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Near-infrared spectroscopy (NIRS) allows for the rapid estimation of a wide range of wood properties. Typically, NIRS studies on wood have utilized benchtop spectrometers, but efforts to utilize NIR hyperspectral imaging to examine wood and wood products have increased. Compared to benchtop NIR systems, hyperspectral imaging has several advantages (speed, visualization of spatial variability), but the data typically have a lower signal-to-noise ratio as well as fewer wavelengths saved; thus, hyperspectral imaging systems have a larger spectral sampling interval (SSI). Furthermore, the SSI and wavelength range varies considerably among different HSI cameras. NIR-HSI systems based on indium gallium arsenide (InGaAs) detectors have a wavelength range typically from 900 to 1700 nm, while short-wave infrared hyperspectral imaging (SWIR-HSI) systems based on mercury cadmium telluride (MCT) detectors have the 'full' NIR wavelength range from 1000 to 2500 nm. These factors may influence the performance of wood property calibrations. We compared one NIR-HSI (900–1700 nm) and three SWIR-HSI (1000–2500 nm) commercially available cameras with an NIRS benchtop spectrometer (1100–2500 nm). The performance of specific gravity (SG) and stiffness (MOE) calibration models was compared with one-hundred Douglas-fir (Pseudotsuga menziesii) samples. The limited wavelength range of an NIR-HSI camera provided the best models for MOE, whereas the NIR-HSI and two SWIR-HSI cameras provided similar SG results. SWIR-HSI models heavily favored wavelengths greater than 1900 nm. [ABSTRACT FROM AUTHOR]

Various factors affect the bonding quality of elements used for timber construction. This review includes literature studies and personal experiences related to relevant technological variables defining glue bond performance in glue-laminated timber elements during their service life. The gluing of hardwood species receives special focus as it is considered by the industry to be the most challenging process for implementation. In particular, the effects of wood species, type of adhesive, glued-wood surface quality, physical and/or chemical modification of the wood, technological solutions for gluing, and varying climatic conditions during the use phase (relative humidity, temperature, air circulation, etc.) are considered. In addition, overlapping of individual influencing factors often leads to problems with bonding, thus requiring strongly integrating measurement methods (e.g. NIR spectroscopy). The causes of variations in the results when glued wood is tested using different standardized methods are discussed. A list of open research questions is provided, and problem solutions are recommended based on systematized cutting-edge knowledge. The aim of the work is to systematize the state of knowledge of wood gluing to create a basis for controlled and stable manufacturing processes. The progress of the work will be reported in further publications. [ABSTRACT FROM AUTHOR]

The overall goal of this work was to develop a prototype expert system assisting quality control and traceability of particleboard panels on the production floor. Four different types of particleboards manufactured at the laboratory scale and in industrial plants were evaluated. The material differed in terms of panel type, composition, and adhesive system. NIR spectroscopy was employed as a pioneer tool for the development of a two-level expert system suitable for classification and traceability of investigated samples. A portable, commercially available NIR spectrometer was used for nondestructive measurements of particleboard panels. Twenty-five batches of particleboards, each containing at least three independent replicas, was used for the original system development and assessment of its performance. Four alternative chemometric methods (PLS-DA, kNN, SIMCA, and SVM) were used for spectroscopic data classification. The models were developed for panel recognition at two levels differing in terms of their generality. In the first stage, four among twenty-four tested combinations resulted in 100% correct classification. Discrimination precision with PLS-DA and SVMC was high (>99%), even without any spectra preprocessing. SNV preprocessed spectra and SVMC algorithm were used at the second stage for panel batch classification. Panels manufactured by two producers were 100% correctly classified, industrial panels produced by different manufacturing plants were classified with 98.9% success, and the experimental panels manufactured in the laboratory were classified with 63.7% success. Implementation of NIR spectroscopy for wood-based product traceability and quality control may have a great impact due to the high versatility of the production and wide range of particleboards utilization. [ABSTRACT FROM AUTHOR]

The thermo-vacuum process is an alternative technology for thermal modification of wood where reduction of oxygen concentration inside the reactor, necessary to avoid wood combustion, is obtained by applying vacuum. The goal of this research was to exploit the potential of near infrared spectroscopy for the quality control of TMW (prediction of mass loss and equilibrium moisture content in both softwoods and hardwoods), exposed to the thermal treatment in vacuum conditions. Applied chemometric techniques confirm great potentiality of the near infrared spectroscopy. Important parameters characterizing quality of TMW in vacuum conditions were predicted with high accuracy. Prediction errors of chemometric models based on near infrared spectra were relatively small; 0.9% and 0.36% in case of mass loss and equilibrium moisture content respectively. Such methodology might be helpful for development of on-line process control and for further optimization of the thermal treatment procedure at industrial scale. [ABSTRACT FROM AUTHOR]

