR region (1100–2500 nm) have been explored for their relative chemical information content with respect to hydrocarbon fuel mixtures. The functional groups of methyl, methylene, carbon–carbon, carbon–oxygen (including carbonyl), and aromatic (C–H) are measured directly using NIR spectroscopy. NIR spectroscopy combined with multivariate calibration has resulted in the reported analysis of numerous fuel components. The scientific literature has reported varied success for the measurement of RON (research octane number), MON (motor octane number), PON (pump octane number), cetane, cloud point, MTBE ( tert-Butyl methyl ether), RVP (Reid vapour pressure), ethanol, API, bromine number, lead, sulphur, aromatics, olefins and saturates content in such products as gasoline, diesel fuels, and jet fuels. This review paper summarises the foundational work using near-infrared for hydrocarbon fuels measurement beginning in 1938.

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Investigation of NIR spectroscopy for identifying and sorting wood with respect to species, moisture content, and weathering

10.32920/ryerson.14661045 ◽

2021 ◽

Author(s):

Ekaterina Tounis

Keyword(s):

Infrared Spectroscopy ◽

Moisture Content ◽

Near Infrared Spectroscopy ◽

Near Infrared ◽

Multivariate Calibration ◽

Surface Preparation ◽

Nir Spectroscopy ◽

Species Group ◽

Chemical Information ◽

Calibration Techniques

Near-infrared spectroscopy can characterize wood surfaces fast and without significant surface preparation. It is based on molecular overtone and combination vibrations which are typically very broad, leading to complex spectra. Multivariate calibration techniques are often employed to extract the desired chemical information. This study focused on the potential of near-infrared spectroscopy combined with partial least squares for identifying and sorting wood with respect to species and physical properties and on the effects of wood preparation and weathering on the precision of analysis. It was shown that a range of moisture content values and artificial weathering periods could be well predicted indepenedently of wood species analyzed. Species within the spruce-pine-fir species group could be predicted reasonably well when tested under similar conditions. When different moisture contents and weathering exposure periods were introduced, species prediction was still possible, but, with decreased prediciton ability.

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Using Fourier Transform Near-Infrared Spectroscopy to Predict the Mechanical Properties of Thermally Modified Southern Pine Wood

Applied Spectroscopy ◽

10.1177/0003702816644453 ◽

2016 ◽

Vol 70 (10) ◽

pp. 1676-1684

Author(s):

Li Tong ◽

Wenbo Zhang

Keyword(s):

Mechanical Properties ◽

Near Infrared ◽

Nir Spectroscopy ◽

Modulus Of Rupture ◽

Coefficient Of Determination ◽

Southern Pine ◽

Pine Wood ◽

Close Relationship ◽

Thermally Modified Wood ◽

Modified Wood

This study seeks to estimate the mechanical properties of thermally modified wood (TMW) using near-infrared (NIR) spectroscopy to measure 80 samples in three-point bending tests. Near-infrared spectra collected from the transverse, radial, and tangential sections of wood, coupled with chemometric techniques, were used to predict the mechanical properties of southern pine wood, from which NIR models were constructed based on partial least squares and corresponding cross-validation. The coefficient of determination between NIR transverse section spectra, as well as two mechanical properties of wood samples, modulus of rupture (MOR) and modulus of elasticity (MOE), were above 0.92 and greater than values for other sections. Spectral data from the transverse sections were richer than data from other sections, and thus, a model based on transverse sections better predicts the mechanical properties of wood. A close relationship between the values for mechanical properties (MOE and MOR) and the NIR spectra of thermally modified southern pine wood can be demonstrated, which provides the potential to predict the mechanical properties of untreated and thermally modified wood.

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