Chemical Characterization of Wood-Leather Panels by Means of 13C NMR Spectroscopy

Abstract

a Intelligent resource usage is one of the most challenging tasks for the wood-based panels industry. With respect to this issue, leather shavings, derived during leather preparation, are a promising new raw material, as they offer not only high availability, but also potentially enhance material properties such as panel fire retardancy. In order to improve the performance of these emerging panel binder materials, an understanding of chemical interactions between the different constituents is crucial. This paper investigates the chemical changes that occur during hot-pressing of wood and leather in combination with lignin by means of solid state 13 C NMR spectroscopy. These constituents, their binary mixtures, and the influences of panel pressing temperature and pressure commonly used in panel production were investigated. The study showed characteristic chemistry and features of these constituents, quantifying the impacts of both heat and pressure on their interactions. Primarily, analysis revealed that lignin readily connects with both the wood and leather components. Lignin induces chemical change within the protein structure of leather, resembling tanning reactions, or protein complexation. By analogy, it was deduced that this interaction also takes place between leather and the lignin-rich wood fibre surface. This effect may be beneficial in industrial-scale production through improving resin binding properties during panel consolidation.

Revealing the Interface Structure and Bonding Mechanism of Coupling Agent Treated WPC

“…Figure 3 shows the comparison of the NMR spectra of untreated and treated WPC. The wood component in the composites was characterised by the spectral signals of cellulose ( Figure 4 ) at 105.74 ppm for C1, 89.30 ppm, and 84.15 ppm for C4 of crystalline and amorphous cellulose respectively, 74.76 ppm and 72.49 ppm for C2,3,5, 65.02 ppm and 63.04 ppm for C6 of crystalline and amorphous cellulose respectively [ 22 , 23 , 24 , 25 , 26 , 27 ]. The diagnostic signals of hemicellulose should be at around 105 ppm (C1), 84 ppm (C4), 72–75 ppm (C2,3,5), and 65 ppm (C5), which had all overlapped with the more intense signals of cellulose due to their chemical similarities [ 23 , 26 ].…”

Lignin-based Foams: Production Process and Characterization

“…More sustainable organic alternatives, including celluloses, natural wool, and expanded cork, are already available on the market (Sen et al 2012;Zach et al 2012), and other very valuable alternatives, based on bark, straw, and wood-leather composites have been thoroughly investigated and the results are very promising (Pires et al 2010;Grünewald et al 2013;Kain et al 2014;Tondi et al 2015a).…”

Impact of Leather on the Fire Resistance of Leather-Wood Fibreboard: FT-IR Spectroscopy and Pyrolysis-GC-MS Investigation

“…A broad set of fibreboards with different amounts of leather and wood were tested to analyze the influence of the leather on mechanical strengths (e.g., bending strength and internal bond) [18][19][20]. Chemical characterization of these products was also performed with several techniques like 13 C-NMR, Raman, FT-IR, and FT-NIR spectroscopy [21][22][23][24].…”