Hyperspectral Near-Infrared Image Assessment of Surface-Acetylated Solid Wood

Awais, Muhammad; Altgen, Michael; Mäkelä, Mikko; Altgen, Daniela; Rautkari, Lauri

doi:10.1021/acsabm.0c00626

Cited by 15 publications

(12 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This indicates that the rate of acetic anhydride diffusion into the cell walls of earlywood and latewood was similar, but since earlywood has thinner cell walls than latewood, a higher proportion of earlywood cell walls was acetylated compared to latewood cell walls when subjected to the same treatment time. This has also been observed in recent studies (Awais et al 2020;Mäkelä et al 2021). Consequently, for interface modification of the highest degree, the diffusion fronts from adjacent earlywood cells often reached all the way to their common middle lamella, leading to its acetylation (Fig.…”

Section: Discussionsupporting

confidence: 83%

Targeted acetylation of wood: a tool for tuning wood-water interactions

et al. 2021

View full text Add to dashboard Cite

Wood is an increasingly important material in the sustainable transition of societies worldwide. The performance of wood in structures is intimately tied to the presence of moisture in the material, which directly affects important characteristics such as dimensions and mechanical properties, and indirectly its susceptibility to fungal decomposition. By chemical modification, the durability of wood in outdoor environments can be improved by reducing the amount of moisture present. In this study, we refined a well-known chemical modification with acetic anhydride and showed how the spatial distribution of the modification of Norway spruce (Picea abies (L.) Karst.) could be controlled with the aim of altering the wood-water interactions differently in different parts of the wood structure. By controlling the reaction conditions of the acetylation it was possible to acetylate only the cell wall-lumen interface, or uniformly modify the whole cell wall to different degrees. The spatial distribution of the acetylation was visualised by confocal Raman microspectroscopy. The results showed that by this targeted acetylation procedure it was possible to independently alter the wood-water interactions in and outside of cell walls. The cell wall-lumen interface modification altered the interaction between the wood and the water in cell lumina without affecting the interaction with water in cell walls while the uniform modification affected both. This opens up a novel path for studying wood-water interactions in very moist environments and how moisture distribution within the wood affects its susceptibility towards fungal decomposition. Graphic abstract

show abstract

Section: Discussionsupporting

confidence: 83%

Targeted acetylation of wood: a tool for tuning wood-water interactions

et al. 2021

View full text Add to dashboard Cite

show abstract

“…We have recently observed similar differences in the acetylation rate of earlywood and latewood when the acetylation was initiated after a confined, onesided flow of acetic anhydride into the wood [22]. However, earlier studies in the wood field, in which wood samples were completely soaked in acetic anhydride prior to acetylation, have found little to no difference in the WPGs of earlywood and latewood.…”

Section: Discussionmentioning

confidence: 70%

“…We have recently shown that hyperspectral NIR imaging and image regression can successfully determine the penetration of acetic anhydride into the wood structure after wood acetylation [22]. Our method was based on calibrating NIR images with external WPG values measured from dried samples after confined one-sided acetylation of solid wood.…”

Section: Graphical Abstract Introductionmentioning

confidence: 99%

Hyperspectral imaging and chemometrics reveal wood acetylation on different spatial scales

et al. 2020

Self Cite

View full text Add to dashboard Cite

Acetylation is a chemical treatment method commonly used to improve the hygroscopic properties of wood. Although acetylation has been industrially used for decades, its effects on the different hierarchical structures of wood are still poorly understood. In the laboratory, acetylation is generally measured gravimetrically. Weighing a sample before and after the modification procedure provides an indirect measure of the degree of acetylation within the entire sample but does not provide detailed information on the different structural regions of wood. Here, we determined acetylation of wood surfaces using hyperspectral near-infrared image regression. Our results show significant differences in the acetylation of earlywood and latewood, which suggests different durations for complete acetylation of earlywood and latewood cells. We have also illustrated our findings on the wood cell level based on the chemical differences in earlywood and latewood cell walls using cluster analysis of Raman images. These findings are an important step in understanding how chemical treatment affects the different hierarchical structures of wood on different spatial scales. Graphical Abstract

show abstract

“…Standard normal variate scaled the data with mean zero and unit standard deviation in a rowwise fashion. Principal component analysis was performed on mosaic following singular value decomposition [12,31] algorithm. Principal components explaining the maximum variation within the data were chosen, and score vectors were reshaped back to image dimensions.…”

Section: Image Calibration and Transformationmentioning

confidence: 99%

“…In this regard, hyperspectral near-infrared (NIR) imaging is an appropriate method to study structural and chemical changes within the wood [10][11][12]. The NIR images are three-way datasets, where two dimensions render the spatial mapping of the chemical analytes, while the third dimension contains spectral variables.…”

Section: Graphical Abstract Introductionmentioning

confidence: 99%

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

et al. 2022

Self Cite

View full text Add to dashboard Cite

The 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

show abstract

Hyperspectral Near-Infrared Image Assessment of Surface-Acetylated Solid Wood

Cited by 15 publications

References 38 publications

Targeted acetylation of wood: a tool for tuning wood-water interactions

Targeted acetylation of wood: a tool for tuning wood-water interactions

Hyperspectral imaging and chemometrics reveal wood acetylation on different spatial scales

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

Contact Info

Product

Resources

About