https://pubs.rsc.org/en/content/articlepdf/2015/gc/c5gc00282f

Chemical modification of tannins to elaborate aromatic biobased macromolecular architectures

Tannins as a sustainable raw material for green chemistry: A review

Nitrogen-doped carbon materials produced from hydrothermally treated tannin

https://aaltodoc.aalto.fi/bitstream/handle/123456789/15348/article3.pdf?sequence=4

Spruce bark as an industrial source of condensed tannins and non-cellulosic sugars

Chemical characterisation of bark and of alkaline bark extracts from maritime pine grown in Portugal.

The phlobaphenes formation and precipation during sulphite/water extraction of pine tannins from pine bark was minimized by blocking tannin self-condensation by the addition of small amounts of a strong nucleophile such as phloroglucinol, m-phenylenediamine and urea, the latter due to its low cost for industrial application. These inhibitors reacted preferentially with the reaction intermediates formed in the tannins self-condensation mechanism, stopping the reaction reaching the molecular rearranged precipates known as phlobaphenes. The principle of inhibition appears to be effective at both the laboratory and industrial level. The results of laboratory and industrial extractions and the results of the adhesives from the modified pine tannin extract/urea adducts obtained are presented. The pine tannin/urea extracts proved to yield good thermosetting wood adhesives for panel products. The minimization of phlobaphenes precipitation increased the yield from 19% to 25% industrial scale.

V. J. Sealy-Fisher

Papers

Increased pine tannins extraction and wood adhesives development by phlobaphenes minimization