Characterization of Tunisian Aleppo pine tannins for a potential use in wood adhesive formulation

•Aleppo pine tannins were studied and characterized by different methods and techniques.•Aleppo pine barks are found to be rich in condensed tannins of procyanidins and prodelphinidins types.•Extraction of Aleppo pine tannins was optimized.•Aleppo pine tannins extract is very reactive toward formaldehyde.•Aleppo pine tannins-based adhesive shows good thermal and mechanical performances compared to commercial tannins-based adhesives. The phenolic composition of Tunisian Aleppo pine barks was studied. Colorimetric assays, Fourier transformed infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) were used to examine Aleppo pine tannins. Analyzes showed that Aleppo pine barks are rich in condensed tannins, especially in procyanidin and prodelphinidin tannins. The reactivity to formaldehyde test (Stiasny number) showed the possible use of Aleppo pine tannins in wood adhesive formulation. Thermomechanical analysis (TMA) and strength analysis of Aleppo pine tannin/hexamin based resin showed important bonding properties.