Potential use of nir and visible spectroscopy to analyze chemical properties of thermally treated wood (original) (raw)
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Assessment of the chemical change in heat treated pine wood by near infrared spectroscopy
2019
Fourier-transform near-infrared spectroscopy (FT-NIR) was used as none-destructive method to determinate changes in the chemical structure of heat-treated wood. For this purpose, pine sapwood (Pinus sylvestris L.) was treated at different temperatures (from 100 °C to 240 °C) and for three durations (1, 3 or 5 hours). The effects of chemical changes on the FT-NIR spectra are linked to absorbance changes of functional groups (–OH, –CH, –CO and –CH2) of lignin, hemicelluloses and cellulose. Gradual degradation of amorphous portion of cellulose was caused by high temperature, while crystalline and semi-crystalline portions of cellulose seem to be less affected by the thermal treatment. The effect of various intensities of heat treatment on chemical changes of wood polymers varied depending on temperature and duration. Presentation of spectra in the form of the xylograms shows clear tendency of degradation kinetic. Evaluation of thermal stability of selected wood component and/or compari...
Journal of Molecular Structure, 2011
The aim of this study is to find the most convenient procedure to make an easy differentiation between various kinds of wood. The wood samples used were: fir (Acer alba), poplar (Populus tremula), lime (Tillia cordata), sycamore (Acer pseudoplatanus), sweet cherry (Prunus avium), hornbeam (Carpinus betulus), walnut (Juglans regia), beech (Fagus sylvatica), oak (Quercus robur). The methods of investigation used were FT-IR spectroscopy, X-ray diffraction and thermogravimetry.
Chemical changes of heat treated Pine and Eucalypt wood monitored by FTIR
A hardwood, Eucalyptus globulus Labill., and a softwood Pinus pinaster Aiton., were heat treated at temperatures between 170 and 210ºC in an oven and in an autoclave. The samples were pre-extracted with dichloromethane, ethanol and water and ground prior to Fourier Transform Infrared (FTIR) spectroscopic analysis.
Quality assessment of heat-treated wood by NIR spectroscopy
Holz als Roh- und Werkstoff, 2008
NIR spectroscopy was tested for predicting the properties of heat treated wood using pine (Pinus pinaster) and eucalypt (Eucalyptus globulus) woods with two types of treatment: in oven and in a steam autoclave. Mass loss, equilibrium moisture content, dimensional stability, MOE, bending strength, colour CIELAB parameters and extractives content were determined. NIR spectra were obtained using a fibre probe on the radial surface of the samples. NIR models for mass loss showed very high coefficients of determination (R 2) for cross validation ranging from 96-98%. The models obtained for wood properties were in general good with coefficients of determination ranging from 78-95% for equilibrium moisture content, 53-78% for dimensional stability, 47-89% for MOE, 75-77% for bending strength and 84-99%, 52-96% and 66-98% for colour parameters L, a * and b * , respectively. R 2 of the models for extractive content varied between 41.9-79.8% for pine and between 35.3-82.2% for eucalypt wood. NIR spectroscopy showed a good potential for quality control and characterization of heat treated woods.
Assessing Trees, Wood and Derived Products with near Infrared Spectroscopy: Hints and Tips
Journal of Near Infrared Spectroscopy, 2016
Wood is a renewable and valuable resource for a variety of end-use application areas. However, rapid and reliable assessments are needed to identify the quality of the tree, timber or wood product at all stages of production and processing. The ideal technology for assessing wood and wood products must provide reliable data, be user-friendly, cost-competitive and provide a rapid analysis. The ultimate application of near infrared (NIR) spectroscopy of wood or wood products is to substitute for costly and time-consuming reference measurements in order to aid process optimisation or determine properties and genetic traits on large numbers of individual samples. Increased interest in the application of NIR spectroscopy in various research fields including wood is observed nowadays. A vast number of publications highlight the potential of NIR spectroscopy for the characterisation of wood in a broad area of uses. The Journal of Near Infrared Spectroscopy has published two special issues ...
