FTIR-ATR spectroscopic analyses of changes in wood properties during particle- and fibreboard production of hard- and softwood trees

Abstract

Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy was combined with multivariate data analysis to investigate the chemical changes in wood during particle- and medium density fibreboard (MDF) production of grand fir (Abies grandis [Douglas ex D. Don] Lindl.) and European beech (Fagus sylvatica L.). The mechanical and technological properties of the novel particle- and fibreboards from beech or grand fir wood were similar to those of conventional panels from pine and spruce. This indicates that these timbers can be used as resources for wood-based panel production. Principal component analysis of FTIR spectra differentiated wood, fibres, particles, MDF, and particleboards of both species in the whole production process. Modifications in the spectra of fibres and particles suggested that cellulose properties of wood were changed during mechanical pulping. Different binders and hydrophobic additives were clearly traceable and discernable in wood composites. Samples from the same production step were clustered together, indicating high homogeneity of the raw materials, and intermediate and final products, respectively. This suggests that FTIR spectroscopy in combination with cluster analysis is a useful tool to assess product quality and can be further developed to control and optimize production processes for innovative wood-based panels.

The Influence of Nanoparticles on Fire Retardancy of Pedunculate Oak Wood

“…This mainl indicates a decrease in the number of methoxyl groups, confirming the decrease in ligni content [45,46]. The bands also decreased at 1460 cm −1 (asymmetric CH3 bending in methoxyl group in lignin), 1370 cm −1 (symmetric and asymmetric CH3 bending), 1320 cm −1 (C−O vibratio in syringyl derivatives), and 1235 cm −1 (C−O stretching vibration in xylan and syringy ring), which are associated with lignin and hemicelluloses [47][48][49][50]. Their decrease sup ports the assumption that lignin degradation is caused by the presence of an alkaline en vironment (the pH of the water glass solution used in the experiment was more than 10 In contrast to previous trends, a slight increase in the 1030 cm −1 band (C−O deformatio vibrations in cellulose) was observed (Figures 3-5).…”

“…The bands also decreased at 1460 cm −1 (asymmetric CH 3 bending in methoxyl groups in lignin), 1370 cm −1 (symmetric and asymmetric CH 3 bending), 1320 cm −1 (C−O vibration in syringyl derivatives), and 1235 cm −1 (C−O stretching vibration in xylan and syringyl ring), which are associated with lignin and hemicelluloses [47][48][49][50]. Their decrease supports the assumption that lignin degradation is caused by the presence of an alkaline environment (the pH of the water glass solution used in the experiment was more than 10).…”

Particleboards from Recycled Pallets

“…Subsequently, by comparing the absorbance ratios in the FSP and RSP particles, the crystallinity indexes of cellulose [38], i.e., the "TCI" (total crystallinity index = A1372/A2900 = 0.69-0.71) and also the "LOI" (lateral order index, or empirical crystallinity index = A1430/A898 = 1.06-1.09), were almost identical for both types of spruce particles. On the contrary, the particles from RSP had a lower absorbance at 1274 cm −1 , about 24.4% (specific for quaiacyl lignin), and at 1600 cm −1 , about 32% (belonging to aromatic skeletal vibration in lignin, and -C=O stretching [34]), as well as a partly higher absorbance at 1730 cm −1 , about 17.4% (stretch of unconjugated -C=O groups of aldehydes, ketones, carboxylic acids and esters in lignin and hemicelluloses [36,39]). Differences in these three A peaks (1274, 1600, and 1730 cm −1 ) can be attributed to more factors in recycled pallets, e.g., to a local white-rot and a long-term atmospheric oxidation.…”

“…The FTIR analyses indicated that the basic chemical composition of wood particles obtained from the FSL and RSP was almost the same (Table 1). Absorbance (A) peaks of both types of spruce particles were usually very similar, i.e., the 1334 cm −1 (specific for syringyl lignin [34]), the 1372 cm −1 (belonging to CH deformations in cellulose and hemicelluloses), the 1430 cm −1 (assigned to aromatic skeletal vibrations, and to C-H plane vibration in plane cellulose [35], the 1510 cm −1 (C=C stretching of the aromatic skeletal vibrations in lignin [36]), and the 1653 cm −1 (belonging to conjugated carbonyls -C=C-C=O [37]). Subsequently, by comparing the absorbance ratios in the FSP and RSP particles, the crystallinity indexes of cellulose [38], i.e., the "TCI" (total crystallinity index = A1372/A2900 = 0.69-0.71) and also the "LOI" (lateral order index, or empirical crystallinity index = A1430/A898 = 1.06-1.09), were almost identical for both types of spruce particles.…”

“…The FTIR analyses indicated that the basic chemical composition of wood particles obtained from the FSL and RSP was almost the same (Table 1). Absorbance (A) peaks of both types of spruce particles were usually very similar, i.e., the 1334 cm −1 (specific for syringyl lignin [34]), the 1372 cm −1 (belonging to CH deformations in cellulose and hemicelluloses), the 1430 cm −1 (assigned to aromatic skeletal vibrations, and to C-H plane vibration in plane cellulose [35], the 1510 cm −1 (C=C stretching of the aromatic skeletal vi- Theoretically, no significant effect of the type of spruce particles in PBs on their TS and WA values can be explained by a similar chemical composition (e.g., amount of amorphous and crystal cellulose; type and amount of hemicelluloses, lignin and extracts) and chemical-physical characteristics (e.g., polymerization degree of cellulose; amount, space accessibility and reactivity of hydroxyl groups) of wood substance presented in the FSL and RSP. The FTIR analyses indicated that the basic chemical composition of wood particles obtained from the FSL and RSP was almost the same (Table 1).…”