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.