NEAR INFRARED SPECTROSCOPY AS A TOOL FOR CHARACTERIZATION OF WOOD SURFACE
SYNOPSIS. The goal of this research was to exploit the potential of near infrared spectroscopy to measure and characterise various types of surfaces common in the wood/related products and to present their capabilities for application into wood research and industry. Wooden blocks originated from different countries, of various wood species and different finishes have been evaluated. Characterisation of the archaeological wood was also performed by measuring fragments of wood excavated at the site. It has been found that near infrared spectroscopy can be successfully utilized for: recognition of wood species, quantify chemical composition of wood, detection of surface finish type and monitoring of the wood/coated wood weathering. The near infrared technique could be used for analyses of archeological wood and determination of its geographical origin. Dedicated tests performed on spruce (Picea abies sp.) originated from Finland, northern Poland, southern Poland and various valleys of Italian Dolomites confirmed that it is possible to determine the wood proveniences by measuring its near infrared spectra.
Journal of Molecular Structure, 2019
In this study, the combined effects of chemical (with tricine and bicine) and thermal treatments were investigated. The modifications which appeared in the wood structure were evaluated by infrared spectroscopy and chemometric methods (principal component analysis and hierarchical cluster analysis). After the treatment, about 6e7% of WPG was identified in treated samples, but further thermal treatment decreased the WPG to about 5%. The modifications appearing in the spectra were mostly related to increase of the intensities of the bands assigned to C]O groups but also to NeH and CeN groups, with shifting of some bands to higher wavenumber values.
Infrared spectroscopy of the surface of thermally-modified teak juvenile wood
Maderas. Ciencia y tecnología
During the thermal modification of the wood there is a decreasing gradient of temperature from the surface to its interior, therefore, the most severe chemical modifications occur on the surface. These chemical modifications directly affect the quality and durability of adhesives and coating. Therefore, this study investigated the chemical modification of the surface of thermally-modified teak juvenile wood. Heartwood and sapwood samples were treated at 180 and 200ºC. Chemical analyses were performed by Fourier transform infrared spectroscopy (FTIR) in reflectance mode with a microscope. Spectra showed an increase in cellulose crystallinity and a decrease in relative contents of hydroxyl groups, lignin and extractives-especially quinones, waxes and oils-following thermal modification. Extractive content of the heartwood was relatively higher than that of sapwood. Heartwood was more susceptible to thermal degradation than sapwood.
A review of band assignments in near infrared spectra of wood and wood components
Journal of Near Infrared Spectroscopy, 2011
Near infrared (NIR) spectra of wood and wood products contain information regarding their chemical composition and molecular structure. Both influence physical properties and performance, however, at present, this information is under-utilised in research and industry. Presently NIR spectroscopy is mainly used following the explorative approach, by which the contents of chemical components and physico-chemical as well as mechanical properties of the samples of interest are determined by applying multivariate statistical methods on the spectral data. Concrete hypotheses or prior knowledge on the chemistry and structure of the sampleexceeding that of reference data-are not necessary to build such multivariate models. However, to understand the underlying chemistry, knowledge on the chemical/functional groups that absorb at distinct wavelengths is indispensable and the assignment of NIR bands is necessary. Band assignment is an interesting and important part of spectroscopy that allows conclusions to be drawn on the chemistry and physico-chemical properties of samples. To summarise current knowledge on this topic, 70 years of NIR band assignment literature for wood and wood components were reviewed. In addition, preliminary results of ongoing investigations that also led to new assignments were included for discussion. Furthermore, some basic considerations on the interactions of NIR radiation with the inhomogeneous, anisotropic and porous structure of wood, and what impact this structure has on information contained in the spectra, are presented. In addition, the influence of common data (pre)-processing methods on the position of NIR bands is discussed.