African tree bark exudate extracts as biohardeners of fully biosourced thermoset tannin adhesives for wood panels

A totally “bio” hardener derived from the exudate extract of the African trees Vachellia nilotica and Senegalia senegal was investigated. It hardened a maritime pine tannin resin without any obvious presence of an aldehyde thus obtaining a completely “bio” adhesive for wood panels. MALDI-ToF and CP MAS 13C NMR analysis indicated that the hardeners cross-linking species was 2,5-dihydroxymethyl furan linked onto carbohydrate chains. The...