A review of near-infrared spectroscopy for monitoring moisture content and density of solid wood

Abstract

This review article examines past and current research on the application of near-infrared (NIR) reflectance/transmittance spectroscopy (NIRS) for real-time monitoring of moisture content and density of solid wood. Most of the applications of NIRS on solid wood have focussed on the application of multivariate statistics as exploratory tools for the prediction of physical, chemical and mechanical properties, such as moisture content, density, stiffness, cellulose and lignin content. However, very few studies on the development of optical models and the use of NIRS transmittance techniques on solid wood have been reported. NIRS technology has the potential to be used as a rapid tool that could be employed for at-line measurement and monitoring of wood properties in the forest products industry.Keywords: wood properties, near-infrared spectroscopy, multivariate statistics, optical model, transmittance, reflectance résumé Cet article de revue examine la recherche passée et actuelle sur l'application de la spectroscopie proche infra-rouge en mode réflectance/transmittance pour le suivi en temps réel de la teneur en eau et de la densité du bois solide. La plupart des applications de la spectroscopie proche infra-rouge sur le bois solide ont porté sur l'application des méthodes statistiques multi-variées pour l' estimation des propriétés physiques, chimiques et mécaniques, telles que la teneur en eau, la densité, la dureté, le contenu en cellulose et en lignine. Cependant, peu d' études ont porté sur le développement de modèles optiques et sur l'utilisation de la spectroscopie proche infra-rouge en mode transmittance pour le bois solide. La spectroscopie proche infra-rouge a le potentiel d' être utilisée comme un outil rapide de mesure et suivi en temps réel des propriétés du bois dans l'industrie des produits forestiers.

Monitoring of moisture content and basic specific gravity in black spruce logs using a hand-held MEMS-based near-infrared spectrometer

“…As reviewed by Leblon et al (2013), most NIRS studies on wood moisture and basic specific gravity estimation were carried out on lumber and small clears. Only three studies considered logs.…”

Challenges in the use of Near Infrared Spectroscopy for improving wood quality: A review

“…The moisture variation has an important influence on wood properties and performance, affecting strength, drying, processing, glue curing, and bond performance (Adedipe & Dawson-Andoh, 2008). As pointed out by Leblon et al (2013), wood industry has particular interest for models capable of handling a broader range of moisture content variations in order to be able to measure MC at different steps of the manufacturing process, whatever the level of MC. Thus, many studies have been developed to deal with this important issue.…”

“…Schimleck et al (2000), So et al (2004), Tsuchikawa (2007), Tsuchikawa & Schwanninger (2013) and Tsuchikawa & Kobori (2015) presented complete review papers on NIR spectroscopy applications in wood research where recent technical and scientific reports have been widely presented and discussed. Leblon et al (2013) listed the researches on NIR spectroscopy for real-time monitoring specifically moisture content and wood density. In regard to the NIR spectra and regression coefficients interpretations, a complete discussion about the band assignments for wood and wood components has been presented by Schwanninger et al (2011).…”

Determination of Heat-Treated Eucalyptus and Pinus Wood Properties Using Nir Spectroscopy

“…Keywords: Timber quality, nondestructive evaluation, multivariate analysis, vibrational spectroscopy moisture content (Yang et al 2017), microfibril angle of cellulose deposition in wood cell wall (Hein et al 2010), wood chemical composition (Leblon et al 2013), physical and mechanical properties (McLean et al 2014, Todorovic et al 2015 and wood genetic parameters (Hein & Chaix 2014). There are studies reporting the use of NIR spectroscopy associated with multivariate analyses for predicting heat-treated wood properties (Tsuchikawa & Kobori 2015).…”

“…NIR spectroscopy has shown promising results for predicting wood moisture (Leblon et al 2013). NIR-based models for moisture of Fagus sylvatica and Pinus sylvestris wood without heat treatment had R²cv = 0.98 and 0.99 respectively (Kobori et al 2013), while models for estimating moisture of heat-treated wood of Pinus pinaster and Eucalyptus (Esteves & Pereira 2008).…”