Wood is one of the oldest building materials and, thanks to its favorable mechanical and technological properties, one of the most versatile. Due to its biological nature, wooden artefacts can undergo some alteration during their service life that can be caused by mechanical, environmental or biological agents. Waterlogged and buried wood elements, present in wetlands and aquatic environments, are subject to modifications at the chemical and anatomical level, which also affect physical and related mechanical properties of the material. The possibility to predict long-term performance and the rate of modification of mechanical/physical properties of the wood material in specific environmental conditions is crucial for proper design and optimal maintenance of submerged load-bearing timber structures. Therefore, prediction models to estimate selected material properties were developed within this study. For this purpose Fourier Transform near-infrared (FT-NIR) spectroscopy and multivariate analysis based on partial least-squares (PLS) were used. The models proved to be effective to predict selected dynamic and physical parameters of waterlogged samples. However, in order to include the effect of water saturation in the material on site further research is indispensable. The possible detrimental effect on wood mechanical properties of waterlogging in differing environmental conditions is also discussed in this paper. Dynamic tests were performed on samples of two species, Quercus robur L. and Pinus sylvestris L., after 8 years of deposition in two differing sites. Additionally, the results obtained from fresh and archaeological samples were compared. No significant effects have been observed due to the depositional environment after short-term waterlogging. A more remarkable difference in the rate of the modification of dynamic and physical (density) properties can be attributed to differing natural features of the tested wooden species. It may be concluded that, in order to ensure a longer service-life of waterlogged timber structures, original wooden material should be properly selected, with regard to species, growth conditions, and log characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Feasibility of a portable NIR sensor for determination of wood quality aspects was demonstrated. • The best performance was obtained for prediction of moisture, density and mechanical properties. • NIR was capable of classifying defects, trace raw resources and predicting delamination. • Suggestions for industrial integration in glue-laminated timber production were provided. The feasibility of a portable NIR sensor for off-line determination of diverse wood quality aspects relevant in the production of glue-laminated timber was demonstrated. The best performance was noticed for assessing wood moisture content, with a lower capacity to estimate wood density and mechanical properties. NIR spectroscopy was modestly capable of predicting surface roughness. However, the traceability of the raw resources and the automatic classification of diverse wood defects were successfully demonstrated. The developed chemometric model could predict the total delamination and detailed delamination length. Finally, recommendations regarding further system development were provided with the aim of implementation and integration of the NIR measurement into glue-laminated timber production plants. [ABSTRACT FROM AUTHOR]

The floor in a building is an integral part of the interior and is usually considered as a very valuable component of decoration. The flooring style, construction, manufacturing technologies, finishing and maintenance reflects local traditions, available resources and craftsmanship. Traditional techniques of parquet surface finishing were used in manor houses of South-Eastern Poland until the 1st half of the 20th century. Unfortunately, the major part of historical wooden parquets was irreversibly destroyed due to the introduction of collective property and the expropriation of manor houses after World War II. It is necessary to develop the knowledge related to the chemical, physical and mechanical properties of antique floor heritage, for its proper conservation. Near infrared spectroscopy was applied here for rapid and non-destructive recognition of natural finishes traditionally applied for the protection of the wooden floors. The system was capable to correctly identify the reference finishes applied on contemporary wood samples. However, analyses of antiques floors were more problematic. The set of samples of original antique decorative wooden flooring was collected from manor houses in Tarnowiec and Falejówka. Both houses contained well preserved wooden flooring that had not been subject to restoration in the past. The method shows great potential, even if in some cases an ambiguous classification was obtained. The reasons included natural deteriorations of floors during service life. Originally used substances might change their chemical composition during lifetime as a result of aging, weathering, usage and external contaminations. Given that, it was concluded that the results of spectroscopic evaluations might provide valuable assistance to conservators and facilitate decisions on the proper object maintenance. [ABSTRACT FROM AUTHOR]

Refining of industrial lignin to produce homogeneous fractions is essential for high-value applications. However, the understanding of key interactions between a variety of solvents with lignin polymer is still uncertain. In this work, single-step fractionation of industrial hardwood kraft lignin (HKL) using organic solvents of different polarities – ethanol, acetone, diethyl ether and hexane – was investigated by combining an experimental and theoretical approach. Experimental results revealed that higher polarity solvents (ethanol and acetone) exhibited higher solubility yield compared to moderate and low polarity solvents. The chemical differences between lignin fractions were proven by pyrolysis gas chromatography mass spectrometry and near infrared spectroscopy. Density functional theory (DFT) results indicated that ethanol presented higher interaction energy followed by acetone, diethyl ether and hexane, which was consistent with experimental findings. Hydrogen bond and non-covalent interaction results from DFT demonstrated that the predominant interaction was found for high polarity of ethanol over other solvents and γ-OH in the lignin model is the key site. Unlabelled Image • Single-step fractionation was carried out for hardwood kraft lignin using 4 solvents. • Higher polarity solvents exhibited higher solubility yield. • Fractionation with diethyl ether leaded to homogeneous low molecular weight fraction. • Quantum chemical calculations showed that ethanol exhibited higher interaction energy. • γ-OH in the lignin model is the key site for strong hydrogen bonding. [ABSTRACT FROM AUTHOR]