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Chestnut hydrolysable tannins are phenolic materials that have been considered too unreactive to compete in the phenolic resin adhesives market for exterior boards for the building industry. However, an article in 1973 describing 3 years industrial application of chestnut hydrolysable tannins during the first oil crisis indicated that this was not the case. We have extended this old work by using superior phenolic resins formulations and producing phenol–formaldehyde–chestnut tannin adhesives where a substitution of up to 80% of the phenol is possible with remarkably good results. The reactions involved were clarified by13C NMR and MALDI-TOF mass spectrometry. [ABSTRACT FROM AUTHOR]

Chestnut hydrolysable tannins are phenolic materials that have been considered too unreactive to compete in the phenolic resin adhesives market for exterior boards for the building industry. However, an article in 1973 describing 3 years of industrial application of chestnut hydrolysable tannins during the first oil crisis indicated that this was not the case. This previous work has been extended by using superior phenolic resins formulations and producing phenol-formaldehyde-chestnut tannin adhesives where a substitution of up to 80% of the phenol is possible with remarkably good results. The reactions involved were clarified by 13C NMR and MALDI-TOF mass spectrometry. [ABSTRACT FROM AUTHOR]

The article presents a study that determined the structure, polymeric nature, andoligomers distribution of six types of commercial synthetic tannins (syntans) by MALDI-TOF mass spectrometry. Among the syntans examined include polycondensation oligomers of sulfonated phenol and 4,4'-dioxydiphenylsulfone with formaldehyde and sodium bisulfite and sodium salts of polycondensation oligomers of phenol and sulfonated phenol with formaldehyde and urea.

The article presents a study which examined the structures of six commercial hydrolyzable tannins, chestnut oak, tara, sumach, chinese gall and turkey gall tannins using matrix-assisted laser desorption/ionization-time-of-light (MALDI-TOF) mass spectrometry. It cited the oligomeric structures and structure distributions of these tannins. It noted that commercial tara and turkey gall tannins were mainly polygallic oligomers of up to eight gallic acid residues linked to each other in a chain.

• Chestnut heartwood tannins were located mainly in the vessel lumen and parenchymatic cells. • In shoots, a delaminated wall structure, filled by tannins, was very often observed. • In the wood of standards, tannins were more visible in intercellular voids and cell corners. • After tannin extraction the cell lumen was empty, but tannins were still present in the cell corners and intercellular voids. Tannins are an important industrial product, with chestnut being one of the most representative species for their production, due to the occurrence that the species possesses within its wood quite big amounts of hydrolysable tannins. For industry, it is quite important to know at the cellular level where tannins are located – in the cell lumen or cell wall – and the efficiency of a particular tannin extraction process. The objective of this study was to identify and locate tannins in chestnut wood by means of UMSP (UV microspectrophotometry), considering both shoots and standards in coppice stands. The analyses were also carried out in standards before and after tannin extraction according to the parameters and methodology of an industrial process. Tannins were localized mainly inside the cell lumen of parenchymatic cells and vessels, and they were visible in parts adjacent to the cell walls. In shoots, they have been found also in locations where the cell wall is degraded. In the standards, tannins with more UV absorbance were detected and evidently present in the corners of wood cells. After tannin extraction, the cell lumen was empty, but tannins, even with lower absorbance values, were still present, mainly in the cell corners. The results open up discussion on the utilization of residual wood flour as a by-product after initial tannin extraction, which could be further exploited from the overall perspective of a circular economy. [ABSTRACT FROM AUTHOR]