Naceur Ayed

Characterization of sumac (Rhus tripartitum) root barks tannin for a potential use in wood adhesives formulation

Abstract The phenolic composition of sumac root barks was studied. Colorimetric assays, FT-IR and NMR were used to examine the phenolic composition and tannins nature. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was used to examine the structure of the tannin oligomers. TGA analysis was used to study the thermal stability of sumac tannin extract. Analyzes showed that sumac root barks are rich in condensed tannins, especially procyanidin and prodelphinidin types. Flavonoid oligomers of dimers, trimers, tetramers, pentamers and hexamers kind were detected in MALDI-TOF-positive ion mode analysis. TGA analysis showed thermal stability of sumac tannins compared to other condensed tannin types and pomegranate hydrolyzable tannins.

Valorization of Tunisian Pomegranate Peel Tannins in Green Adhesives Formulation

The possible use of Tunisian pomegranate tannins in wood adhesive formulation was studied for the first time. Colorimetric tests, Fourier transformed infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were used to examine pomegranate tannins. Analysis showed that pomegranate peels are rich in hydrolyzable tannins. The Stiasny number tests showed the low reactivity of pomegranate tannin extract to formaldehyde and thus the difficulty of using it in wood adhesive formulation. Thermomechanical analysis (TMA) and strength analysis of pomegranate tannin/hexamine-based resin showed weak bonding properties.